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

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

• 0:01Speaker 00

  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.

• 0:10Speaker 00

  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.

• 0:46Speaker 00

  What exactly are supplements and why were they created in the first place?

• 0:51Speaker 01

  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

• 1:36Speaker 01

  things that are in some chemical form rather than in a food form.

• 1:41Speaker 02

  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.

• 2:22Speaker 02

  So for example, iron deficiency anemia 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.

• 2:33Speaker 00

  And a hundred 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.

• 2:46Speaker 02

  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.

• 3:08Speaker 01

  For example, you know, all these pictures a hundred years ago in Glasgow of kids with bendy joints. This was a vitamin deficiency that now really no longer exists.

• 3:20Speaker 00

  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?

• 3:29Speaker 01

  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 reorganised 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 on to 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.

• 4:15Speaker 01

  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.

• 4:55Speaker 02

  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.

• 5:38Speaker 02

  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.

• 6:01Speaker 00

  So is my analogy a bit like my car needs petrol and it needs oil to function?

• 6:10Speaker 00

  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 pour oil at the car, I'm not making things any better.

• 6:20Speaker 02

  Yeah, and I think as well, our 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, et cetera. 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, et cetera.

• 6:56Speaker 01

  Calcium is another great example. For the last thirty 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,

• 7:36Speaker 01

  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's saying. It's across the board. This is this real misconception about this whole field.

• 7:52Speaker 00

  You're saying they've now done studies on taking calcium as a pill, and it actually increases your risk of heart disease?

• 8:00Speaker 01

  Yes, so it doesn't help fractures, which is what it was supposed to be. I used to prescribe it all the time, giving calcium to menopausal women, for example. It doesn't prevent fractures, and there is increasing evidence that it's associated with heart disease. It 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 ten, hundred times more of it. There's never been shown that that is beneficial.

• 8:44Speaker 02

  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 at 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.

• 9:26Speaker 02

  Supplementing with folic acid reduces the risk of neural tube defects between thirty to seventy-five percent in different populations. People who have iron deficiency anemia, yes, supplementing with iron in the right way.

• 9:38Speaker 01

  B12 works, you know, very well for vegans who struggle to get their B12 levels up. We talked about generalities here. There are obviously subgroups that do still benefit from it.

• 9:47Speaker 00

  So if I understand this rightly, you're saying there are particular groups for whom supplementation makes good sense. And so being pregnant 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, and...

• 10:01Speaker 01

  Or you've got an eating disorder, for example, would be another one.

• 10:04Speaker 00

  So in those particular cases, but in general, we're not in the world that these vitamins were invented for, which is just industrialisation and 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.

• 10:25Speaker 02

  Yes, for most people, the thing that annoys me the most, when I think particularly about the nutribolics 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, preys to someone's insecurity or concern that they might have.

• 11:05Speaker 01

  People think if I'm paying a lot of money for a vitamin or a mineral, you know, 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.

• 11:45Speaker 00

  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 gonna 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?

• 12:09Speaker 01

  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, their blood levels were 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.

• 12:52Speaker 00

  And is that true?

• 12:53Speaker 01

  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. 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

• 13:37Speaker 01

  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.

• 14:09Speaker 00

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