Ten Percent Happier with Dan Harris - The Science of Supplements: What Works, What's Hype, and What Could Actually Harm You | Dr. Mahtab Jafari

Episode Date: May 11, 2026

Creatine, melatonin, peptides, protein powders, green powders, probiotics, multivitamins, and much more: A pharmaceutical scientist breaks down the evidence and busts the myths. Dr. Mahtab Jafari is a Professor of Pharmaceutical Sciences and Ecology & Evolutionary Biology at the University of California, Irvine, and the Founding Director of the UC Irvine Center for Healthspan Sciences. She is the author of the award-winning book, The Truth About Dietary Supplements: An Evidence- Based Guide to a Safer Medicine Cabinet.   In this episode we talk about: Product quality, safety, and regulation The most important thing to do before starting dietary supplements Vitamins B, C, and D (and the multivitamin debate) The research on amino acids and peptides The truth behind sleep supplements The efficacy of herbs, botanicals, and green powders Heavy metal risk factors Supplements for brain health and muscle growth Probiotics and gut health Get the 10% with Dan Harris app here Sign up for Dan's free newsletter here Follow Dan on social: Instagram, TikTok Subscribe to our YouTube Channel Join Dan and Emmy Award-winning journalist Allison Gilbert at 92NY on May 17th for a live conversation about how mindfulness can deepen connection and combat loneliness, available in person and via streaming. Register here. Join Dan, Sebene Selassie, and Jeff Warren for Meditation Party, a 3-day immersive retreat at the Omega Institute in Rhinebeck, NY, October 16–18. Grab your in-person spot here, or sign up to livestream here! This episode is sponsored by:  BetterHelp: Find support and have someone with you in therapy. Sign up and get 10% off at BetterHelp.com/happier. Fast Growing Trees: Get 20% off your first purchase when using the code HAPPIER at checkout, fastgrowingtrees.com. Warby Parker: Buy one prescription pair and get 20% off any additional prescription pairs at warbyparker.com/happier.  To advertise on the show, contact [e-mail] or visit https://advertising.libsyn.com/10HappierwithDanHarris

This is the 10% Happier Podcast. I'm Dan Harris. Hello, everybody. Today we're talking about one of the most confusing and controversial areas of wellness and fitness, and that is supplements. Should you be taking them? Which ones should you be taking? How do you know? How do you separate fact from fiction in the midst of this multi-billion dollar, almost entirely unregulated business where people are making all sorts of wild health claims. So what to do about all this? We brought in a ringer, an expert, Dr. Matab Jafari. She's a professor at the University of California, Irvine, and she's also written a book called The Truth About Dietary Supplements, an evidence-based guide to a safer medicine cabinet. Real quick, as many of you know, one of the

major use cases for supplements is, of course, sleep, which is why we are this week over on the 10% app adding a ton of new sleep content. We've just added 10. new sleep meditations. We're also going to be doing a live session tomorrow where our teacher of the month, Kar Lai, is going to talk about how to use meditation for sleep. And alongside all of this, we'll be doing some sleep-centric content here on the pod. The sleep, as you know, is the apex predator of healthy habits. Nothing works without it. By the way, if you sign up for the app, which you can do over at Dan Harris.com, you will also get this podcast without any ads. So head on over to Dan Harris.com. Okay, enough out of me. We're going to get started with Dr. Matab Jafari right after this.

One of the things that happens in spring is you end up in pictures more frequently. If you're going to weddings, which my wife and I, we've got two coming up, or if you're taking trips, or if you're hanging out with your friends on rooftops, a lot more pictures are being taken, and you have to be in them. And if you wear glasses, you want to look good in your frames. You want to love your friends, which brings me to one of our sponsors today. Warby Parker. My wife Bianca has a huge Warby Parker fan. She's got several pairs of Warby Parker glasses, including one she has on her person pretty much all the time, as she would attest. Nothing comes close when it comes to quality price selection and customer service. Once you buy from

Warby Parker, you realize how much easier they've made the entire process. They even have this thing called virtual try-on. You can literally try-on glasses from your phone before you buy them. It's wild how well it actually works. Now is the perfect time to upgrade your glasses for spring by one prescription pair and get 20% off any additional prescription pairs at Warbyparker.com slash happier. That's 20% off additional prescription pairs when you go to W-A-R-B-Y Parker.com slash happier. This episode is sponsored by BetterHelp. May is Mental Health Awareness Month and a reminder that whatever you're dealing with, you do not have to deal with it alone. I actually just came through a little bit of The depressive episode in my life was super difficult, but I got a ton of help from my therapist,

also my family and friends, but my therapist in particular was just super available, really helpful with insights and recommendations and medication tweaks. Really, that's what you need, I think. For me, as somebody who's been in therapy since I was a child, it's just a must have when it comes to personal flourishing. So if you're in the market for a therapist, you might want to check out better health. Help. Better Health therapists work according to a strict code of conduct and they're fully licensed in the U.S. BetterHelp does the initial matching work for you so you can focus on your therapy

goals. A short questionnaire helps you identify your needs and preferences and then their 12 plus years of experience and industry leading match fulfillment rate means they typically get it right the first time. You don't have to be on this journey alone. Find support and have someone with you in therapy. Sign up and get 10% off at betterhelp.com slash happier. That's BetterHELP dot com slash happier. Dr. Matab Jafari, welcome to the show. Thank you and thank you for having me. It's a pleasure.

I'm so eager to talk about this because I have so many questions and I've been so confused about this stuff for a long time. Let me start though by getting some background information on you. How did you get interested in this? My understanding is it has its roots in your childhood and perhaps even with your grandmother. Yes, it does. So I've been doing biomedical research for the past 30 years in various capacities, but mainly in academia. But growing up in Iran, every time I had a minor illness, stomach pain or anything, my grandmother would give me some herbs from her own garden, not from a bottle.

