Short Wave - Your Multivitamin Won't Save You

Episode Date: December 19, 2022

Dietary supplements — the vitamins, herbs and botanicals that you'll find in most grocery stores — are everywhere. More than half of U.S. adults over 20 take them, spending almost $50 billion on vitamins and other supplements in 2021. Yet decades of research have produced little evidence that they really work. Aaron Scott talks to Dr. Jenny Jia about the science of dietary supplements: which ones might help, which ones might hurt, and where we could be spending our money instead. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey there, Shortwavers. Aaron Scott here. And if you're anything like me, you might begin your day by chasing down your breakfast with a small alphabet of vitamins and other supplements. More Americans are taking dietary supplements. Americans love their supplements. Soft gels, tablets, liquids. It's a giant industry on the rise.

After all, Americans spent nearly $50 billion. alone on supplements last year. The supplement industry is booming. More than half of U.S. adults over 20 take them. And there are all sorts of claims about how vitamin X will cure Y or mineral Z will prevent any number of bad things from happening to you. But is there anyone who's actually reviewing these claims to see whether these little pills do what they promise?

These supplements are not regulated as... pharmaceutical medications, they're regulated as food. And so I think there's just sort of a lower burden for proving effectiveness. And it makes it sort of easier than to also market them, because they can sometimes make claims that just can't be proven, really. This is Dr. Jenny Jha, a researcher and instructor at Northwestern University's Feinberg School of Medicine. She co-wrote an editorial in the Journal of the American Medical Association called Multivitamins and Supplements, Benign Prevention, or Potential? harmful distraction. It was in response to the newest guidelines issued by the U.S.

Preventive Services Task Force, which is basically a group of doctors and other experts who review the evidence for things like supplements and then make recommendations on preventive care. They state that there's insufficient evidence for use of multivitamins for the prevention of heart disease and cancer in Americans who are healthy. So this is excluding Americans. who are pregnant or intend to become pregnant or Americans who already have known chronic diseases or known vitamin deficiencies. So basically, the task force found that after decades of research, there's just no compelling evidence that multivitamins and other popular single vitamins and minerals, things like vitamin C,

D, E, and calcium, there's no evidence that they actually do anything to prevent things like heart attacks and cancer or otherwise prolong a healthy person's life. So today on the show, we head to the supplement aisle to look at the science and ask if we might all be better off hanging out in the produce department. I'm Aaron Scott, and you're listening to Shortwave, the Daily Science Podcasts from NPR. But we don't take ourselves that seriously here at Shortwave. We take the science super seriously. And that means tackling the occasional science myth. So if you're into tracking down the truth with us, consider signing up for NPR Plus.

You get the show ad-free and you help us get to the bottom of the big questions in science. Join now at plus.mpr.org slash shortwave. And if you're already a subscriber, thank you for your support. To put together its guidelines, the U.S. Preventive Services Task Force looked at 84 different studies, covering nearly a quarter million people. The accompanying editorial by Jenny John and two other researchers at Northwestern sums it up as one of our co-authors puts it this way. The task force isn't saying don't take supplements.

But if they were really helping us, we'd probably know by now. If there is any beneficial effect, it's not really being measured despite large studies. And if there truly is any beneficial effect, it's going to be very small. Like if you're high risk, you multiply your high risk by the tiny benefit that comes from the vitamin. your risk is still pretty high. And so the task force focuses on multivitamins and a couple of kind of single vitamins and mineral supplements and their effects on cardiovascular disease and cancer. Can you explain a little bit more why they focused on the things they did?

The causes of death in this country have gone from, you know, infectious diseases of century ago to chronic diseases, a lot of these, you know, having to do with exposures over one's lifetime, things like what you're eating, how much you're exercising. And so nowadays, heart disease and cancer are two of the most common causes of death of Americans. And so it would be important for the U.S. Preventive Services Task Force to focus on those particular diseases. It's important to say here that people take vitamins and other supplements for all sorts of reasons, everything from better mood to deeper sleep to healthy joints. And this study is not

looking at every single herb and vitamin you're going to find in the supplement aisle. But if you're a generally healthy person who hasn't been diagnosed with any vitamin deficiencies, and you're taking multivitamins or other popular vitamins and minerals just to boost your health with the idea that, you know, they might make you less likely to die of things like cancer and heart disease, well, this study is some pretty clear implications. It seems like these are really a bit of voice. of money right now. Most of them probably don't really hurt, but they also don't really work. And so you may end up wasting your money on them. And especially I think with this review showing that there are actually some harms to vitamins, I think one of the other reasons why they are popular is that there

is a general perception that they're all benign. But that's not actually true in the case of beta carotene. It is linked to lung cancer, especially in Americans with a higher risk of of lung cancer, such as people who are active tobacco smokers. And why is it that supplements don't seem to work as a substitute for the real deal? I mean, what's different about taking a high concentration of vitamin A as a pill as opposed to eating carrots and other foods that contain it? It's really hard to study this, right? Because a carrot is a package of several different substances.

We had an idea of maybe these key elements are what really makes the carrot health. You know, when they're in a package, they're all working together, interacting in a way that we really can't mimic in testing when we actually then extract individual components out of the original whole food. What are the dangers of people relying on supplements? I think that supplements can be distracting. You know, I can understand that, you know, making sure you're getting regular exercise every week, making sure you're eating your fruits and vegetables every day. that does take work. It either takes a lot of money or a lot of work or sometimes both. And it's reasonable to think, well, maybe I could just take a pill. It's not that expensive. It's got all these things that people tell me you're good for my health. But that's just not the way it works,

unfortunately. Thus far, we have not found the silver bullet to being healthy without engaging in healthy practices on a pretty regular basis. This is far from the first big study to look into whether multivitamins and other supplements, actually make us healthier. And the findings have been pretty consistent. They show little, no, or at best, ambiguous benefits. Nonetheless, Jenny says it's still really hard to get that message out. As a clinician, I do have to spend a lot of my time trying to convince people of things

that they may not be convinced of. And I have found the most important thing is to, first of all, ask them why and to really understand what their intentions are. So let's role play here. Like, pretend I'm a patient and I come to you and I say, you know, I'm taking a really high dose of vitamin C because I'm pretty certain that it's going to, you know, boost my immune system and make me live a longer, healthier life. What is your response? I think sometimes in the conversation, if it feels like they're open to it, I will go into, you know, that with vitamin C, particularly if you take high doses of it. There are side effects, too.

There's an higher incidence of kidney stones. but really thinking more about how do I redirect the conversation towards other things and not necessarily just completely shut them down. So at the individual level, making sure that you are eating a balanced diet that's high in fruits and vegetables, usually at least five servings of fruits and vegetables a day. So increasing your whole grain intake, trying to eat proteins that are healthier, things like lean meats or even plant-based proteins. And then a regular physical activity weekly, at least 150 minutes per week, hopefully divided between three to five sessions.

Dr. Jenny Jha, it is been a pleasure to talk with you. Thank you for taking some time with us. Thank you so much for having me. This episode was produced by Margaret Serino and edited by Gabriel Spitzer. Britt Hansen checked the facts and our audio engineer was Stacey Abbott. Giselle Grayson is our senior supervising editor. Brendan Crump is our podcast coordinator. Beth Donovan is the Senior Director of Programming, and Anya Grumman is the Senior Vice President of Programming. I'm Aaron Scott. Thanks for listening to Shortwave from NPR.