Navigating the World of Supplements: What You Need to Know

Start with the basics

This article is general information, not medical advice. It does not recommend any product, brand or dose, and it cannot tell you whether a supplement is right for you. Please talk with a doctor, pharmacist or registered dietitian before starting, stopping or combining supplements, particularly if you take medication, have a health condition, are pregnant or breastfeeding, or are choosing products for a child.

Dietary supplements are products meant to add to the diet, sold as pills, capsules, powders, gummies or liquids. They may contain vitamins, minerals, herbs and other botanicals, amino acids, fiber, probiotics or other ingredients. They are a very broad category, and “natural” or “over the counter” does not mean a product is automatically safe or effective for everyone.

Food comes first

The usual advice from health professionals is that a varied eating pattern is the main way to meet nutrient needs. Foods deliver nutrients together with fiber and other compounds, in forms the body is used to handling. A pill generally cannot replace that. If you are curious about what a varied pattern looks like, our guide to a balanced diet outlines it, and our article on dietary minerals in food shows how many nutrients come from ordinary meals.

That said, there are situations where a professional may suggest a supplement. Examples often mentioned include a diagnosed deficiency, pregnancy, some restrictive eating patterns, certain medical conditions or surgeries that affect absorption, and limited sun exposure in the case of vitamin D. In each case the decision is individual, which is why testing and advice come before buying.

How supplements are regulated

Rules differ by country. In many places supplements are regulated differently from medicines: they are often not required to be proven effective before going on sale, and companies are typically responsible for the safety and accuracy of their own products. That does not mean every product is poor, but it does mean you should not assume that a label claim has been checked. Check what your national health authority says about supplement rules where you live.

Reading a label

A label can tell you quite a lot if you read it slowly.

• Ingredients and amounts. See each ingredient, its form and the amount per serving. Note that a “proprietary blend” may list ingredients without giving the amount of each.
• Serving size. The serving may be more than one capsule, so the amount you actually take can be a multiple of what the front says.
• Other ingredients. Fillers, sweeteners, colors and allergens appear here. The principles in our guide to ingredient lists apply.
• Percent daily value. This compares one serving with a reference amount, but the reference may not match your own needs.
• Warnings. Look for statements about pregnancy, children, medications and existing conditions.
• Independent testing. Some products carry a mark from a third-party testing organization, indicating they were checked for contents. This is not a guarantee of benefit, but it can be more informative than front-of-pack slogans.

It is also worth being skeptical of marketing language. Phrases that promise to cure, detox, melt fat, boost immunity dramatically or “reverse” aging are a warning sign. A supplement should not be presented as treating or preventing disease, and our article on food marketing claims explains how wording can mislead.

Possible interactions and risks

Supplements can act on the body, which is why they can also cause problems.

• Medicines. Some herbs and nutrients can change how prescription drugs work. Blood thinners, antidepressants, diabetes medicines, blood pressure drugs and others are among those that may be affected, so a pharmacist is a useful person to ask.
• Other supplements. Taking several products may mean getting the same nutrient from more than one source without realizing it.
• Too much. Some vitamins and minerals, such as iron, can cause harm in excess, and fat-soluble vitamins can build up in the body.
• Surgery and health conditions. Some products may need to be stopped before procedures, and some are unsuitable for people with kidney, liver or heart conditions.
• Contamination and mislabeling. Products occasionally contain less, more or something other than what the label says.
• Allergies. Ingredients such as shellfish-derived compounds, soy or dairy can appear in unexpected places.

If you experience unusual symptoms after starting a product, stop and speak to a health professional promptly, and consider reporting it to the relevant health authority.

Individual nutrients and herbs

Vitamins and minerals are covered one at a time in other articles, for example vitamin C and vitamin D. Herbal and botanical products can be less predictable because the strength of plant material varies. Even a familiar drink like green tea, which is used in some extract supplements, can behave differently as a concentrated product than as a cup of tea. Because of those differences, it is wise to treat each product as its own decision.

Questions to ask yourself and your professional

1. What exactly am I hoping this will help with, and is there evidence a professional trusts for that?
2. Could a change in food, sleep, activity or routine do the same job?
3. Would a blood test or other check show whether I need this at all?
4. How might it interact with my medications or conditions?
5. How will we decide whether it is working, and when will we stop?

Bring the actual bottles, or photos of the labels, to appointments. A professional can only advise on what they know you are taking.

A balanced view

Supplements are neither miracle products nor automatically harmful. For some people, under guidance, they fill a real gap. For many others, money is better spent on varied food, and on habits such as sleep and movement. When in doubt, ask before you buy, keep things simple, and remember that results vary and are not guaranteed.