I usually felt better after getting those remedies from her. So that's how it all started because she also had. at a garden and she grew her own herbs and fruits and vegetables. But then when I became a professor and I started my own lab and my research, I delved a little bit obviously deeper into it because I was a skeptic with some of the remedies that my grandmother used to give me. And the more I studied plants and botanicals, the more I realized how powerful they are. But as far as the research and my work on dietary supplement goes, it really started with questions that I get from people. The questions usually start by, you know, my neighbor or my friend recommended this

supplement. What do you think? This has been going on for two or three decades now and I finally decided to write that book to really create awareness and talk to people about the safe use of dietary supplements. So my work predominantly, my research, at the University of California in Irvine, now focuses on safe use of dietary supplements, testing botanical extracts and dietary supplements in my lab, really creating this awareness, again, on the safe use of dietary supplements.

Okay, so I'm going to ask you a bunch of the questions that your friends and family members and neighbors have been asking you for decades. But before I get into that, because I have a million questions about peptides and vitamins and all these other things. Let's just talk about the overall landscape. Eleanor Vassili, who was producing this episode, gave me some research coming into this.

That kind of blew my mind. According to PubMed, the global dietary supplement market is estimated to be valued between $150 billion and $275 billion a year, I believe. Those estimates are a couple of years old, so it may be bigger than that now. What's your sense about the size of this market? And why is it getting bigger and more popular all the time? I think that these numbers are accurate. When I give public talks on dietary supplement,

I usually have a slide that presents data on the market, on the number of dietary supplements. And the estimate for 2025, 2026 used to be like 50 or 60 billion, but it's way more than that. It's very close to the number that you just said. The question is why? because as you mentioned, this is an unregulated market. So the question is why people reach for dietary supplements?

And of course, the answer is multifactorial. I like to say that the social media and the marketing practices play a huge role. People like to have agency when it comes to their healthcare and they feel like by reaching out to dietary supplement, they are taking proactive steps to help themselves. So that's like the psychological aspect of taking supplements. Everybody wants to be healthy. Everybody wants to improve their wellness, their health.

If you don't have training to really understand the science, it's sometimes hard to differentiate science and pseudoscience when it comes to marketing practices. So I wish I had a one-line answer to your question, but it's really multifactorial, of why this industry is exploding. You don't need to have one-line answers for anything here. You can be as nuanced as you want.

I just want to give you permission. So when you say it's unregulated, does that mean that if I, you know, decide to have Dan Harris's protein powder tomorrow, I can make any health claims I want? And also, is anybody going to test my product? Dietary supplements are considered as food now. So if Dan Harris wants to come up with his own, let's say, protein supplements, you can do that. FDA is not going to regulate, when I talk about regulation, meaning that FDA uses different guidelines when it comes to dietary supplements compared to pharmaceuticals.

So a dietary supplement does not need to be approved by FDA before it reaches the market. So you can create your own supplement and you can put it on the market. and FDA requires that you practice good manufacturing practices and also make sure that you don't use ingredients that are dangerous to public. And really, the burden of proof when it comes to the quality of dietary supplement is on people, is on consumers, is on us. FDA gets involved when a dietary supplement has reports of side effects. So you can go on Medwatch.

It's a program that FDA offers, and you can type in a side effect that you're experiencing with a side effect. And then those complaints become, like, let's say when they are at the, I don't know the exact number, so I don't want to say anything wrong. But when those complaints increase on this website, then FDA starts looking into that company in particular to see why this is happening. And as far as the claim goes, FDA requires dietary supplements to have a statement. I'm sure you've seen that.

It says this statement has not been approved by FDA. So you can make any health claim that you want as long as you have that statement. I don't want to say always because you can make outrageous claims. But let's say that you want to say this supplement is going to help you sleep better, is going to improve the quality of your sleep. Then you just have to put that statement that this. statement has not been approved or reviewed by FDA. And that's pretty much it. That's all the regulations we have right now. Okay, Dr. Jafari, please excuse my French. But this system that

you're describing sounds fucking insane. Given the size of this market, given the sheer number of people who are relying on these products, the fact that the level of regulation is so low and in some cases, non-existent, it just seems howlingly irresponsible. It is. I agree with you. It is really an insane situation. As an educator and researcher, what makes it even harder is the public perception. A survey was conducted not too long ago asking Americans, how do you feel about your supplements? Do you think they're safe? Do you think they were FDA approved. And almost half of the people thought that, yes, there is some sort of regulation for these supplements before they hit the market. More than half said that if this

supplement is harmful, it should not be on the shelves of stores. So yes, we definitely have a long way to go when it comes to regulation. And this is what I constantly talk about in my lectures and in my public presentations, that we need to have better regulation for dietary supplements. You said that there's some burden on the supplier not to put harmful ingredients into these powders and potions that they're peddling, but I understand that actually adulteration and contamination are real problems. Yes. So the burden of proof when it comes to the safety, and the quality of supplements is on us. So you and I, as consumers, we have to do our own homework,

and we need to make sure that the supplement that we are taking has good quality. On the manufacturer's side, they have to follow good manufacturing practices. I mean, this is something that FDA requires. But as I said, FD is not going to, for instance, verify the dietary supplement before it hits the market. And you're absolutely right. There has been cases of adulterations, contaminations, and these issues persist, and in my mind, it is going to continue to persist until we have better regulation.

Having said that, the good news is that there are some responsible dietary supplement companies out there who practice transparency when it comes to where they get their ingredients, and there are third-party organizations such as NSF, USP, who come in and test those dietary supplements and give the company a stamp, a USB stamp or an NSF stamp, to say that, yes, we have tested their products and it is safe. But not every dietary supplement company goes through that process because it's extremely expensive, time-consuming, but the minimum is to study the company as a consumer

and see if they are transparent from where they get the raw material and how they are manufacturing that supplement. So I think what you're saying is if I'm tempted to buy a supplement, I'm in a store, I'm looking at a rack of supplements or an influencer I follow is recommending a supplement. I should check the label to see if it's USP or NSF certified. And if it's not, I should think twice. Well, you should think twice, but there are other ways to check for quality. For instance, Consumer Lab, I highly recommend people using Consumer Lab.

