Do I need a supplement?

vitamin supplements

When we look at the bewildering array of vitamins, minerals and nutritional supplements on supermarket shelves, it’s likely we would question whether we’d be missing out on their potential health benefits by not including them in our diet. But is this true? Are they safe, and if so, how much of them should we be taking?

A dietary supplement is simply a product that ‘supplements’ our diet and provides a specific nutrient or nutrients that may be absent or low in the food we eat. These supplements are usually available in a chewable tablet, pill, capsule, or liquid form and include vitamins, minerals, sports supplements, weight loss aids, herbal products (known as botanicals) and many more besides.

Who benefits?

Some people do benefit from certain supplements on a short or long-term basis, but this does not apply to everyone and in some instances supplements may do far more harm than good. So how do we know if we need one?

Nutrients that are at higher risk of deficiency in the general population include iron, calcium, vitamin D, folate and vitamin B12 (for those following a vegan diet). Individuals who may benefit from taking a supplement include:

  • Young infants
  • Women who are trying to conceive
  • Pregnant and lactating women
  • Individuals who are anaemic
  • Vegetarians and vegans
  • People who avoid certain food groups for health reasons
  • People with medical conditions
  • People who have minimal exposure to the sun (vitamin D)
  • People who rely heavily on processed foods
  • Athletes who consume less than 1500 calories per day
  • Athletes who are unable to meet their high-energy requirements through a balanced diet

couple running

Some key points …..

It is possible to get all the nutrients we need when a variety of healthy foods are included in our daily diet, however supplements can be useful for filling in the gaps. With the exception of vitamin A (from consuming liver), it is very difficult to overdose on vitamins and minerals from food. Problems are far more likely to be caused by supplementation.

A number of key questions can help determine whether a supplement would be helpful:

  • Am I meeting my calorie requirements? – fewer calories means greater risk of several nutrient deficiencies
  • Is my diet sufficiently varied? – a varied diet increases the likelihood of meeting nutrient needs
  • Am I excluding certain food groups?  – the risk of a single or multi vitamin or mineral deficiency increases when important foods are removed from the diet
  • Am I finding suitable alternatives to the food groups excluded from my diet? –suitable alternatives, including some fortified foods (e.g. fortified plant-based milks), provide an important source of nutrients such as vitamin B12, iron, calcium, iodine and vitamin D.
  • Are there plenty of whole foods included in my diet? – a diet high in processed foods is more likely to be deficient in one or several nutrients
  • Do I have higher than average nutrient needs?
  • Is it potentially a waste of money? – many supplements are expensive and many more have no proven benefits, despite claims made on packaging (such as delaying ageing, or boosting the metabolism).
  • Do I think this supplement is going to make my goals reality?

balanced diet

A balanced and varied diet

We can meet our nutrient needs by having a varied balanced diet. This means including:

  • Plenty of fruits and vegetables – go for five-a-day and incorporate a variety of different colours. Suitable choices include fresh, frozen and dried
  • Starchy foods such as potatoes, bread, rice, quinoa and pasta with each meal. Try to choose wholegrain at least 50% of the time
  • Modest amounts of unsaturated fats, such as vegetable oils (olive oil and rapeseed oil, for example) nuts and avocado
  • Some milk and dairy foods (or dairy-free alternatives that are fortified with calcium. Examples include soya, coconut or oat-based products). Adults need 2-3 servings a day to meet the recommended amount of calcium
  • Some beans, pulses, fish, eggs, meat and other rich sources of protein
  • Just small amounts of foods and drinks that are high in salt, sugar and/or fat

Read the label


Dietary supplements can lead to serious side effects, particularly when they are taken with (or instead of) prescribed medication. Many vitamins and minerals interact with each other in the body, enhancing or impairing their absorption or function. Some people should avoid taking nutrients in supplement form (for example, fish liver oil should not be taken by pregnant woman as it contains vitamin A, which can be harmful to babies in large amounts. Vitamin E supplements should be avoided by people with cardiovascular disease as it can increase the risk of further heart attacks).

Unless advised by your doctor, you can ensure you don’t take too much of a vitamin by only taking the recommended dose on the label. If you are taking more than one supplement, make sure you are not taking the same nutrient twice.


Be aware of products sold on the internet as not all meet government guidelines. Wherever you buy, choose a recognized high street retailer or reputable source to ensure the levels of active ingredient is sufficient, and the supplement is safe to take.

Take home message

Most of us can get all the vitamins and minerals we need from a balanced varied diet and through safe exposure to the sun. Supplements certainly have their benefits, but not everyone needs them and it’s important to note that they are not a substitute for a healthy diet. If you think you need a supplement, speak to your doctor, pharmacist, chemist, or dietitian.

About the Author

Zerlina Mastin has a BSc in Nutrition & Dietetics from Kings College London, and an MSc in Public Health Nutrition from the London School of Hygiene & Tropical Medicine. Zerlina has over 10 years experience working in the health and nutrition sector, and is a Registered Dietitian with the British Dietetic Association and Health Professions Council. Zerlina has written a number of our nutrition-related courses and is the author of ‘Nutrition for Dancers’.

Health and Care Professions Council (HCPC) registration number DT14696
British Dietetic Association (BDA) membership number 19508

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