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What are vitamins?

What are vitamins and why do we need them?

What are vitamins?

Vitamins are a group of organic compounds present in small amounts in a variety of natural foods. There are currently 13 recognised vitamins that are essential for supporting the normal functioning of the body: vitamin A, thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9) and cobalamin (B12), C, D, E, K. When a vitamin is absent from the diet, a deficiency will occur. 

We need to obtain vitamins from our diet because the body cannot synthesise them to meet our daily needs. Vitamins are either fat soluble or water soluble depending on whether they dissolve best in either water or lipids. The 4 fat-soluble vitamins are A, D, E and K. When there are excess levels of fat-soluble vitamins in the body, they are stored in fat cells. These vitamins also require fat to be absorbed. In contrast, most water-soluble vitamins are not stored by the body. 

Vitamin E

Vitamin E is an antioxidant important in protecting body tissue from damage caused by unstable substances called free radicals, which are produced by cigarette smoke, sunlight, pollution and chemical reactions in the body. Vitamin E is also important in the formation of red blood cells, keeping the immune system healthy and helps the body to use vitamin K.

How do we get vitamin E?

Vitamin E is a fat-soluble vitamin that must be obtained through our diet as the body is unable to make it. Good sources of vitamin E include vegetable oils, eggs, nuts, seeds, whole grains and green leafy vegetables. Vitamin E supplements are available.

What are the symptoms of a vitamin E deficiency?

In the UK, vitamin E deficiencies are rare and are not usually because of a poor diet. Because vitamin E is a fat-soluble vitamin, a vitamin E deficiency is more likely to occur in those with digestive system problems where nutrients are poorly absorbed including pancreatic disease, gallbladder disease, celiac disease and liver disease. 

Symptoms of a deficiency in vitamin E include muscle weakness, deterioration of muscle mass, vision problems and anaemia.

Vitamin K

Vitamin K refers to a group of fat-soluble vitamins that play a role in blood clotting as well as regulating blood calcium levels and bone metabolism. In the liver, vitamin K is required to produce 4 factors that are necessary for blood to properly clot: prothrombin and also factors VII, IX, and X.

How do we get vitamin K?

The majority of people get all the vitamin K they need by eating a varied and balanced diet. Because vitamin K is a fat-soluble vitamin, any vitamin K in the body that is not needed immediately is stored in the liver for future use. The healthy bacteria that live in the digestive system can produce vitamin K. 

Green leafy vegetables including broccoli and spinach, vegetable oils and fortified cereals are all good sources of Vitamin K. Small amounts can also be found in chicken and dairy products. Vitamin K supplements are also available but monitoring the dose is important as too much can be harmful, so it is advised you speak with your doctor before supplementing vitamin K.

What are the symptoms of a vitamin K deficiency?

Vitamin K deficiency is rare, but can lead to problematic blood clotting and increased bleeding. In those who eat a healthy, varied diet, achieving a vitamin K intake low enough to alter standard clinical measures of blood coagulation is extremely rare. Common symptoms of a vitamin K deficiency include bleeding from the nose and gums, heavy periods, slow wound healing and easy bruising. 

People at risk for developing a vitamin K deficiency include those with chronic malnutrition (such as those who are dependant on alcohol) or conditions that limit absorption of dietary vitamins such as biliary obstruction, celiac disease, ulcerative colitis, regional enteritis, cystic fibrosis, short bowel syndrome, or intestinal resection.

Vitamin K deficiency is most common in newborns and can occur during the first few weeks of infancy due to low clotting factor levels, and low vitamin K content of breast milk. Because of this, a dose of vitamin K given to newborn’s is standard in the UK. 

Vitamin C

Vitamin C which is also known as ascorbic acid is a water-soluble vitamin. The body is unable to make or store vitamin C, so we obtain it through the foods we eat. Alongside being a powerful antioxidant, vitamin C helps the body form and maintain connective tissue, including bones, blood vessels, and the skin as it is required for the biosynthesis of collagen. Vitamin C also helps to strengthen the immune system and aid the absorption of iron in the body. 

How do we get vitamin C?

The best sources of vitamin C are fruits and vegetables. Citrus fruits including oranges and grapefruits as well as peppers, kiwis are all packed full of vitamin C. Other fruits and vegetables such as strawberries, tomatoes and broccoli also contain vitamin C. Prolonged storage of food and cooking can reduce the vitamin C content of food, but fortunately, many foods high in vitamin C are usually eaten raw.

What are the symptoms of vitamin C deficiency?

Vitamin C deficiency causes a range of symptoms in the body including inflammation and bleeding of the gums, dry hair and skin and slow wound healing. People with gastrointestinal conditions and some types of cancer may be more susceptible to developing a vitamin C deficiency. A lack of vitamin C in the diet over a long period of time can lead to a condition called scurvy, a disease resulting from the breakdown of collagen. This condition is rare, as most people get enough vitamin C through their diet. Scurvy affects muscle and bone strength but is easily treated by eating foods rich in vitamin C and taking vitamin C supplements.

Those who supplement vitamin C must be aware that taking an excess, such as 1000 mg daily, may irritate the digestive tract. However, the body excretes what it does not use, so instances of overdosing on vitamin C are rare. 