It's another third-party organization that look at the quality of supplements. So let's say the supplement that you are taking doesn't have that stamp because many supplements don't. Smaller companies usually cannot afford going through that process. So the minimum is to make sure that when you go on ConsumerLab.com and put in the name of the supplement and company, you're not under what I call troubled problem or red list, meaning that the supplement has had issues with quality. And another way to check the companies to go on FDA.gov and see if FDA has issued any warning letters, any injunction letters,

or any type of warning to that company when it comes to the quality of their supplements. So again, you and I as consumers have to do our home. homework to make sure that the supplement is safe and has good quality. Boy, that doesn't seem like the smart system, but we can stipulate that. All right, so let's get a little bit deeper on the types of supplements there out there. I'm going to list what I think are the various types, but please revise and extend my list if I've screwed up. But I think we're talking about things like vitamins, minerals, herbs and botanicals, proteins, probiotics, and enzymes, and now everybody's talking about peptides.

Is that a reasonably exhaustive list? That's a very good list. So let's go through these. What are, and this is going to be an embarrassingly basic question, so I apologize up front, but what are vitamins? Vitamines are nutrients that we find in various foods, fruits and vegetables and dairy products and meat products that we consume that are essential for our health and homeostasis, meaning that we need to have them to survive and to have a good health.

And some of them serve as co-factors, meaning that they are very, very important when it comes to physiological pathways and what makes us be healthy. And some of them contribute to the health of various organs in our bodies, such as our bones, our muscle, our brain. this is a very broad definition of what a vitamin is. And if we talk about specific examples, I'll be happy to tell me what that vitamin does exactly. Yeah, I do want to get into specific examples, so thank you for the invitation. Let's start with vitamin B. I've been taking it

for years, starting back when I became a vegetarian slash sometimes vegan. I'm not that now, but I still take it. Should I and other people be taking vitamin B? And If so, how do we know whether we should be taking it? So, like with other vitamins, the first question that you have to ask yourself is, do I need them? And how do I need these supplements? And when you say vitamin B, there are different types of vitamin B. But the ones that people usually reach for, I mean, the most commonly used one is B12. So the first thing you have to do is to see if you are B12 deficient.

As you mentioned, unless you are a vegan or a vegetarian, most of us are not B-12 deficient because we get enough vitamin B from meat and from other food products that we consume. But let's say you do a blood test and your vitamin B-12 deficient, then the chances are that you need to take that supplement. And there are also, of course, it's not just the deficiency in your blood with a blood test, but there are some other diseases that require B-12. B12 or B supplementations, and that is different types of anemia's and other diseases. So again, the first question is, do I need to take it?

And in your case, when you were a vegetarian vegan, the chances of needing to take B12 was pretty high. Right. So what you're saying now is that next time I go to the doctor, I should closely examine my blood test results. And if there is no B deficiency, I may want to talk to my doctor about no longer taking this supplement. Yes, absolutely. It's a very simple test. It's not that expensive because sometimes people tell me that, well, I can afford it. And then my immediate answer is that, well, I promise you that the cost of the blood test is cheaper than what you're paying for the supplement on an annual basis.

So it is a very simple blood test, and you can find out if you're B12. deficient or not. And then supplement. If you're deficient, then yes, you should definitely supplement. Just to reset for people, we're working our way through, I'm going to politely, I hope, ask Dr. Jafari to help us walk through various types of supplements and separate fact from fiction. But I do want to digress from that slightly to pursue this question of blood tests. A key question for listeners is, like, how do I know if I need any kind of supplement. So when we go to our doctor, what kind of test should we be asking for generally? We should definitely ask for a comprehensive and a general assessment of vitamins. And it's very easy to test for vitamin D, B12, iron, magnesium and things like that. So that is like the basic. And I think

this is something that should happen every year. So once a year, we should be. check for these vitamins. But sometimes we may need to go one step further because, for instance, you may be supplementing with vitamin D and you're on a high dose of vitamin D and you're still deficient. So this is when you should also consider doing a genetic test to make sure that you don't have a gene variation that can cause vitamin D deficiency even if you're taking high doses of vitamin D. And that genetic test, look at your predisposition or your genetic variance for vitamin D receptor gene.

And that will tell you if you may need higher doses of vitamin D and what the underlying problem is. And I use vitamin D as an example. And there are other genetic tests that can be done for other vitamins. But the basic and to begin with, when it comes to deficiencies and recognizing them is to do a blood test. And should the blood test be looking at just our, whether we have vitamin deficiencies or should it be testing things like our overall nutritional status, liver function, electrolytes, things like that? I'm so glad you brought it up. So I was

referring to just testing for vitamins, but anybody who wants to start taking dietary supplements, they have to have a baseline liver function test, a baseline kidney function test, and also electrolytes, as you mentioned. Many of these supplements use liver for metabolism. So if we have liver dysfunction, they can be very harmful. And kidney function is another one that is very, very important that we have a baseline kidney function,

because again, these supplements use kidneys to either be reabsorbed, excreted, or ending up in our urine. So baseline liver and baseline kidney function tests are very, very important. And especially in older adults, we recently published the paper looking at the case reports and the incidence of side effects and interactions with dietary supplements in older adults. And definitely in older adults, as the age, our kidney function and liver function kind of deteriorates.

I don't want to sound very negative here, but it is part of the aging process. So we definitely need to have a baseline. So just to put a very fine point on this, next time we go to our doctors, if we're interested in supplementation, what exactly should we be asking for in terms of our blood test and how much is this likely to cost us? The good news is that most insurance companies cover this test. So it is part of the annual checkup and we don't have to pay for them. The most basic is to make sure that we have a complete metabolic panel that includes the liver function and kidney function. We want to make sure that we have a complete blood panel, the CBC they call it.

And then part of the annual checkup is always checking for electrolytes, the kidney function, the liver function. It is a very comprehensive blood test that is included when we do the annual check. And as I said, insurance companies pay for it. Are there things we should avoid in terms of testing? I believe you've expressed some skepticism about tests that analyze hair and DNA and things like that. So again, just like dietary supplements, these diagnostic tests or tests to assess for nutritional status are also very popular. When you go on social media and look at marketing practices, these tests are also very popular. I don't want to say all of them, but last time I checked, they were not FDA approved.

So you mentioned hair analysis, so we just published the paper looking at the level of minerals in hair and compare it to blood sample. Because a lot of people think that it's non-invasive, I can just do a hair test, and I can find out what mineral deficiencies I have. So we cannot say that a hair test analysis when it comes to mineral is the same thing as a blood test, because a blood test shows what I'm experiencing right now or over the past week or two weeks or acutely. A hair test is going to show you what your deficiencies and excess are over a long term. Does it have a clinical value?

