ZOE Science & Nutrition - Most replayed moment: What The Science Says About Supplements | Prof Tim Spector & Prof Sarah Berry

Episode Date: June 23, 2026

Today, we’re talking about supplements. We’ve all seen them; the multivitamins, the fortified foods, the neatly packaged powders promising improved energy, immunity and longevity.  Supplements boast bold claims, however, it’s hard to know if they’re genuinely helpful or just well-marketed. Professor Tim Spector and Professor Sarah Berry join me to unpack why supplements exist, what the science really says about their benefits and risks, and how to decide if supplements deserve a place in your daily routine. 🌱 Try our science-backed and tasty wholefood supplement Daily 30+ Get our brand-new app and Gut Health Test designed by world-leading gut health and nutrition scientists to build healthy eating habits 👉 Join ZOE Follow ZOE on Instagram. 📚Books by our ZOE Scientists The Food For Life Cookbook Every Body Should Know This by Dr Federica Amati Food For Life by Prof. Tim Spector Ferment by Prof. Tim Spector Free resources from ZOE Eating for Better Brain Health: Your brain-gut blueprint How to eat in 2026 - Discover ZOE’s 8 nutrition principles for long-term health Live Healthier: Top 10 Tips From ZOE Science & Nutrition Gut Guide - For a Healthier Microbiome in Weeks  Better Breakfast Guide Have feedback or a topic you'd like us to cover? Let us know hereListen to the full episode here

Hello and welcome to Zoe Recap, where each week we find the best bits from one of our podcast episodes to help you improve your health. Today we're talking about supplements. We've all seen them, the multivitamins, the fortified foods, the neatly packaged powders promising improved energy, immunity and longevity. Supplements boast bold claims. However, it's hard to know if they're genuinely helpful or just well marketed. Professor Tim Spector and Professor Sarah Berry, join me to unpack why supplements exist, what the science really says about their benefits and risks, and how to decide if supplements deserve a place in your daily routine. What exactly are supplements and why were they created in the first place? There isn't an official definition of supplement as far as I'm aware,

but it's usually some chemical that you have as a pill or a liquid or a powder that, will replace a deficiency and improve your health. And this is why we have supplements added to foods all the time routinely. Some of them by law, for example, in breads, when you strip out the normal bit of the wheat, you lose the normal vitamins that are there, the B vitamins. And so by law, you have to supplement that food again with what you're lacking. So that's the general remit, but it's a very broad area. and it's usually taken to be things that are in some chemical form rather than in a food form.

And traditionally when we think about supplements, we think about vitamins and minerals. These are essential for our health. And at a time where there was deficiency, supplements were of value. But we're talking hundreds of years ago, for example, where there was deficiency in vitamin C amongst sailors, which we often talk about in nutrition, that led to something called scurvy. It's almost eradicated now. As long as you're consuming a reasonably balanced diet, it's very difficult to be deficient in these essential vitamins and essential minerals. There are some people at certain stages in their life that may benefit from supplements.

So, for example, iron deficiency inemia is quite a big problem amongst certain populations, but for the majority of people, we get the vitamins and minerals that we need from our diet. And 100 years ago was this very different? Because you mentioned scurvy, and I do remember this in history, you know, like sailors needing to eat lemons or something. It's not only scurvy that you're talking about in these deficiencies. Yep. So there were lots of different deficiencies. It depended on where you were living as well.

And there still are some vitamin mineral deficiencies in other countries who are typically malnourished. but in well-nourished countries like the UK, like the US, it's really unusual. But yes, there were deficiencies years ago, not just in vitamin C, but in many other vitamins and minerals as well. Ricketts, for example, all these pictures 100 years ago in Glasgow of kids with bendy joints, this was a vitamin deficiency that now really no longer exists. We often talk about how the diets in the past were much healthier. So why was it that this concern and actually this occurrence of deficiency?

It generally happened during industrialisation. And the UK was at the forefront of the Industrial Revolution. And people rapidly moved from the countryside where they didn't really have these deficiencies to big cities. And the food supply had to be reorganized. And people ended up just, for example, eating bread or just porridge, didn't get any fresh fruits, vegetables. any variety. And so as soon as you lose that variety, you go onto these staples, you do risk having some of these vitamin deficiencies. So that was the cause of this. And this actually, you see in times of war and displacement of people, that's when you get these vitamin deficiencies

in things like thiamine deficiency, vitamin D, vitamin C. All these occur in major catastrophes. So that's why nutrition was actually set up as a science, really because of the two world wars, dealing with nutritional deficiencies at a population level. So that's why we've been obsessed with this idea that supplements are replacing these nutrients that, for these geopolitical reasons, have been a problem. And this legacy has carried on into the modern day, and we've still got this mindset that we're living in this post-war environment. which no longer is applicable for the vast majority of people.

