What are vitamins? Why do they matter? Where can we find them? Are there health risks if we take too much? 

What are vitamins? 

They are organic molecules our bodies need to function effectively, sometimes described asmicronutrients’. That’s because, although they are essential for numerous bodily functions, if we're healthy we normally need only small amounts. You can check how much is needed by looking at the Dietary Reference Value (DRV) on food labels. 

We can usually get most of the vitamins we need if we eat a variety of types of food. Vitamin D is different. It is true that we can get it (as Vitamin D2 or D3) in some foods and it is sometimes added to food like breakfast cereals. However, the main natural source is the action of sunlight on our skin. So we need moderate exposure to the sun (10 – 15 minutes a day) – enough to boost our Vitamin D but not too much, as that might increase the risk of skin cancer. See our separate article on Vitamin D to see who is at particular risk of Vitamin D deficiency and what to do if you live in a country like the UK, where there isn't enough sun to generate Vitamin D from October to March.

Vitamins can be either water soluble (Vitamin A and the B Vitamins) or fat soluble (Vitamins A, E, D and K). If you're on a low fat diet bear in mind that this means your body may be absorbing less of these fat soluble vitamins.

Why do they matter? 

If we don’t get the vitamins our bodies need, then deficiencies can develop and this can lead to diseases. For example: 

Where can we find the vitamins we need? 



Main Food Sources


Vitamin A

Male: 700µg/d

Female: 600µg/d

Offal (e.g. liver), oily fish, green leafy vegetables, dairy products, carrots, red peppers, sweet potatoes, dried apricots

Helps boosts eyesight, helps the growth and repair of bones, gums and teeth and is important for energy. It improves appetite and sense of taste. It can also help skin conditions, as well as ulcers, respiratory and urinary problems.

Vitamin B1

 Male: 1mg/d

 Female: 0.8mg/d

Sunflower seeds, tuna, beans, peas, lentils

Is essential for maintaining a healthy heart and nervous system. 

Vitamin B2

 Male: 1.3mg/d

 Female: 1.1mg/d  

Wheat germ, dairy products, offal, eggs, yeast extract, oily fish and green leafy vegetables

Helps the growth and repair of damaged skin, hair and nails. It is also important for body growth and red blood cell production. IMportant for energy production.

Vitamin B3

 Male: 17mg/d

 Female: 13mg/d 

Fish, chicken, dairy products, eggs, green leafy vegetables

Helps produce energy from the foods we eat. It also helps keep our nerves and muscle tissue healthy. 

Vitamin B5

 Male: 5mg/d

 Female: 5mg/d 

Meat, chicken, liver, yeast extract, egg yolk, nuts, whole grains

All B vitamins help the body convert food to produce energy. Vitamin B5 is critical to the manufacture of red blood cells and is also important in maintaining a healthy digestive tract.

Vitamin B6

 Male: 1.4mg/d



Vitamin B9

Male: 200µg/d

Female: 200µg/d  

Tuna, salmon, chicken, pork, beef, pistachio nuts, walnuts, peanuts, lentils, bananas, whole grains, avacados, dried fruit  

Pulses (like lentils, beans and black eyed peas), spinach, asparagus, avocado, lettuce 

Helps our bodies use and store energy from protein and carbohydrates in the food we eat – and helps create haemoglobin, the substance that carries oxygen around our body.


Required for numerous body functions, including DNA synthesis and repair, cell division and cell growth. Like other B Vitamins it is required for healthy skin, hair, eyes and liver. Especially important for pregnant women, for proper foetal development. 

Vitamin B12


 Female: 1.5µg/d 

Offal, meat, fish, dairy products, eggs, seaweed, fortified breakfast cereal

Important for growth, making red blood cells and keeping the nervous system healthy – deficiency can cause anaemia.

Vitamin C

 Male: 40mg/d

 Female: 40mg/d 

Berries, citrus fruit, kiwi fruit, vegetables, tomatoes, peppers, potatoes, broccoli

Helps protect cells and keeps them healthy; helps maintain healthy connective tissue, which gives support and structure for other tissue and organs; and helps wound healing. Also essential for our immune system.

Vitamin D

 Male: 10µg/d

 Female: 10µg/d 

oily fish, milk, egg yolk, fortified margarine

However, the main natural source of Vitamin D is from moderate exposure of our skin to the sun. 

Vitamin E

 Male: 10mg/d

 Female: 7mg/d 

Nuts, seeds, beans, whole grains, fatty fishes, vegetable oil, green leafy vegetable, avocado

Has anti-oxidant effects (which can prevent or delay some types of cell damage) and is important in helping your body make red blood cells. Also helps the healing process.

Vitamin K

 Male: 70µg/d

 Female 70mg/d 

Dark green vegetables, dairy products, fish liver oil, egg yolk. There are three forms of Vitamin K (K1, K2 & K3).

Essential for blood clotting and to help wounds heal properly. Helps absorption of calcium in our bones.

Are there health risks if we take vitamin supplements?

Medical advice is usually to get the vitamins we need through a varied diet and modest exposure to the sun – and only take vitamin supplements if advised by a doctor for a specific condition. 

That’s because high doses of some vitamins can increase health risks.The Mayo Clinic in the US reported that a study of over 38,000 women in Iowa found those who took multi vitamins appeared to have an increased risk of premature death. The Vitamin supplements they identify as possibly increasing risk are Vitamins A, B3, B6, B9 and Vitamin E. 


  • Eat a variety of food and give your skin moderate exposure to the sun – to make sure you get all the vitamins you need. 
  • Only take vitamin supplements if you are in an ‘at risk’ group (for example if you are pregnant or over 65) and are advised by your doctor.  

Reviewed and updated by Isabel Morgan December 2017. Next review due November 2021.