Yes, because sometimes with some professions you're exposed to heavy metals, and other environmental toxins. So they accumulate in our hair. And the hair test becomes valuable in those situations. But a hair mineral analysis cannot replace a comprehensive blood test. Much more with Dr. Jafari right after this. This episode is sponsored by BetterHelp. May is Mental Health Awareness Month

and a reminder that whatever you're dealing with, you do not have to deal with it alone. I actually just came through a little bit of a depressive episode in my life was super difficult, but I got a ton of help from my therapist, also my family and friends, but my therapist in particular was just super available, really helpful with insights and recommendations and medication tweaks. Really, that's what you need, I think. For me, as somebody who's been in therapy since I was a child, it's just a must have when it comes to personal flourishing. So if you're in the market for a therapist, you might want to check out BetterHelp. Better Health therapists work according to a strict code of conduct and they're fully licensed in the U.S. BetterHelp does the initial matching work for you so you can focus on your therapy goals. A short questionnaire helps you identify your needs and preferences and then their 12 plus years of experience and industry leading match fulfillment rate means they typically get it right the first time. You don't have to be on this journey alone. Find support and have someone with you in therapy. Sign up and get 10% off.

off at betterhelp.com slash happier. That's better help.com slash happier. One of the things that happens in spring is you end up in pictures more frequently. If you're going to weddings, which my wife and I, we've got two coming up, or if you're taking trips, or if you're hanging out with your friends on rooftops, a lot more pictures are being taken and you have to be in them. And if you wear glasses, you want to look good in your frames. You want to love your friends, which brings me to one of our sponsors today, Warby Parker. My wife Bianca is a huge Warby Parker fan. She's got several pairs of Warby Parker glasses, including one she has on her person pretty much all the time, as she would attest. Nothing comes close

when it comes to quality price selection and customer service. Once you buy from Warby Parker, you realize how much easier they've made the entire process. They even have this thing called virtual try-on. You can literally try-on glasses from your phone before you buy them. It's wild how well it actually works. is the perfect time to upgrade your glasses for spring by one prescription pair and get 20% off any additional prescription pairs at Warbyparker.com slash happier. That's 20% off additional prescription pairs when you go to W-A-R-B-Y Parker.com slash happier. Okay, one last question about testing. If we see that we've got some sort of deficiency based on the tests that you recommend, is the move to go to supplementation first or see if we can make up for the deficiency

via our diet? So my first recommendation is diet because if we have a good diet and if our nutrition is balanced, the chances of needing supplements is very, very low. So really the first place to start is to have a very honest evaluation of our nutritional intake to see how our diet is. But sometimes, even with good nutrition, you may need supplementation. And that's when you go to take a dietary supplement. But these conversations should happen with your healthcare providers. So my recommendation to people is that when you go for the annual checkup, when you go to see your physician, take your supplements with you. For instance, if I am checking your nutritional status and I see that you are high in vitamin B12,

I need to know what supplements you are taking and at what doses. That is a recommendation that I always have is to take your supplements to your doctor's appointments, to make sure that you have a conversation with them. and then if you are deficient in something, first place to start its diet. Okay, this is very helpful. Thank you for bearing with me on the digression into testing. Let's go back to marching through the list of various types of supplements to get your take on them. We talked about B, vitamin B, specifically B12, which, as I mentioned, is something that I take. Something else that I take that I think is very common, although I am now questioning whether I need it, is vitamin D.

Many years ago, my doctor pointed out that my vitamin D levels were, in his words, in the toilet. So I just started taking a little vitamin D every day. I've also, though, started to get a little bit more discipline about getting outside. So perhaps I don't need vitamin D, and I don't even sure if the supplementation would help in the first place. So I said a lot there. What's your take on D? Vitamin D is an interesting vitamin, and very interesting and sometimes controversial topic. Based on reports, 40% of adult Americans are vitamin D deficient.

So maybe when you were deficient, you were in that group. So now the question is, how do we define deficiency? And if you go and use pop med or Google vitamin D deficiency, it looks like almost every health association has their own definition of deficiency. The number that I use is 20. So anything less than 20 is considered deficient, and it really requires supplementation. But then the question is where you are and at what stage of your life you are at what age you have and what are some other medical conditions that you have.

So if you have somebody who has osteoprocess and you've had spontaneous bone fractures, the chances are that you probably need to pay attention to you. your bone health. And you may need more vitamin D because we just don't get out as much as we should. You know, we are not exposed to sun. The use of sunscreens and everything else really reduces organic production of vitamin D that we can have naturally. So that's when supplementation is important. And how to supplement really depends on your blood level. If you are less than 20, you may have to start with 2,000 units a day. If you are in the, let's say, 40 to 60,

you may not need supplement, but you still have to check your, you know, vitamin D levels to make sure that they don't fall short. But the recommendation is 1,000 units a day if you are not getting enough some exposure. So I don't know if I answered you a question. Well, I think it comes back to tester levels, talk to your doctor, and if it's indicated, take it.

Absolutely, yes. And we'll probably end up repeating that as I march through this list a lot, but people need to hear it. But let me just ask a few more questions on vitamins. Vitamin C, many people, including my wife, who's a doctor, will recommend taking some vitamin C if you are starting to feel a little sick or you're worried that you've been exposed. What say you? Vitamin C is a very interesting vitamin because we have been studying vitamin C, believe it or not, for almost 80 years. And we have different types of studies, some suggesting that vitamin C is not

going to do anything to your cold virus, decreasing the duration or the symptoms, and some studies suggest that it does. If you look at these studies collectively, I like to say that when you feel like you are about to get sick. Taking vitamin C, not at very high doses, because I've seen people taking three or four grams, which I do not recommend. But taking maybe 500 to 1,000 milligram of vitamin C is going to probably be helpful to decrease the duration of your hold, maybe by 1.5 days. That's what the summary of these studies are.

