About supplements

What it is, why it happens and what helps. Contents:

• What are supplements?
• Food first
• Vitamin D
• Folic acid
• Vitamin B12 and plant-based diets
• Omega-3 fats
• Creatine
• Multivitamins
• Magnesium
• Iron and other minerals
• Probiotics
• Herbal supplements
• Choosing good-quality products
• Reading labels
• Supplements through life
• Where to find trusted information
• A simple 4-step plan
• How self-help methods fit in
• FAQs

What are supplements?

Dietary supplements are products taken by mouth that contain nutrients or other ingredients intended to add to the diet. They include vitamins, minerals, fatty acids such as omega-3, amino acids, probiotics and herbal products, in forms such as tablets, capsules, gummies, powders and liquids. Supplements are hugely popular around the world, and choosing well can feel confusing. The good news is that trusted, free information is easy to find. You can explore related topics in our Health hub, including healthy eating, gut health and energy.

Food first

The NHS says most people should be able to get all the vitamins and minerals they need by eating a varied and balanced diet. Food provides fibre, protein and thousands of helpful plant compounds alongside vitamins and minerals. Supplements work best as a top-up for specific needs, rather than a replacement for good food. The Doctor’s Kitchen founder, Dr Rupy Aujla, shares his food-first approach to supplements in Videos.

A colourful plate is a good everyday guide. Different coloured vegetables and fruits provide different vitamins, minerals and plant compounds, so aiming for variety across the week helps cover many needs naturally. Whole grains, beans, lentils, nuts and seeds add B vitamins, magnesium, iron and fibre. Dairy or fortified plant drinks add calcium, and oily fish adds omega-3 fats and vitamin D. When you know what your diet already provides, it becomes much easier to see where, if anywhere, a supplement might help.

Vitamin D

Vitamin D helps the body absorb calcium and phosphate, which keep bones, teeth and muscles healthy. The skin makes vitamin D from sunlight, which is why it is sometimes called the sunshine vitamin. In many countries, there isn’t enough sunlight in autumn and winter to make enough. The NHS advises everyone in the UK to consider taking 10 micrograms of vitamin D a day in autumn and winter, and some people all year round. [1] Low vitamin D is common worldwide. [4] One European study estimated that about 40% of Europeans have low vitamin D levels. [5] A large meta-analysis led by Adrian Martineau found that vitamin D supplements reduced the risk of acute respiratory infections, with the greatest benefit in people who had low levels and those taking daily or weekly doses. [6] A short animation on how the body makes vitamin D is in Videos.

Folic acid

Folic acid is the man-made form of folate, a B vitamin. A Cochrane review found that taking folic acid before and in early pregnancy reduces the risk of neural tube defects such as spina bifida in babies. [7] The NHS recommends taking 400 micrograms of folic acid a day while trying to get pregnant and until 12 weeks of pregnancy. [2] The US Centers for Disease Control and Prevention recommends 400 micrograms a day for anyone who could become pregnant. [8] The NHS explains supplements in pregnancy in Videos.

Vitamin B12 and plant-based diets

Vitamin B12 helps make red blood cells and keeps the nervous system healthy. It is found naturally in animal foods such as meat, fish, eggs and dairy. The NHS notes that people who eat a vegan diet can get B12 from fortified foods, such as some plant drinks and breakfast cereals, or from a supplement. Plant-based eaters may also want to think about iodine, omega-3 fats, iron, calcium and vitamin D. The NHS vegan diet page, in Free resources, is a helpful guide.

Omega-3 fats

Omega-3 fats are found in oily fish such as salmon, mackerel, sardines and herring, and in plant foods such as walnuts, flaxseed and chia seeds. Many people who don’t eat oily fish choose a fish oil or an algae-based omega-3 supplement, which is suitable for vegans. Dr Rhonda Patrick explains omega-3s in Videos.

Creatine

Creatine is one of the most researched sports supplements. It is made naturally in the body and found in meat and fish. The International Society of Sports Nutrition concluded that creatine monohydrate is an effective supplement for increasing high-intensity exercise capacity and lean body mass during training, and that it is safe for healthy people at recommended doses. [3] Researchers are also exploring creatine for healthy ageing and brain health. Andrew Huberman and Rhonda Patrick discuss creatine in Videos. Our guide to building muscle has more.

Multivitamins

Many people take a daily multivitamin as a simple top-up. In the COSMOS-Web study, led by Lok-Kin Yeung and colleagues, older adults who took a daily multivitamin showed better memory after one year than those who took a placebo. [9] ZOE’s discussion with Professor JoAnn Manson, who leads the COSMOS research programme, is in Videos.

Magnesium

Magnesium is involved in hundreds of processes in the body, including muscle and nerve function and energy production. It is found in leafy greens, nuts, seeds, whole grains and beans. Magnesium supplements are popular, often taken in the evening, and come in several forms such as citrate and glycinate. Doctor Alex explains magnesium in Videos.

Iron and other minerals

Iron helps make red blood cells. Good sources include red meat, beans, lentils, dark green leafy vegetables and fortified cereals, and eating vitamin C-rich foods alongside plant sources helps absorption. Iron supplements are usually taken when a blood test shows they are needed. Other minerals such as zinc, calcium, iodine and selenium are also available as supplements. The NIH Office of Dietary Supplements has a free fact sheet for each one.

