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Updated: 29 Apr 2022

Vitamin supplements you do and don't need

We look at the evidence behind popular supplements, from multivitamins to vitamin C, iron and more to give you the lowdown on who might benefit
Shefalee Loth

Adding a vitamin or mineral supplement into your daily routine can feel like a simple way to protect yourself, but the evidence to support their use in most cases isn't overwhelming.

A study of more than 20,000 adults published in the medical journal BMJ Open in 2020 found no difference in diseases or health conditions between those that took multivitamin supplements and those that didn't.

Despite this supplement sales are booming and the UK industry is worth around £500 million a year. 

However, the same study found that taking supplements can make you feel better. Supplement users reported better overall health compared to non-users by 30%, known as a placebo effect. 

You might think there's no harm in taking supplements if they make you feel better, but they're not risk-free and can be pricey too, so you'll want to know it's worthwhile.

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The supplement you do need: vitamin D

There is one supplement that everyone is recommended to take and that's vitamin D. 

Vitamin D is important for your immune health. It's also important for your bones and teeth and a deficiency means you can't absorb the calcium from food and so can lead to weakened bones, or rickets in children. 

It's found in some food such as oily fish, egg yolks, red meat, liver, mushrooms that have been grown in sunlight and fortified breakfast cereals or spreads, but it is hard to get enough from diet alone. Our main source of vitamin D is from sunshine, but in winter months in the UK you can't get enough from sunshine alone.

Some people are at higher risk of vitamin D deficiency so should take a supplement all year round. These include people with darker skin, people who cover their skin fully when outside and those who are inside a lot.

Find out more in our full Vitamin D guide, including where to get the cheapest supplements and if pills, gummies or sprays are better.

Other important vitamins and minerals


Why you need iron

Iron plays an important role in your red blood cells which carry oxygen your bodies. it's also important for immune health and cognitive function.

If you have an iron deficiency you can feel tired, have a lack of energy, be short of breath, look pale and be more vulnerable to infections.  

Where you find iron

Iron is found in red meat and offal. It's found in smaller doses in chicken and fish. Iron from animal sources is most easily absorbed.

Plant-sources of iron include kidney beans, chickpeas, nuts, dried apricots and fortified breakfast cereals. 

Try to avoid drinking tea and coffee or eating bran-containing cereals alongside iron as they inhibit its absorption.

Do you need an iron supplement?

You should be able to get all the iron you need from your diet even if you don't eat red meat. 

You need higher levels of iron during childhood when you're growing fast. Women also have higher requirements when they menstruate or are pregnant. 

Iron supplements can have unpleasant side effects including constipation and stomach aches.

Vitamin B12

Why you need vitamin B12

Vitamin B12 helps make red blood cells and keeps your nervous system functioning. It also helps release the energy from the food you eat.

Where you find vitamin B12

Vitamin B12 is mainly found in food of animal origin, including meat, fish, milk, cheese and eggs.

Non-animal sources include yeast  extract and fortified breakfast cereals.

Do you need an vitamin B12 supplement?

If you eat the above foods you are unlikely to need a supplement, even if you're vegetarian. 

However if you're vegan you may need a vitamin B12 supplement as a deficiency can leave you tired, lacking energy, feeling confused, having trouble concentrating and having problems with your memory. It can also lead to mouth ulcers.

As we age, our ability to absorb vitamin B12 decreases and deficiencies are common in older adults. If you find you're suffering from the above symptoms, your doctor can check your B12 levels with a blood test and recommend supplements if necessary.

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Should you take multivitamins?

Multivitamin supplements contain a wide range of vitamins and minerals. 

They're often targeted to a specific group or condition although they mostly contain similar ingredients albeit in different doses. Examples include supplements for vegans, over 50s, pregnancy or immune health. 

Multivitamins often contain a wide range of nutrients including vitamins A, C, D, E and the B-vitamins, as well as iron, calcium, magnesium and zinc. 

All these nutrients are easy to find in foods (other than vitamin D) so if you eat a healthy, balanced diet and don't exclude any food groups you're probably getting all the vitamins and minerals you need and so don't need a multivitamin.

Pregnancy supplements

When you're pregnant your folic acid requirement increases and it's hard to get enough from diet alone. 

Folic acid can help prevent neural tube defects in babies, such as spina bifida. So if you're pregnant, or trying to get pregnant the government advises you to take 400 micrograms (µg) of folic acid each day from conception until the end of the 12th week of pregnancy.

You don't need to take a multivitamin for pregnancy but if you do, make sure it's a specific pregnancy one as standard multivitamins contain vitamin A, too much of which can be harmful to a foetus.

Also avoid cod liver oil supplements for the same reason.

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Supplements for vegans

A balanced and healthy vegan diet containing a wide range of fruit and vegetables, beans, nuts, seeds and wholegrains should provide most of the nutrients needed. 