But it is really not going to help much. And we have wonderful sources of vitamin C in our diet, you know, oranges. Strawberries actually have more vitamin C than oranges and kiwis. If you feel like you're getting cold, and sometimes, I mean, I don't want to be disrespectful to people who believe in vitamin C, but sometimes the placebo effect also works. So if you take vitamin C at lower levels, 500 to 1,000 milligram a day, it wouldn't help. But daily intake of vitamin C is not really recommended. They have done studies in travelers who have taken vitamin C, compared them to travelers who didn't take vitamin C to say which ones get more sick and there was no statistically significant differences.

I don't know if they still sell this, but I remember in the airports they would sell something called Airborne, which was, I think, a multivitamin and you drop it in your drink and it dissolves and it tastes good. I used to take it, but it sounds like it may not be that useful. If you have a good diet, if you have a balanced good diet, the chances of being helpful is not that high. But airborne is still being sold. I don't know the ranking, but it's pretty high on the list of most popular and sold dietary supplements, especially during the flu season and cold season in winter. And airborne is not just vitamin C. It also has some other vitamins.

It has zinc and a few other. So I think what you're saying is it probably won't help as a preventative measure, but what if you're starting to feel the first tingles and aches of a cold will zinc and vitamin C and maybe echinacea? Will any of that help? You mean, you mentioned C might help a little bit, but what about those other supplements? There have also been studies published on these other supplements, and in my mind, the jury is still out. and there is a very minor, I would say minor significance and minor trend towards these supplements helping to reduce the symptoms and maybe to reduce the viral load. But as I said, there are no good randomized clinical trials looking at them.

And of course, the issue of clinical studies on dietary supplements is something that we can probably spend a few hours on. Okay, one last vitamin question. I think a lot of people just reflexively and habitually take a multivitamin. I suspect your answer is just going to be able to run the test, talk to your doctor, but I just want to check if there's anything more to say. Multivitamins, as you mentioned, commonly used, I think last time I checked the statistics, almost 30% of U.S. adults take a dietary supplement, and I think the number is probably higher than that.

So with multivitamins, again, I want to go back to the basics. The first question is, do I need them? If I have a very good diet, the chances of needing it is pretty much zero, because the amount of various vitamins that we get in a multivitamins are pretty low. So let's say you are D deficient, 40 units or 50 units of, or even 100 units of vitamin D in a multivitamin is really not going to be helpful. You have to supplement. So the amount of these vitamins in a multivitamin is important. But going back to studies, study after study shows that multivitamines are not going to improve our health.

Two recent studies actually show that taking multivitamins increases mortality. So patients who have been taking these supplements, they had a higher risk for mortality. But I want to step back because this can become like a headline news that, oh, taking multivitamins, it's going to increase your mortality. But if you look at the populations who were enrolled in these studies, you have to ask yourself some very basic questions. So maybe people who are taking multivitamins are sicker in general. Their baseline health is not optimized. And this is why they are taking vitamins. And this is a problem that we have with both dietary supplement studies is the study design and looking at the characteristics of the populations,

that they recruited and were included in these studies. For most dietary supplement studies, for instance, we don't have baseline vitamin levels. This has been a big critique of vitamin D studies, especially the ones that fail, because the supporters of vitamin D supplementations would say that, wait a minute, you didn't check vitamin D levels

and you put these people on 400 or 1,000 units of vitamin D, and you didn't see any efficacy, let's say, bone fracture, cardiovascular health, immune health, so you can really make those conclusions. And this is really an ongoing debate when it comes to studies on dietary supplements. But going back to your multivitamin question, if you don't have a sound nutrition, if your diet is not good,

you may consider taking a multivitamine. But then you need to have a conversation with your physician, because you have to look at multivitamins and see how much of each vitamin you have in that supplement. And if you need more. This is just fascinating and sobering. All right, so we talked about vitamins. What are minerals? I honestly don't know.

What is the difference between a vitamin and a mineral? So I give you some examples to just make it easier. So for instance, calcium is a mineral. magnesium is a mineral, and zinc is a mineral, copper is a mineral. So when you test, when you do a blood test, you can also check the levels of minerals in your blood. A very controversial topic when it comes to mineral is the use of calcium, for instance. So we all need calcium in our diet. And I know there are ranges based on the fact if you're a woman or if you're a female or a male,

I usually recommend to people try to have at least 1,500 milligrams of calcium intake every day. So a lot of people reach for the supplements. A lot of people take calcium supplements because they think that the more is better when it comes to calcium. And that is absolutely not true. Going back to the baseline test that we talked about, for instance, somebody who has kidney problems, taking more calcium is really not going to be helpful, is actually going to harm it. them is going to cause more kidney problems, and it is also going to deposit more calcium in our blood vessels, and that is going to be a separate issue because we are going to increase

the risk of developing coronary artery disease. So calcium is great. My recommendation is try to get as much calcium as we can from our diet, but if we still need to supplement, we have to be very careful. Let me ask about another mineral. You mentioned it, magnesium, it's often recommended as a way to help us sleep. What's the truth about magnesium? Does it actually help us sleep? Magnesium is another interesting mineral. Data suggests that 50% of adult Americans are magnesium deficient. You may think that we came up with that statistics because we measured blood magnesium levels, just like I mentioned vitamin D levels, we measured magnesium levels in our blood and be very deficient.

And that's really not the case. The magnesium that we get in our blood test only represent 1% of the total magnesium in our body. 60% of the magnesium in our bodies are in our bones. We are not going to get the amount that we have in our bones in the blood test. So that 50% is based on intake because we have done epidemiological studies and we have observed that most of us do not have enough magnesium intake. And based on that, the intake inadequacy, we decided that, okay, we are magnesium deficient. So now going back to the uses of magnesium, there are some studies, for instance, suggesting

in certain types of migraine, people who have migraine headaches, taking magnesium help them. When it comes to sleep, studies have not been conclusive. Some studies suggest that it may help and some studies suggest that it may not help. I would say that this recent study that was published actually in 2025 look at is probably the best magnesium study. And I tell you why, although the sample size was quite small, I think they only look at 60 adults. The good thing about this study was that the supplement that they used was standardized. It was a form of magnesium formulation, magnesium tyroneate, which crosses the blood-brain barrier, and then it can end up in our brain. And in that study, they showed that magnesium actually improved sleep quality.

