A Beginner's Guide to Vitamins

Vitamins are essential nutrients that the body needs to function properly but which the body can’t make for itself and therefore they must be obtained from your diet. To ensure that you get all the vitamins that you need you should eat a varied diet. 

Unfortunately, many modern diets – even some that are generally considered to be healthy such as a vegan diet – can be low in some of these essential nutrients.

There are many different vitamins but there are a number that are more commonly checked for by doctors and other healthcare professionals, either because they are commonly low, or because deficiencies in these particular nutrients lead to clinically significant problems.

This is a basic guide to some of the more commonly checked vitamins. 

There are 8 different B vitamins although, confusingly, they are not numbered 1 to 8 because vitamins B4, B8, B10 and B11, have all lost their vitamin status over the years.

The remaining 8 are all important to the body but vitamins B9 and B12 are probably the two that are most commonly checked by doctors.

Where it can be found: 

• Green Vegetables
• Pulses
• Some Breakfast Cereals

Vitamin B9 (otherwise known as folic acid or folate) is found in green vegetables like broccoli, cabbage, peas, and Brussel sprouts, or pulses like chickpeas or kidney beans. Some breakfast cereals are also fortified with folic acid.

Why you need it:

It is used by the body in the process of making red blood cells and so very low levels of folic acid can cause anaemia which may result in symptoms like breathlessness and fatigue. Folic acid is also very important for the development of the neural tube in the foetus. Low levels of folic acid in early pregnancy can cause the baby to be born with a condition called spina bifida and it is for this reason that women are advised to take folic acid supplements pre-conception and in early pregnancy. 

Where it can be found: 

• Meat
• Fish
• Eggs

Vitamin B12 is found in meat, fish, egg, and dairy products so it is fairly common for levels to be low in vegans or vegetarians.

Absorption of vitamin B12 may also be reduced in people with intestinal problems such as coeliac disease, Crohn’s disease, or a condition called pernicious anaemia. Whilst most people can improve their levels of vitamin B12 with oral supplements, those who cannot absorb it properly need to have it replaced by regular injections. 

Why you need it:

Like folic acid, B12 is important for the manufacture of blood and low levels of B12 can also cause anaemia. It is also very important for the health of your nerves, particularly the long nerves that supply sensation to the hands and feet.

People with low B12 may develop symptoms like pain, numbness and tingling in their feet which, if untreated, can progress to affect more of the body, cause muscular weakness, a sore tongue and a range of mental health problems. People with slightly low vitamin B12 levels may have more vague symptoms like fatigue or ‘brain fog’.

Where it can be found: 

• Oily Fish
• Red Meat
• Eggs

Vitamin D is found in oily fish, red meat, eggs and some fortified foods, but we get most of our vitamin D from exposure to sunlight. For this reason it is sometimes called the ‘sunshine vitamin’.

It is also for this reason that low levels of vitamin D are extremely common in the UK. Your risk of vitamin D deficiency is higher if you have dark skin or spend little time outdoors.

Why you need it:

Vitamin D is important to help the body process calcium and phosphate and these three together are relevant to the health of muscles, bones and teeth. 

Very low levels in childhood can lead to rickets which causes bone deformities, and in adults it causes a condition called osteomalacia which causes bone pain and weakness of the muscles, particularly those in the thighs and buttocks. 

In recent decades there has been lots of interest in the other roles that vitamin D plays in the body and it is now thought that vitamin D has key roles in maintaining a healthy immune system and maintaining the health of your brain.

Current advice in the UK is that all adults should consider taking a vitamin D supplement during the autumn and winter as the sun is not strong enough to produce vitamin D effectively. A daily supplement all year round should be considered for children under the age of 5.

These three vitamins are important for your health but aren’t often checked for as most people will get enough of these vitamins in their diet. 

Where it can be found:

• Cheese
• Eggs
• Oily Fish

Good sources of vitamin A are cheese, eggs, oily fish, milk and yoghurt. Liver and pâté are particularly high in vitamin A and eating these too often can actually give you too much vitamin A.

For those who don’t eat meat, fish or dairy, vitamin A can be obtained by eating foods that are high in beta-carotene which the body then converts into vitamin A. This is found in green, leafy vegetables, carrots, sweet potatoes and red peppers as well as in fruits like mango and papaya.

Why you need it:

Vitamin A (sometimes called retinol) is important for the health of your eyes, keeping the immune system healthy and maintaining the health of your skin.

However, regularly taking in high levels of vitamin A can cause your bones to weaken over the course of years, and high levels of vitamin A can harm unborn babies which is why pregnant women are advised not to eat liver and pâté. Taking vitamin A supplements is usually not necessary.

Where it can be found: 

• Citrus Fruits
• Potatoes
• Broccoli

Most people get plenty of vitamin C in their diet, from foods such as citrus fruits, potatoes, berries, and broccoli.

Why you need it:

Vitamin C is important for maintaining the connective tissues, skin, and blood vessels, and to help with wound healing. Historically, vitamin C deficiency caused the disease known as scurvy.

Where it can be found: 

• Green Vegetables
• Vegetable Oils
• Cereal Grains

Vitamin K is found in green, leafy vegetables, vegetable oils and cereal grains. Usually there is plenty of vitamin K in people’s diet and supplements are generally not necessary.

Why you need it:

Vitamin K is involved in blood clotting and people taking the blood thinning agent warfarin need to avoid eating food that is high in vitamin K as this reverses the effect of the medication. 

The best way of monitoring your level of vitamins is to take a blood test, either by visiting a clinic or taking a home testing kit. 

A blood test will assess the levels of the vitamins in the blood, which will tell you if you levels are correct, you have too much in your body or you have deficiencies.

As highlighted above in the various Vitamins, a deficiency or overload can impact your health, so it is important to monitor.

There are a number of other vitamins that are needed for the healthy functioning of the body but the above is an overview of some of the vitamins that are tested for in blood tests or commonly included in multivitamin supplements. 

The best way to get your vitamins is through a varied and balanced diet. 

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