For example it's a myth that vegan diets are lacking in protein. Plant-based sources of protein include lentils, chickpeas, beans, tofu, nuts and seeds.

Meat-replacements such as soya burgers and sausages are also good sources of protein.

However there are some nutrients that can be harder to get from a vegan diet, including iron, iodine and vitamin B12.

Vegan sources of iron

Our bodies don't absorb iron from plant-foods as effectively as iron from animal foods.

Vegan sources of iron include: wholegrains, green leafy vegetables such as kale, peas, lentils and beans, dried fruit and wholegrains. 

Eating these foods alongside a vitamin C source (citrus fruits, potatoes and green leafy veg) will help aid iron absorption.

Vegan sources of calcium

Calcium is found in leafy green vegetables such as kale, figs, almonds, kidney beans, sesame seeds and fortified plant milks.

If you're choosing a plant milk make sure it has calcium added to it and avoid organic plant milks as they aren't fortified.

Vegan sources of iodine

Iodine is also found in fortified plant milks and in seaweed. However seaweed is a very concentrated source so you're advised not to eat it more than once a week.

Vegan sources of zinc

Good plant-based sources of zinc include wheat germ, beans, nuts, seeds, mushrooms and fortified breakfast cereals. 

Vegan sources of Omega-3

 Our bodies convert the essential fats in flaxseeds, walnuts, linseeds and vegan omega-3 supplements made from algae into long-chain omega-3 fatty acids.

Vegan sources of vitamin B12

Vitamin B12 is naturally found in animal foods so it can be difficult to get if you're following a vegan diet. 

However some foods are fortified with it. These include Marmite and other yeast extract spreads, some breakfast cereals and some plant-based milks.

It might be hard to get enough from these (1.5 micrograms a day) so you may want to consider taking a vitamin B12 supplement. 

Supplements for children

Children aged six months to five are advised by the government to take a multivitamin containing vitamins A, C and D each day.

However if your baby is formula fed (and having more than 500ml a day) they don't need a multivitamin as formula milk is already fortified.

Don't give children adult multivitamins as they will contain doses that are too high and don't give more than one supplement at a time as you may double up on some nutrients.

Breastfed babies should take a vitamin D supplement each day from birth, regardless of whether the mother is taking a vitamin D supplement. 

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Supplements you don't need

Beyond vitamin D, if you're healthy and eat a varied and balanced diet including meat, fish, dairy products, beans, pulses, nuts and seeds and your five-a day fruit and vegetables, you're very likely getting all the nutrients you need. 

Popping a pill can feel like an easy option but evidence shows you can't replace a healthy diet with a supplement. For example a diet high in fruit and vegetables is proven to reduce your risk of certain cancers but there's no evidence a multivitamin does the same.

There are other supplements on the market that contain ingredients for which there are no proven health benefits.

Glucosamine supplements

Glucosamine is found naturally in your cartilage, ligaments and tendons and issues with these can cause joint pain.

As a result it's found in supplements for joint health, mobility and flexibility but there's not enough evidence to conclusively prove taking glucosamine helps with any of these.

As a result glucosamine has no authorised health claims. 

Vitamin C, on the other hand, is proven to help support bones and cartilage and as a result glucosamine supplements often also contain vitamin C. 

Therefore any health claims on packaging and advertising relating to bones and cartilage are attributable to the vitamin C and not the glucosamine in the supplement.

Collagen supplements 

Collagen is a protein that keeps your skin strong and elastic but levels decline with age which has provided an opportunity for collagen supplements.

Unfortunately, consuming collagen doesn't mean it will become collagen in your body. When you consume collagen your body breaks it down into amino acids and rebuilds it into the proteins you most need. 

The European Food Safety Authority said that there wasn't enough evidence to support a health claim that collagen could improve skin health.

Co-enzyme Q10

Your bodies make CoQ10 in your livers and it's also found in foods such as meat and vegetable oils.

It helps provide energy to cells and is an antioxidant.

It's found in supplements with claims relating to improved energy levels, brain function, cholesterol or blood pressure however it has no authorised health claims. And these supplements often contain other ingredient such as B-vitamins to enable the product to carry these claims.

Vitamin C

Vitamin C is found in many foods including citrus fruits, strawberries, blackcurrants, peppers, broccoli and potatoes and it's easy to get what you need through diet.

However there are lots of vitamin C supplements on the market that contain 1,000mg - more than 20 times what you need in a day - and people often take these to fight colds. 

While vitamin C plays a role in keeping your immune systems healthy, there isn't currently enough evidence that high-dose supplements can keep a cold at bay.

As Vitamin C is a water-soluble vitamin your body can't store it. Once your body has used what it needs each day it excretes any excess in urine - you're literally flushing your money down the toilet. 

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