The global market for vitamins and dietary supplements, projected to reach over £232 billion by 2028, is facing increasing scrutiny over its efficacy and regulatory oversight. Dr. Nick Tiller, an exercise physiologist, argues in his new book that many supplements are essentially a "con," akin to the "slot machines of the wellness industry" due to their high profit margins and addictive popularity.
According to Tiller, despite the widespread use of supplements—with over six in ten Britons taking them daily—there is scant clinical evidence that they increase lifespan or significantly improve health outcomes. He cites research from the NIH Division of Cancer Epidemiology and Genetics, which tracked over 390,000 adults for two decades and found no difference in mortality rates between supplement users and non-users. In some cases, mortality rates were slightly higher among supplement users, a phenomenon Tiller attributes to people using supplements to "compensate for poor lifestyles."
Further studies reviewed by a team at Johns Hopkins University reportedly reached similar conclusions. An analysis of 450,000 people indicated that multivitamins did not reduce the risk of heart disease or cancer. Another study involving 5,947 men over 12 years found no cognitive benefits from multivitamins, and a study of 1,708 heart attack survivors taking high-dose multivitamins or a placebo showed similar rates of subsequent heart attacks, surgeries, and deaths. Tiller asserts that there is "no benefit from multivitamins on the risk of heart disease, heart attack, cancer, cognitive decline or all-cause mortality, even in people who’d already had heart attacks."
Beyond the lack of proven benefits, Tiller raises concerns about the regulation of the industry. He draws a comparison to the dog food industry, which he claims is more rigidly controlled by over 50 pieces of legislation. In contrast, human dietary supplements in the UK are regulated under the Food Standards Agency, with vendors only required to register as food business operators, a system Tiller suggests is easily navigated. He demonstrated this by registering a fictional online supplement business in less than four minutes, with minimal oversight.
Enforcement of existing regulations is often reactive, Tiller claims, with breaches persisting until a customer complains or falls seriously ill. While making misleading claims or unauthorized medical claims is prohibited, companies can still imply health benefits through vague language such as "promotes recovery" or "supports immunity." Oversight by the Advertising Standards Authority (ASA) is limited, as it primarily investigates complaints and may not prioritize small supplement businesses.
Furthermore, Tiller points out that supplements are not legally required to contain the exact amounts of ingredients listed on their labels, with regulations often allowing deviations of up to 20%. Research published in journals like Scientific Reports and JAMA Internal Medicine has indicated significant discrepancies in the contents of protein powders, vitamin D, selenium, and fish oils, with some products containing less than half of what is advertised. Some studies on fish oils found that fewer than 10% of brands met or exceeded label claims.
Contamination is another significant issue. Tiller cites a case from 2005 where German authorities seized vitamin C, multivitamins, and magnesium contaminated with anabolic steroids. The U.S. Food and Drug Administration maintains a database of over 700 supplements adulterated with hazardous hidden ingredients. Unlike medicines, supplements do not require pre-approval before reaching the market.
Excessive intake of certain vitamins can also be hazardous. For instance, too much vitamin C can lead to cell damage and diarrhea, while high doses of vitamin B6 have been linked to nerve damage, though such warnings are rarely prominent in the wellness industry.
Tiller also notes that much of the research supporting supplement claims is funded by the manufacturers themselves, potentially compromising the objectivity of the findings. He specifically addresses the common claim that supplements can "cure" inflammation, arguing that while chronic inflammation is linked to diseases, eliminating it entirely would be biologically detrimental. He suggests that terms like "inflammation" have been "rebranded as the root of all evil" to drive sales of products like omega-3 and ginger supplements.
Despite his criticisms, Tiller acknowledges that some supplements may warrant consideration. He notes that nearly half the global population is deficient in vitamin D, which can impact bone health and immune function, and that some individuals may benefit from fortified foods or supplements, especially since few natural foods contain significant amounts. He also takes protein powder and creatine to support muscle function. However, his general advice is to consult a doctor or seek impartial advice from sources like the NHS website or the Cochrane Library before taking supplements, and to generally save money rather than purchasing unverified products.