Which supplements work — and which are a waste | Prof. Tim Spector & Prof. Sarah Berry

Can pills and powders really improve our health? Despite their clinical look, most supplements aren’t tested with the scientific rigour we expect from medical treatments, and many don’t live up to their promises.

Today, we're joined by two of ZOE’s top scientists to uncover the truth. They share groundbreaking new research and reveal the results of a brand new randomized controlled trial that could reshape how we think about supplements and introduce an entirely new kind.

Tim Spector is one of the world’s top 100 most cited scientists, a professor of epidemiology, and ZOE’s scientific co-founder. He’s joined by Dr. Sarah Berry, a world leading expert in large scale human nutrition studies, Professor of Nutrition at King’s College London, and Chief Scientist at ZOE.

By the end of this episode, you’ll have the latest science to help you make informed decisions about supplements and understand what your gut health really needs in 2025.

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Timecodes

00:00 Can supplements actually harm your health?

02:55 Why vitamin pills can do more harm than good

05:45 The truth behind scurvy, rickets, and early nutrition

08:30 Why we’re still stuck in a post-war supplement mindset

11:15 Should you supplement if you’re not deficient?

14:00 What calcium supplements are really doing to your heart

16:50 The real reason food companies add vitamins

19:20 The problem with your diet isn’t deficiency

21:45 Why fixing your diet is harder than it sounds

24:30 Why we need a new kind of supplement

27:10 Whole plants vs powders: why structure matters

29:40 Why plant diversity is the future of gut health

32:10 What’s the difference between prebiotics and probiotics?

35:05 Inside the randomized trial testing a new gut supplement

37:45 The science behind measuring real health impact

40:00 How the gut supplement changed the microbiome

42:30 Why probiotics worked… but much less

45:10 The surprising link between microbes and mood

48:20 How much did cholesterol and inflammation improve?

51:30 Could this reshape how we supplement in the future?

📚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 SpectorFree resources from ZOE

Live Healthier: Top 10 Tips From ZOE Science & Nutrition

Gut Guide - For a Healthier Microbiome in Weeks

Mentioned in today's episode

The Evolution of Science and Regulation of Dietary Supplements: Past, Present, and Future, The Journal of Nutrition (2024)

Supplemental Vitamins and Minerals for Cardiovascular Disease Prevention and Treatment, Journal of the American College of Cardiology (2021)

Long-term multivitamin supplementation and cognitive function in men: a randomized trial, National Library of Medicine (2013)

A diverse high-fibre plant-based dietary intervention improves gut microbiome composition, gut symptoms, energy and hunger in healthy adults: a randomised controlled trial, MedRxiv (2024)

On calcium supplementation:

Dietary calcium intake and risk of fracture and osteoporosis: prospective longitudinal cohort study, British Medical Journal (2011)

Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis, JAMA (2019)

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Episode transcripts are available here.