And I think when we think about supplements, it's thinking about deficiency, which very, very few of us are deficient in most of our essential nutrients, micronutrients. We also think about insufficiency. So if we think about iron, for example, some people who aren't getting enough iron or aren't absorbing it well might have iron deficiency anemia.

There is a place then to supplement with iron. Then there's other people that might have moderately, okay iron stores, but might be quite fatigued and may benefit from some additional iron. So that's in a phase of insufficiency. But this whole idea of adding extra nutrients or adding extra chemicals, vitamins, minerals in to then boost your health, I think that's where we start to go into problems. So using iron again, as an example, if you have sufficient iron stores, this idea that, oh, well, hold on, iron prevents us from feeling fatigued if you have anemia. Let's add more iron in to feel really, you know, this great boost of energy.

If you've got enough, you don't need to add more, and it's not going to make you feel more energetic. And if anything, it can actually be harmful. So it's my analogy a bit like my car needs petrol and it needs oil to function. But as long as it's got enough petrol, enough gas and enough oil, like if I put twice as much oil, actually all I do is like poor oil at the car. I'm not making things any better. Yeah, and I think as well,

bodies are so, so clever. Our bodies know how much we need of these different vitamins and minerals and other nutrients. So for example, with iron, we control the levels within really tight upper and lower boundaries. And we have clever mechanisms to make sure we can control our iron stores, our vitamin stores, our minerals, etc. And by adding loads more in, we're making our body work harder and sometimes they can therefore even be toxic. Because if we don't need it, in many instances, we need to get rid of it to prevent toxicity, and that can put extra strain on our kidneys, other organs, etc. Calcium is another great example.

For the last 30 years, we've been told that we're all lacking calcium, and that's why we're getting brittle bones and fractures are going up. And it was never actually true, and our body is brilliant at keeping our calcium levels exactly right. And when they've done studies, finally showing that when you give people calcium supplements, as opposed to in food. You don't get any benefit on the bones because it doesn't get into them as it does when you're normally eating food. And it can build up to dangerous levels and increase your

risk of heart disease. So again, we've been misled from this old idea that vitamins and minerals were deficient in everybody. Even if you're not deficient, having extra is going to give you benefits, as Sarah is saying, it's across the board. This is this real misconception about this whole field. You're saying they've now done studies on taking calcium as a pill and it actually increases your risk of heart disease? Yes. So it doesn't help fractures, which is what it was supposed to be. It's what I used to prescribe it all the time, giving calcium to menopause or women, for example. It doesn't prevent fractures and there is increasing evidence that it's associated with heart disease, hasn't been proven causally, but it's associated with increased risks of

heart disease, possibly because it's increasing the hardness and thickness of your arteries. So these are just several examples, you know, whether it's vitamin C or it's calcium of this mindset that our body just needs minute amounts of these things, finely tuned, and there's no reason to have 10, 100 times more of it. There's never been shown that that is beneficial. I think, Jonathan, it's always important caveat. And you know, I'm always here to add that extra nuance that I think, yes, in general, adding in these supplements, particularly high doses, is not necessary for the majority of the population who are having a healthy balanced diet. There are certain groups in the population that will benefit. So particularly certain elderly

groups who aren't consuming enough energy, who aren't consuming the right diversity of foods, who aren't consuming enough foods, they may benefit from having just a kind of broad spectrum, multivitamin and mineral. Folic acid, absolutely for women of childbearing age who are trying to get pregnant in the early stage of pregnancy, supplementing with folic acid reduces the risk of neural tube defects between 30 to 75% in different populations. People who have iron deficiency anemia, yes, supplementing with iron in the right way. B12 works very well for vegans who struggle to get their B12 levels up.

We talk about generalities here. There are obviously subgroups that do still benefit from it. So if I understand this rightly, you're saying there are particular groups for whom supplementation makes good sense. Absolutely. As a great example that you really believe in, if you're elderly and you're no longer probably really eating as much food as you should. Or you've got an eating disorder, for example, be another one.

