Five Things to Know Before Buying Supplements

From collagen powders to immunity gummies, supplements are ubiquitous – appearing in Instagram feeds, lining supermarket shelves and crowding bathroom cabinets. They promise improved sleep, radiant skin, better concentration or even a longer lifespan, and are sold as easy answers to modern health concerns.

As a nutritionist, I am regularly asked if supplements justify their cost. My response is always: it depends. Judging by claims online, however, you could be forgiven for thinking they treat almost every condition.

Although certain supplements can be useful in particular situations, they are widely misunderstood and commonly over-marketed. Many consumers also do not appreciate the risks, restrictions and label-based marketing tactics involved.

Here are five points I wish more people understood before purchasing supplements.

1. Choose food before supplements

When a nutrient can be obtained through your diet, that will nearly always be the preferable choice. The UK's Food Standards Agency describes a food supplement as a product "intended to correct nutritional deficiencies, maintain an adequate intake of certain nutrients, or support specific physiological functions".

Put simply, supplements should complement your diet rather than take the place of real food.

Whole foods deliver far more than single, isolated nutrients. Oily fish such as salmon, for instance, supplies omega-3 fats alongside protein, vitamin D, selenium and other helpful compounds. These components work together in ways that are not yet fully understood, and reproducing their combined impact in a supplement is difficult, if not impossible.

Researchers have attempted to identify the “active ingredients” in fruit and vegetables and replicate their effects in tablets, but have not succeeded. Their benefits appear to arise from the food as a whole, rather than from any individual compound.

There are, however, occasions when supplements are needed. Folic acid, for example, is advised before and during pregnancy to lower the risk of neural tube defects in the foetus. Vitamin D is recommended through the winter months, when sunlight is scarce. Those eating a vegan diet may require vitamin B12, as it is found mainly in animal-derived foods.

2. You may be taking more than you think

Taking an excessive amount of a supplement is much easier than consuming too much through food. In the short term, this can cause effects including nausea or diarrhoea. Continued overuse, though, may result in serious harm.

Plenty of people use supplements for years without knowing whether they need them or what amount is excessive. Fat-soluble vitamins – A, D, E and K – are retained by the body instead of being excreted.

Excess vitamin D, for instance, may cause calcium to build up, potentially harming the kidneys and heart while also weakening bones. Large doses of vitamin A can result in liver damage, birth defects during pregnancy and reduced bone density.

Water-soluble vitamins are not necessarily risk-free either: prolonged overuse of vitamin B6 has been associated with nerve damage.

As most people do not have their blood nutrient levels checked routinely, they may not recognise that there is a problem until symptoms develop.

3. Be wary of supplement advice on social media

Spend several minutes online and you are likely to encounter supplements described as “immune-boosting”, “natural” or “detoxifying”. Such phrases may sound persuasive, yet they have no scientific definition. They are marketing language.

The Food Standards Agency states clearly that supplements "are not medicinal products" and "cannot exert a pharmacological, immunological or metabolic action". Nevertheless, many internet claims imply the opposite. This marketing approach, sometimes termed “healthwashing”, suggests supplements possess capabilities that they do not.

Supplements do not undergo the same testing and regulation required for medicines. Consequently, products can be poorly formulated, incorrectly dosed or inaccurately labelled.

The Advertising Standards Authority (ASA) sets rules governing health claims, including those made on social media. Enforcement, however, is challenging, particularly where influencer promotion and affiliate schemes are involved. Multi-level marketing (MLM) schemes create additional complications.

Sellers – who often have no scientific or medical qualifications – market products through personal stories rather than evidence. Although the ASA offers detailed guidance on the way MLM sellers may advertise supplements, those rules are often disregarded, seldom enforced and can fall through regulatory loopholes, allowing some truly astonishing claims to be made.

4. The supplement industry prioritises sales over science

The worldwide supplement market is valued at more than £100 billion. As with every large industry, it is driven by profit and expansion. That shapes both product development and marketing.

If a supplement genuinely worked, doctors would recommend it rather than influencers.

Evidence supports some supplements, though these are usually less glamorous options, including iron and vitamin D.

Many others are promoted using claims that go far beyond the available research, frequently by people without formal nutrition or healthcare training.

5. Supplements are not safe for everybody

A supplement being sold over the counter does not automatically make it safe. Products described as “natural” may still interact with medication or cause damage.

St John’s Wort, which is sometimes used for low mood, may cause dangerous side effects when combined with certain antidepressants, contraceptives and blood-pressure medicines. Vitamin K can affect blood thinners such as warfarin. High-dose iron may cause digestive issues and alter the absorption of certain antibiotics.

The safety of many supplements has not been assessed in pregnant people. Others – including high-dose vitamin A – are known to be harmful during pregnancy and may be transferred through breast milk. If you are pregnant, breastfeeding, taking medicines or managing a health condition, consult a pharmacist, GP or dietitian before beginning a new supplement.

Supplements may help support health where there is a particular need, but they are not a universal remedy. Before paying for a product making grand promises, consider: do I genuinely need it, or would that money be better spent on nutritious food?

Rachel Woods, Senior Lecturer in Physiology, University of Lincoln

This article is republished from The Conversation under a Creative Commons licence. Read the original article.