What are supplements?

Available as tablets, capsules, gummies, sprays or powders, dietary and nutritional supplements are used to complement a diet that may, potentially, be lacking.


Although increasingly popular, it’s important to remember that in the UK there are no requirements for supplements to be licensed or registered and they don’t need a prescription.

Check out our Vitamins and Minerals Information Hub to learn more about key nutrients – including whether you’re getting enough vitamin D to the top 10 healthiest sources of vitamin C, plus vital minerals you need in your diet.

Why do people take supplements?

Many people turn to supplements to enhance or improve their health but it’s important to remember that a well-balanced diet remains the foundation for health and that no supplement can replace the nutritional benefits and advantages of enjoying a varied diet.

That said, there are occasions when some of us may benefit from a supplement. Reasons for this are varied but may include a poor or restricted diet, increased need such as during pregnancy, the use of certain medications, a compromised digestive system due to illness or age and an inability to access the outdoors. Add to this the fact that many of the whole foods we eat, including fruit, vegetables and grains, are less nutritious today than they were 70 years ago, and it’s easy to see why some argue the case for supplementation.

More like this

Popular choices include vitamins B12, C, D and folic acid, minerals such as iron, magnesium and calcium, as well as fish oils and probiotics. Most of us should achieve all our nutritional needs from a healthy, varied and balanced diet but there may be some circumstances when a supplement may be helpful.

Vitamin B12

Why might I be low?

  • If you have a compromised digestion due to conditions like coeliac or Crohn’s disease, you are elderly or you take certain medications
  • If you follow a plant-based or vegan diet

Where can I get B12?

A sign reading 'folic acid' with foods surrounding it

Folic acid

Why might I be low?

  • If you’re a woman planning a pregnancy or in your first trimester
  • If you take certain prescribed medication including those for epilepsy or a diuretic
  • If you have a compromised digestion due to conditions like Crohn’s or coeliac disease
  • If you are elderly
  • If you consume high levels of alcohol

Where can I get folic acid?

Vitamin C

Why might I be low?

Where can I get vitamin C?

Vitamin D

Why might I be low?

  • One in five of us are thought to be low during the winter and early spring months
  • If you have dark skin, cover up for cultural reasons or are housebound, you may be at increased risk

Where can I get vitamin D?


Why might I be low?

  • If you are menstruating or pregnant
  • If you have conditions such as irritable bowel disease (IBD) or coeliac disease
  • If you follow a poor or restricted diet

Where can I get iron?

A sign reading 'Magnesium' with foods surrounding it


Why might I be low?

  • If you have conditions such as Crohn’s or coeliac disease
  • If you have poorly managed type 2 diabetes or a kidney disorder
  • If you are on prescribed medication including diuretics or antacids
  • If you follow a restricted diet, low in vegetables and nuts
  • If you are under extreme stress
  • If you have a high intake of alcohol

Where can I get magnesium?


Why might I be low?

  • If you have a diagnosed milk allergy or lactose intolerance
  • Are post-menopausal
  • Are female and of reproductive age but not menstruating
  • Are a high-performing female athlete
  • Have a restricted diet and are adolescent or elderly
  • If you follow a plant-based diet
  • Are on certain medications

Where can I get calcium?

  • Food sources include dairy foods, fortified plant-based milk alternatives, tinned fish (with bones), green leafy vegetables, dried fruit such as dates, tempeh
  • Our favourite calcium-rich recipes include peanut butter & date oat pots and saag paneer

Omega-3 fatty acids

Why might I be low?

  • If you have a diagnosed fish allergy
  • Are following a restricted diet, including a vegan diet
  • Have a greater need such as during pregnancy or breastfeeding

Where can I get omega-3 fatty acids?

Probiotics & prebiotics

Why might I be low?

  • Those with antibiotic-related diarrhoea
  • If you have irritable bowel syndrome (IBS) or vaginal dysbiosis

Where can I get probiotics & prebiotics?

  • Food sources of probiotics include bio yogurt, kefir, sauerkraut, kimchi, kombucha and miso
  • Food sources of prebiotics include asparagus, banana, garlic and onions, Jerusalem artichokes
  • Our favourite recipes include homemade kefir and kimchi

A hand holding out vitamins surrounded by fresh fruit and veg

Should I take a multivitamin?

Many people wonder if they should take a multivitamin on a ‘just in case’ basis. As the name suggests, a multivitamin is a supplement that contains a range of different vitamins and minerals and sometimes other ingredients, such as herbs. Exact formulations will vary depending on the brand and product you choose.

It’s important to remember that taking a multivitamin will not compensate for poor eating habits and supplementing with high doses of nutrients may be inappropriate and even harmful in some circumstances. Improving your diet with plenty of nutrient-dense, wholefoods is more likely to be an effective approach for your long-term health and wellbeing. That said, those who may benefit include the older age groups for whom a combination of factors such as poor digestion or possibly an inability to get outdoors may leave them lacking in some nutrients such as vitamins B12 and D, as well as the mineral calcium.