And the reason that I liked this study is that it wasn't just based on a questionnaire because I can be very subjective and ask you, Dan, how did you sleep last night? And you said, oh, it was pretty good. So that's very subjective. But in this study, they also evaluated the sleep quality with an aura rate. So what they did was that these people, they were collecting data on their sleep. the subjects in this study in a subjective and objective manner. And they showed that magnesium supplementation helped them improve the quality of their sleep. But this is a small study,

very small duration. I believe the study was done over 21 days. What does that mean long term? We don't know. What I recommend to people when they complain about insomnia and sleep disorders is they again go back to their physicians and have a very open and honest conversations with them. Because often, insomnia and sleep disorders could be because of some other illnesses and some other issues. So just reaching out for a supplement or even a medication to take care of our sleep is probably not recommended. And then it comes to insomnia, of course, you're talking about dietary supplements, but the science shows that cognitive behavioral therapy is probably the most robust intervention to improve our sleep. And meditation. And meditation. Yes. We've had sleep experts on the show before,

and it's been asserted quite powerfully and repeatedly that CBTI cognitive behavioral therapy for insomnia is the biggest winner in this category. I will say, and some of my listeners know this, I'm happy to say I had insomnia for a decade, and it turned out I had something called Restless Leg Syndrome that actually has been effectively treated with a combination of iron supplementation and a few medications. Yes. I'm so glad you shared that example, because if you probably saw a physician to get the diagnosis of Restless Leg Syndrome, if you had not done that, you would be over-medicating and oversupplementing for your insomnia, and it was not good. It was actually harmful.

So now you have a diagnosis and you are tweeting the issue. When it comes to sleep, melatonin, is there evidence that it can help? Yes, melatonin is a hormone that we all produce naturally. We all produce melatonin. Some of us secret less melatonin, so we may need to soft. supplement, even just to improve our circadian rhythm on a day-to-day basis. But for the most part, we have a good production. Most people have a good amount of melatonin. So melatonin could be useful for occasional insomnia. For instance, your jet lag or you're traveling, one to three milligrams of melatonin is not going to be dangerous. A recent study really raised the alarm on the use of melatonin.

it was actually published four or five months ago, and they look at 130,000 people who were taking melatonin at least for one year, and they reported that melatonin increased the risk for heart failure in those people. And I don't want to go through the details unless you want me to, but really the premise was that it was changing their blood pressure and heart rate, and this is how these people ended up having higher risk of heart failure. This study was not published. It was an abstract that was presented at the American Heart Association Conference in November of 2025. And it hasn't been peer reviewed.

So when people ask me questions about this study, I say that the study was presented at a conference, at a scientific conference. But to my knowledge, because I checked this last week, it hasn't been published yet. And when it's published, I'm sure that in the discussion or the critique section, we are going to find out what are some of the controversial issues that we have to consider about this study. Having said that, my general recommendation is not to take melatonin on a daily basis. If you feel like you have to take it to fall asleep, then on a daily basis, then again, you need to have a conversation with your physician. One problem with melatonin is also the quality of the supplements. Melatonin can be sedative.

Dr. Cohen at Harvard published this study looking at melatonin gommies, and he reported that some of these gums had 300% more melatonin than what they reported. That means that you can be really sedated in the morning, meaning that you shouldn't be driving and you should really worry. So melatonin can help people to fall asleep, but it's really not a sleep medication. It doesn't help you to stay sleep. Much more with Dr. Jafari right after this.

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That's 20% off additional prescription pairs when you go to W-A-R-B-Y Parker.com slash happier. This episode is sponsored by BetterHelp. May is Mental Health Awareness Month and a reminder that whatever you're dealing with, you do not have to deal with it alone. I actually just came through a little bit of a depressive episode in my life was super difficult, but I got a ton of help from my therapist, also my family and friends, but my therapist in particular was just super available, really helpful with insights and recommendations and medication tweaks.

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You don't have to be on this journey alone. Find support and have someone with you in therapy. Sign up and get 10% off at BetterHelp.com slash happier. That's betterhelp.com slash happier. What category do omega-3 fatty acids fall into? Omega-3 fatty acids are a form of dietary supplements. So they are not vitamins, they are not minerals. As you said, they are fatty acids. And we have to get them from our diet.

Omega-trees and omega-6 is not something that we can just walk around and produce. So we need to get them from our diet. And the good news is that there are different sources of omega trees in our diet. This is another dietary supplement that there is an objective test to evaluate whether we are deficient or we have sufficient amount in our bodies. And that is the omega index. That's again another, actually you don't even need a blood test. It is a finger stick test that you can measure your omega. three levels and the ratio of omega-3 to omega-6 in your blood. And if your omega-3 index is less than 8%, most likely you need to supplement. My psychiatrist recommended a large dose of omega-3s as a

way to elevate my mood, because I've been dealing with a bit of a recurrence of depression over the last couple of months. Any evidence for that recommendation? So when we look at all the scientific studies that have been published on omega-3s, and this is another, I want to go back to the quality of clinical studies, because once again, we sometimes don't know what the baseline of the participants are. They could be deficient in omega-3 or replete, and we wouldn't know because we never check for that index. But if you look at the scientific studies on omega-trees collectively, there are some small studies that suggest that omega-trees are useful for brain health, especially if you don't have enough in your diet. But the studies are not conclusive.

What we know about omega-trees for sure is that if you have high levels of triglycerides and you take omega-trees and sometimes a prescription form, not even, even the dietary supplements, unless again you look for a high-quality supplement, it can decrease triglycerides. So that's why omega-3s are very helpful for heart disease. Omega-trees also have anti-inflammatory properties. Some data suggests that maybe this is why they are also useful for our brain health and cardiovascular function because they decrease inflammation. I think we're now back at our theme.

some arguments for omega-3, but get tested, see what your levels are, talk to your doctor. Yes. I'm not sure we fully close the loop on whether they can help with depression. Did you answer that part? What I shared was that there are studies, there are small studies, suggesting that omega-3s can help with depression, and they can help with brain health in general. some studies even suggest that they can delay dementia. But my conclusion was that these studies were not done long term.