So in those particular cases, but in general, we're not in the world that these vitamins were invented for, which is just industrialisation. you're just basically getting plain white bread every day for months on end when you could actually be missing them. Even with the rather sad state of the diets that we eat today in the West, actually vitamin deficiency is not a problem for most people. Yes. For most people, the thing that annoys me the most when I think, particularly about the neutrophobolics out there, is that you go into some of these supplement aisles and you see these bottle supplements that are promising the world, that you'll look 20 years younger,

that these hair supplements, these menopause supplements, and they're just washed with all of these claims. And, you know, everyone wants a quick fix. Everyone wants a silver bullet. They're not the silver bullet. And often they're marketed at 10, 20 times the price of a standard multivitamin and mineral just because it says whatever claim actually, you know, praise to someone's insecurity or concern that they might have.

People think if I'm paying a lot of money for a vitamin or a mineral supplement, it's got to be good quality. Well, that's not the case. Most surveys show that sometimes they don't even contain the chemical they say they do. Most of them are now made in China. It's the biggest producer of these in vast factories. And I think the majority are now made from genetic engineering of microbes. They ferment them in these big tanks. So people's view of what these are is very different to the reality. And they don't know that when they're taking these, it actually contains the products they think it does or that, you know, they aren't going to have other additives in there that might make sure they don't work or get absorbed. Now, Tim, what I see around me with supplements

is not things that talk about solving my deficiency or the deficiency that, you know, my daughter might have, but making all sorts of health claims, right? So they say it's going to boost my immune system or my brain health or it's like good for my, you know, my children's health. I see that on all the cereal packets. What's going on there? This is a throwback to the post-war years, where they did studies of people who'd suffered famines or had major deficiencies, and the early nutritionists would discover that someone, for example, had hardly any zinc in their diet, were getting lots of infections. So they had zero zinc, the blood levels was zero, and these groups were getting recurrent infections.

If they were placed with zinc, then they got better. That's been translated 50 years on to say that if you add zinc to anybody at whatever level, it's going to boost their immune system or aid their immune system. And is that true? It's rubbish. There's no evidence that additional zinc has any enhancing effects on your immune system once you've relieved the deficiency, and zinc deficiency is incredibly rare if you're not in one of these extreme situations.

So that allows any food manufacturer to add a little tiny amount of zinc to any food, and they can then claim it boosts immune function. It makes me feel very angry because people are being misled, and this allows big food manufacturers to stick labels on foods that are blatantly unhealthy, contain 30% sugar with a healthy label saying enhance or boosts your immune system when the science really doesn't back it up. And we are prevented in many other areas from giving real advice of things that can actually be beneficial for your system. So big food has made sure that these really old-fashioned, out-of-date science stays there and that they can just by adding tiny,

amounts of whether it's copper, manganese, zinc, niacin, whatever, made artificially to bad foods can now give it a health claim. It's ridiculous. It should be stopped. Hosting this podcast means I get to quiz world leading scientists every week about how to improve my health. But I'll be honest with you, for a long time my snacking habit was completely out of sync with the science. I'd hit an energy slump, grab a snack bar, and usually inhale it in two bites while looking at my phone. I knew that the ingredients were a bunch of artificial additives and emulsifiers, but honestly, I was hungry and usually there was nothing else healthy to eat. It wasn't until our chief scientist Sarah Berry explained the physics of snack foods

on this show that it finally clicked. Highly processed bars are engineered to be eaten fast and release their sugar immediately, which in my case caused a shock spike and then crash in my blood sugar, leading a few minutes later to a collapse in my energy and a spike in my hunger. In my opinion, this is a cynical move by big food companies to make us eat more. I was furious, but Sarah said she thought we could solve this. She came back a year later with the Zoe gut health bar and had done something completely radical. She'd left the natural cell structures of the plants intact.

The first time I tried a sample, I realized you physically cannot rush it. It tastes great, but because the bar preserves that natural food matrix, it's also wonderfully dense and chewy. So it forces me to slow down and savour it. It delivers a huge diversity of over 12 plants. And because it breaks down slowly in your body, you avoid that sudden sugar spike and crash. Plus, both flavours are just delicious. My favourite is, of course, the 70% dark chocolate one. I've got to admit, as a chocoholic, a good, did ask our gut health scientists to make sure we had that option. If you're ready to swap your additive-laden snack bar

for something that's designed to be good for your gut health, head over to zoe.com slash snackbar. That's zoe.com slash snack bar. Your gut will thank you.