Probiotics

Probiotics are defined by an international expert panel as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”. [10] They are found in supplements and in fermented foods such as yoghurt, kefir, sauerkraut and kimchi. Different strains have different effects, so it helps to look for products that name their strains. Our gut health guide has more.

Herbal supplements

Herbal supplements such as turmeric, ashwagandha, ginseng and echinacea draw on traditional medicine systems from around the world, including Ayurveda and traditional Chinese medicine. Many are popular for energy, stress and immunity. Our guide to adaptogens covers several of these herbs in detail.

Choosing good-quality products

Quality can vary between brands. Some simple tips:

• Look for independent testing marks such as USP Verified, NSF Certified or Informed Sport, which check that products contain what the label says.
• Check the dose against trusted guidance such as the NHS or NIH fact sheets.
• Choose named forms, such as creatine monohydrate or vitamin D3.
• Buy from reputable sellers such as pharmacies and established shops.

Informed Sport, for example, tests sports supplements for substances banned in sport, which is why it is popular with athletes. USP and NSF check that a product contains the listed ingredients in the stated amounts. A simple, well-labelled product from a trusted brand is often the best choice. Keep a short list of what you take and why, and bring it with you to any health appointment so your care team has the full picture.

Reading labels

Supplement labels list the amount of each nutrient per serving, often with a percentage of a daily reference value. Check the serving size, since some products need two or more tablets a day. Look at the form of each nutrient, the other ingredients, the best-before date and how to store the product. Labels using micrograms (mcg or µg) and milligrams (mg) can be confusing, so compare carefully with trusted guidance.

Supplements through life

Babies and children: the NHS recommends vitamin drops containing vitamins A, C and D for many children from 6 months to 5 years.

Pregnancy: folic acid and vitamin D are commonly recommended.

Older adults: vitamin D and B12 are common considerations, and research on multivitamins and memory is encouraging. [9]

Plant-based eaters: B12 is key, and iodine and omega-3 are worth considering.

Where to find trusted information

Free, reliable sources include the NHS vitamins and minerals pages, the NIH Office of Dietary Supplements fact sheets, and your national health service or public health agency. Pharmacists can give free, personal advice in many countries. All are listed in Free resources.

A simple 4-step plan

1. Start with food. Eat a varied diet with plenty of vegetables, fruit, whole grains and protein.
2. Check the official advice for your stage of life, such as vitamin D in winter or folic acid when planning a pregnancy.
3. Choose quality products with independent testing marks.
4. Review once a year and keep the ones that suit you.

How self-help methods fit in

Supplements work best as part of a healthy lifestyle. Mindful eating helps you enjoy and get the most from your food. Meditation and relaxation support rest and recovery. Yoga and qigong keep you moving, and hypnosis and NLP are popular for building healthy habits. You can see every method we cover in the full list above.

Frequently asked questions

Do I need to take supplements?

Most people can get most nutrients from a varied diet. Some supplements are recommended for specific needs, such as vitamin D in winter.

Should I take vitamin D?

The NHS advises everyone in the UK to consider 10 micrograms a day in autumn and winter. [1]

How much folic acid should I take before pregnancy?

The NHS recommends 400 micrograms a day while trying to get pregnant and until 12 weeks of pregnancy. [2]

Do vegans need B12?

Yes. The NHS says vegans can get B12 from fortified foods or a supplement.

Does creatine work?

The International Society of Sports Nutrition found it effective for high-intensity exercise capacity and lean mass. [3]

Are multivitamins worth taking?

Many people take one as a top-up. One study found better memory in older adults after a year. [9]

How do I choose a good-quality supplement?

Look for independent testing marks such as USP, NSF or Informed Sport, and buy from reputable sellers.

The best videos on supplements

Hand-picked and checked one by one: TED-Ed, the NHS, Sunnybrook Hospital, ZOE, Rhonda Patrick and Dr Rupy Aujla.

How vitamins work

Key supplements

The research

Books on supplements

Free resources

Experts to follow

Get help

If you take regular medicines or have a health condition, check with a pharmacist or doctor before starting a supplement.

Find a therapist or counsellor

• US and Canada: Psychology Today (US) and (Canada) directories.
• UK: BACP therapist directory.
• Australia: APS Find a Psychologist, and Relationships Australia for couple and family services.
• Elsewhere, including Europe and India: ask your doctor or local health service for a referral, and check that anyone you see is registered or accredited where you live.

This hub is for information, not a substitute for medical or psychological care.

Sources

1. NHS, Vitamin D
2. NHS, Planning your pregnancy
3. Kreider et al. (2017), International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine, Journal of the International Society of Sports Nutrition 14:18
4. Holick (2007), Vitamin D deficiency, New England Journal of Medicine 357(3):266-281
5. Cashman et al. (2016), Vitamin D deficiency in Europe: pandemic?, American Journal of Clinical Nutrition 103(4):1033-1044
6. Martineau et al. (2017), Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data, BMJ 356:i6583
7. De-Regil et al. (2015), Effects and safety of periconceptional oral folate supplementation for preventing birth defects, Cochrane Database of Systematic Reviews CD007950
8. CDC, About folic acid
9. Yeung et al. (2023), Multivitamin supplementation improves memory in older adults: a randomized clinical trial, American Journal of Clinical Nutrition 118(1):273-282
10. Hill et al. (2014), The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic, Nature Reviews Gastroenterology & Hepatology 11:506-514

Written by Saj Ali. Last updated 31 October 2026. Spotted an error? Tell us and we will fix it.