For those on a restrictive diet, and this may include vegans and some vegetarians, a multivitamin may be helpful because it may support your intake of the harder-to-get nutrients, including vitamins B12, D and minerals like iodine.

That said, for most of us there is inconsistent evidence to support the value of taking a multivitamin and for those diagnosed with a specific nutrient deficiency it may, depending on your circumstances, be more effective to supplement with just the nutrient you are lacking. Speak to your GP for further guidance.

I am pregnant, should I supplement my diet?

Yes, during pregnancy your need for certain nutrients increases and you’ll need to supplement these. One important vitamin at conception and during pregnancy is folic acid – this vitamin helps to prevent your baby from developing neural tube defects, such as spina bifida. For this reason, mums to be are advised to supplement with 400mcg of folic acid daily from when she plans for a baby until week 12 of her pregnancy. If you have diabetes, sickle cell anaemia or take medication for epilepsy, your folic acid needs may be greater still and you should seek further guidance from your GP or registered dietician.

Another important nutrient during this life stage is vitamin D, which helps your baby’s bones and teeth grow and keeps yours strong and healthy. You should take a supplement with 10mcg of vitamin D daily throughout your pregnancy.

Top tip – dark green leafy vegetables as well as sunflower seeds and wholegrains are useful sources of folate, the natural form of folic acid.

Read our expert guide to learn how to eat well during pregnancy.

I follow a vegan diet, should I take a nutritional supplement?

Certain nutrients may be hard to achieve from a plant-based diet, and these include vitamins B12 and D, iodine and omega-3 fatty acids. Adding fortified foods to your diet and, if necessary, taking a vegan-appropriate supplement(s) may help to complement a balanced, varied vegan diet.

Fortified foods, such as some plant milks, spreads and nutritional yeast flakes, can provide a source of vitamins including B12 or D. If you’re achieving 3mcg of vitamin B12 daily from these sources then you may not need to supplement – if you don’t regularly eat enough of these foods then you may benefit from a supplement providing 10mcg of vitamin B12 daily. Check labels on fortified foods so you know which nutrients are fortified and in what amounts.

Getting adequate amounts of iodine can be tricky, this is because the amount of iodine in plants varies depending on the soil they are grown in. Some, but not all plant milks are fortified with iodine but you will need to check labels. For those who need to supplement, look for a product that provides 150mcg iodine daily.

Nuts and seeds are useful sources of the essential omega-3 fatty acids but they don’t provide the readily absorbable form of this fat. For this reason, a supplement from a micro-algal source may be useful, especially for infants and pregnant people, as well as breastfeeding mums.

Top tip: if you enjoy mushrooms in your diet, put them in a bowl on your kitchen counter and leave them in direct sunlight – this helps enhance their natural vitamin D levels.

Read our guide to find out more about how to follow a balanced vegan diet.

My elderly relative is housebound – should they be taking a supplement?

Elderly people who may be less able to access the outdoors may be at greater risk of a vitamin D deficiency. Unfortunately, very few foods are a good source of this vitamin, making it hard to meet our needs.

The UK Government recommends all adults and even children over the age of one consider a vitamin D supplement providing 10mcg per day during the autumn and winter months (from early October to April). Some groups, such as the housebound, as well as those who cover their skin for cultural reasons and people with darker skin pigmentation, may need to take a vitamin D supplement all year round.

Top tip: taking your vitamin D supplement with your largest meal of the day or with a source of fat may improve absorption.

I’m in mid-life – would a collagen supplement be helpful?

Collagen is a protein found in the body and is important for strong, healthy bones, nails, muscles and joints, it may also help us look more youthful. As we age we become less efficient at producing collagen which also plays a role in keeping our heart healthy.

Several foods provide collagen including beef, pork and fish. However, supplements typically provide a more absorbable, hydrolysed form.

Top tip: there are different types of collagen, so if you’re considering a supplement, check whether it provides the form that is appropriate for your specific needs.

Check out our review on the best collagen supplements

Are supplements safe for everyone?

Supplement use in high-risk groups such as the young, elderly, pregnant and breastfeeding women, patients who are immune-compromised, those due to undergo surgery or who are on prescribed medication should always be discussed with your GP. This is because certain groups may need to avoid some products.

For example, pregnant women should avoid supplements that contain vitamin A in the form of retinol as well as fish liver oil capsules. This is because high levels of this vitamin may be harmful for their developing baby. If you’ve been advised to reduce your salt intake, you should avoid fizzy vitamin supplements because they contain high levels. Similarly, iron supplements may be harmful for people who don’t need them.

Enjoyed this? Now read…

Five nutrients every woman needs
Collagen supplements: do they work?
Am I at risk of calcium deficiency?
Am I getting enough vitamin D?
What are B vitamins?

If you are considering a supplement, first consult your GP to ensure you can do so without risk to your health.

This article was reviewed on 12 February 2024 by Kerry Torrens.

Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including Good Food. Find her on Instagram at @kerry_torrens_nutrition_


All health content on goodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.

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