Because, for instance, with dementia, you can test omega-trees in four to six weeks or even three months and say that, okay, they had an impact on the symptoms of dementia. The study has to be long-term. It has to go over years and maybe sometimes a decade. But what I was saying is that the data and the real, results are not conclusive when it comes to the impact of omega-trees on depression, for instance. But again, my own little editorial point here is that if you did take the omega-trees and you feel improvement, then that means that it is working for you. So I am not going to say,

Dan, stop taking it because it doesn't work. And sometimes when I share this answer with the patients that I see or my friends, they say, wait a minute, this is a very wishy-washy answer. You are telling me to take it, but then the data doesn't show that. I said, this is when the personalization come into FF, because if a study shows that, for instance, vitamin D is not going to help with your fractures or decrease the risk of having fractures, and I didn't check the baseline level, but it's working for you, then it's working for you. I don't find that wishy-washy. I find that elasticity to be just wise. And you know, then something else that I like to add is that science is constantly evolving.

So we may have had studies that were published 10, 20 years ago, and the conclusion of those studies are not really consistent with what we are studying now. So we have to remember that when we talk about scientific evidence, scientific evidence evolves, and you're doing a better job with the quality of the studies on dietary supplements. So hopefully we will reach a point that I will have this interview, this dialogue with you and say, the studies are great, the quality of the studies are great, but we are not there yet. On the subject of depression, another supplement that was actually recommended to me by the same psychiatrist, I have not taken this, is St. John's Wart.

What's your take on St. John's Wart? It comes from a plant, so it's a botanical extract. One of the ingredients that this botanical has, one of the hundreds of molecules that this botanical has, is very similar. The chemical structure of that molecule is very similar to SSRIs, selective serotoninary optic inhibitors. So St. John Wurst does have antidepressant properties. But again, it has to be used under the supervision of a physician because St. John's word uses this same liver metabolic pathways that some other drugs use and it may interact with them. So you really need to be under the supervision of a physician. I do not recommend people just going to a store and buying St. John works to improve their mood

and improve their depression because with the understanding that, oh, this is just safe, this is a dietary supplement, this is a natural product, and it's safe. There is nothing safe there because it can interact with your other drugs and supplements. So you mentioned that St. John's Wart is a botanical, and that actually is one of the categories I wanted to ask you about herbs and botanicals. And you mentioned early on in this conversation that your grandmother used to give view herbs and botanical remedies for various ailments when you were growing up. What is your current view on the efficacy of herbs and botanicals now? Humans have used herbal remedies and botanicals for thousands of years. In the context of traditional medical practices, when they use

correctly and appropriately, we know that they work. Going back to my grandmother, for instance, we had stomach pain, she would give us mint. She would grind up some meat, put them in hot water and give us like a mint tea. Of course, she didn't know that by putting the mint in hot water, she's extracting it because you're extracting chemicals out of the mint plant when you do that. And it helped us. Another example that I used from my grandmother is in harsh, cold winters of Tehran. She used to give us like one teaspoon of cinnamon to keep us warm. I really hated that because it was very better. Years later, it was about 10 years ago that we did a study in my lab with cinnamon, and we found out that cinnamon actually activates heat shock proteins. So what I thought it was voodoo by my grandmother is actually, I was able to prove it in my lab, which was very interesting.

So going back to herbs, they can be effective if they are used in the right context. Again, I want to go back. back to the quality of the dietary supplements, especially herbal products, because unless we know the source, we know the farm that they come from, we know the quality of the product, it is really hard to make any assessment about their safety. And one thing that I always talk about is staying away from these blends, proprietary blends, because you may buy an herbal remedy and they list, I don't know, sometimes 10 or 20 different herbs. And there is no information on the dose. There is no information or where these herbs come from,

where they cultivated from an organic farm, responsible agriculture practices. We don't know. I really want people to think twice when they take an herbal remedy that has many different ingredients. Okay, well, that brings to mind AG1, which is an incredibly popular supplement. It's advertised all over.

social media, they've talked to me and my team about advertising on this show. We had a bunch of requests that I don't think went down well with them, and so they're not currently advertisers here. But so what's your take on AG1? My take on AG1 is pretty much what I just shared with you about other dietary supplements. I have not had a deep dive into this particular supplement, so I can't really share any scientific data. I don't know if they are out there. But my take is going back to the quality and making sure that the quality of the product is verified

and it is trustworthy. And if you tell me some of the indications that people are recommending AG1, I can make comments on those two. But I think the basic pitch is that it's just a ton of, it's like having a huge salad. And I don't know if that's a reasonable claim to make, but I think that's the pitch.

This is a very interesting pitch that many companies where they sell these green powders. I think the big umbrella for these kinds of supplements is that use these green powders because we have poor diets, we don't have enough fruits and vegetables, and the green powder or AG1 can replace that. If you're not eating a salad, at least do that.

My take on that is the same take that I have with everything else. Number one, these are highly processed. In order to get to the product, you have to go through some chemical processing. Even if you're freeze-drying, the herbs or the greens, that is considered processing. So they're highly processed. And then the other question is the other ingredients in these green powders, because they don't taste good. unless you add sugar and other additives, it's not really pleasant to eat them. So I want to go back to the question of quality.

And finally, do you think that we are going to get the benefits of the polyphenols that we get from, let's say, a salad compared to AG1? There's really no comparison because a fresh salad that you make at home and you eat has polyphenols and antioxidants that are not processed, they come in your salad bowl and in your salad that you can compare. You can compare the efficacy and the health benefits of whole foods compared to something that is processed. What about protein powders? So protein powders is another interesting topic. And I think we are becoming very obsessed with protein

powders because we are realizing that we don't have enough protein intake. The average adult in U.S. does not have enough protein intake. So now the question is, how am I going to supplement that? For me, the safest and easiest way is with food. So make sure that you have 30 to 40 grams of protein intake with each meal. And I know there are various numbers out there, 1.6 to 2.2 grams per kilogram per day. But my recommendation, I try to simplify my recommendation. So I tell people that you're eating breakfast, look at your breakfast and see if there is any protein there. Look at your lunch, look at your dinner, your snacks. So try to consume enough protein with each meal and if you can with your snacks. Now going back to the protein powders, there have been studied and we know

that some of them have heavy metals, some of them are contaminated. So then again, the question is, how can I assure the quality of that protein powder? A very recent study, I'm trying to remember the funding agency, it was part of the Clean Label Project. And they looked at, I believe, 134 different protein powders out there. And they reported that 47% of them had heavy metals. So now that the question about these heavy metals is that how much of heavy metals? Because if you look at Prop 65 in California, they almost recommend nothing. And that was a big, big critique of that work, is that it was over-exaggerated the amount of heavy metals in these protein powder. But to me, if I am a consumer and I'm looking at the protein powder and there's a 47% chance that this

protein powder may have heavy metal, I would think twice. So I would again go back to my recommendation with protein powders. It is much safer to buy something that has the NSF stamp because NSF regulates sports and nutritional and dietary supplements that are using sports and protein powder, as you know, are heavily consumed among athletes. So I know that I'm starting to sound like a broken tape recorded, but go back to food. Consume your protein from whole foods and in your diet. And yes, every now and then we may need a protein shape, so I don't have anything against that. My sons consume them, but go for a good quality wine. Speaking of athletes, and I consider myself to be, you know, an amateur athlete and, you know,

a dedicated worker outer. I lift weights, et cetera, et cetera. Something I hear a lot, about in fitness circles but have never tried myself and I don't actually even know really what it is so maybe you can educate me. Creatine. What's your take on creatine? Creatine is an emerging dietary supplement. A lot of people confuse it with a type of protein. They said, oh, right after workout, I have to take my creatine because this is going to be another protein I'm taking. It is not. Creating is a dietary supplement. And again, here going back to the science, we've had really interesting studies on creating. So if you are going to the gym and you're lifting and you want to improve the quality and the quantity of your muscle, taking creating can be helpful.

So the recommendation is, you know, after your workout, try to take three to five grams of creating. And if you have a good kidney function, it is pretty safe. Now we have studies suggesting that creating could also be good for cognition. It could be good for brain health. And there is a positive trend in these studies, but I think we need more. The best benefit with creating when it comes to the impact on brain health was observed in postmenopausal women. But if you are an athlete and you're working out, taking creating can be useful. Because I don't know how deep you want me to go into the mechanism of action of creating, but it really helps the production of ATP in our muscle cells, and it also helps with the retention of water. So you may hear people saying that I started taking

creating and I gain weight. Well, the first one to two extra kilogram or four, five pounds of extra weight is because of the water retention in your muscles. This is not really a weight, Unless you're also eating a lot of candies and sugary stuff when you exercise. And the last thing I want to say about creating, because I just got this question actually yesterday, so it's really fresh on my mind, that the type is important. So creating monohydrate is probably the one that you should consume because it's better absorbed. Another supplement that people are talking about a lot these days. I think this is a category of supplements, I think, peptide.

I'm hearing a ton about peptides are all over the internet. What are peptides and what your take on them? If you have a good diet and you consume enough proteins, you probably don't need any extra amino acids and any extra peptides. There are a lot of claims suggesting that when you take peptides, you're going to have better elasticity in your skin, your hair, your nails. And I put peptides in the same category as I put color. that these studies have been very subjective. I mean, not very subjective, but semi-subjective,

because they use surveys and they look at your superficial skin, for instance, to say that if they work and if they don't work. And again, going back to the quality, if you are convinced that this peptide supplement is going to help you, at least go for the right quality. Make sure that the quality of the supplement is good. But the data is not very convincing. Okay, last thing to ask you about, although there are a million other things I could ask you about, but we don't have infinite time. Probiotics, live microorganisms that allegedly aid digestion, so probiotics and enzymes. Any evidence for these? So probiotics are also very popular, and some people just take them on a daily basis.

My recommendations on probiotics is that you have to work on your diet. If we want to have a good microbiota in our gut, probiotics are just going to offer a very temporary solution to a gut microbiota that needs to become healthy with our diet. So my recommendation is if you want to have a healthy gut microbiota, stay away from sugar, especially processed sugar or anything that. has high amounts of sugar and consumed fruits and vegetables. That is how you have a healthy microbiota. Taking probiotics for very specific conditions could be helpful. For instance, if you are taking

antibiotics, I highly recommend that you take a high-quality probiotics while you are taking that antibiotics. And I recommend that you start taking it on day one. And why do I recommend that because probiotics are going to offset the gastrointestinal side effects that, for instance, the antibiotic is going to cause. But taking probiotics on a daily basis, it's really not recommended. There are some specific diseases like ulcerative colitis and Crohn's disease that may require taking probiotics, but again, that's a conversation you need to have with your physician to make sure that you are taking the right one. Because for people, for instance, for immunocompromise for various reasons because they are taking drugs to prevent organ

rejection and things like that, probiotics can actually be quite harmful. Again, you have to look at the quality. They can cause infections. So I highly, highly recommend, again, the conversation with the healthcare providers to choose the right type of probiotics and the specific disease that you are taking probiotics for. You have been very patient with my pesky questions. I really appreciate it. And I want to recommend that everybody check out Dr. Jafari's book. Again, it's called The Truth About Dietary Supplements and Evidence-Based Guide to a

Safer Medicine Cabinet. I will put a link in the show notes if you want to go buy it, which, again, I think would be a wise move if this is a subject you're interested in. But in closing, let me just say, Dr. Matab Jafari, thank you so much. for taking so much time with me slash us. Oh, thank you. Thank you for having me. And thank you for the great questions.

Thanks again to Dr. Jafari. Super interesting to talk to her. I've actually made some pretty significant changes since this conversation. Don't forget, it's sleep week over at the 10% Happier app. You can sign up at danharis.com. You'll get our truckload of new sleep meditations that we're adding this week.

And if you sign up today, Tomorrow, on Tuesday, we're going to do a live session with Carl Lai on how to boost your sleep with meditation. Finally, thank you to everybody who worked so hard to make this show. Our producers are Tara Anderson and Eleanor Vassili. Our recording and engineering is handled by the great folks over at Pod People. Lauren Smith is our managing producer. Marissa Schneiderman is our senior producer. DJ Kashmir is our executive producer.

And Nick Thorburn of the band Islands wrote our theme.