Vitamin A

Vitamin A is the collective term for a group of fat-soluble retinoids which are essential for many processes in the body. Several genes involved in immune responses are regulated by Vitamin A. Vitamin A also helps maintain the integrity of all surface tissues including the skin, the lining of the respiratory tract, the bladder, the gut and the eyes. Vitamin A is an important part of the rhodopsin molecule, activated when light shines on the retina. The retina then sends a signal to the brain which gives us our sense of vision. Healthy levels of vitamin A in the body play a role in the prevention of macular degeneration, the leading cause of age-related blindness. The antioxidant properties of vitamin A help to fight inflammation through neutralising free radicals that can lead to tissue damage.

How do we get vitamin A?

There are 2 main forms of vitamin A, active vitamin A and beta-carotene. Active vitamin A or ‘retinol’ comes from animal-derived foods and can be used directly by the body. In contrast, the other form of vitamin A, ‘provitamin A’ is obtained from fruits and vegetables in the form of carotenoids, which the body converts to retinol after food is eaten. 

Cheese, eggs, lamb and beef liver, as well as oily fish such as mackerel, salmon and trout, are all great sources of active vitamin A. Coloured fruit and vegetables including spinach, carrots, sweet potatoes, mango, papaya and apricots are all good sources of beta-carotene. The NHS recommends that for adults, (19-64 years) 0.7 mg of vitamin A should be consumed per day for men and 0.6 mg of vitamin A a day for women.

What are the symptoms of vitamin A deficiency?

Vitamin A deficiency is uncommon in Western countries but common in developing countries. Night blindness is one of the earliest signs of a vitamin A deficiency which can potentially lead to permanent blindness if left untreated. Vitamin A deficiency can also cause respiratory infections, weight loss, dry skin and hair. People who suffer from illnesses that affect the way food is absorbed from the gut including coeliac disease, Crohn's disease and cystic fibrosis are at a greater risk of developing vitamin A deficiency. Treatment of vitamin A deficiency often includes increasing consumption of vitamin A-rich foods and taking daily oral vitamin A supplements. 

For those who are pregnant, having large amounts of vitamin A can harm the unborn baby. If you are pregnant or thinking about having a baby, it is recommended that you don't eat liver or liver products, because these are very high in vitamin A. Avoid taking supplements that contain vitamin A and speak with your GP or midwife for further advice. 

The B vitamins

Altogether, there are 8 B vitamins, each with their own purpose and role within the body. The B vitamins are all water-soluble and crucial for cell metabolism, normal functioning of the central nervous system and the formation of red blood cells. All the B vitamins we need should be available through our diet. The B vitamins help with the converting food into fuel and metabolising fats and proteins. Thiamine (B1) in particular is crucial in forming adenosine triphosphate which all cells in the body need.

During pregnancy, vitamin B9 (folic acid) aids the proper development of the baby’s nervous system. Adequate folic acid levels may help to reduce a woman’s risk of having a child with a neural tube defect. Vitamin B12 is needed for DNA production, the normal functioning of the nervous system and the production of energy. 

How do we get the B vitamins?

The 8 different types of vitamin B all come from different food types. 

- Vitamin B1 is found mainly in beef, pork, poultry and offal. Good amounts are also found in whole-grains, legumes and nuts.

- Vitamin B2 is found in foods like almonds, whole-grains, mushrooms, certain dairy products, eggs, brewer’s yeast and some green vegetables.

- Vitamin B3 is found in foods such as eggs, peanuts, fresh fruit and vegetables, red meat and fortified cereals. 

- Vitamin B5 can be found in a wide variety of food types with rich sources including organ meats (liver, kidney, heart, brain), whole grain cereals, eggs, milk, vegetables and legumes. 

- Vitamin B6 is found in foods including some meat, poultry, fish, seafood dairy, lentils, beans, carrots, spinach, bananas, brown rice and whole-grains.

- Vitamin B7: Many foods contain biotin including legumes, lentils, eggs, organ meats (liver, kidney, heart, brain) and dairy products, including milk, cheese, and yoghurt.

- Vitamin B9: Folate is found in a wide variety of foods such as cooked dried beans, peas, and lentils, spinach and asparagus as well as fortified foods such as breakfast cereals. 

- Vitamin B12: is found in virtually all meat products and certain algae such as seaweed. Individuals who follow vegetarian or vegan diets may benefit from supplementing B12. Dried yeast flakes are rich in B12 and can be used in vegetarian/vegan recipes.

What are the symptoms of a vitamin B deficiency?

Symptoms of a deficiency depend on what type of vitamin B you lack. 

- Vitamin B1: It is fairly rare to be deficient in B1, however more common in people with alcoholism, Crohns disease, anorexia or those undergoing dialysis. Symptoms include headaches, nausea, fatigue, depression and abdominal discomfort. It can also make digesting carbohydrates difficult leading to a host of other health problems.

- Vitamin B2: Although rare, vitamin B2 deficiency can occur. Symptoms include anaemia, fatigue, slowed metabolism, nerve damage, a swollen tongue, mouth sores and cracks, skin inflammation, sore throat, swelling of the mucous membranes and changes in mood.

- Vitamin B3: Although extremely rare, vitamin B3 deficiency can occur. Symptoms include fatigue, vomiting, disorientation, memory loss and swelling of the mouth. Strict vegetarians and vegans may be at risk of vitamin B3 deficiency.

- Vitamin B5: symptoms of a vitamin B5 deficiency include burning feet, fatigue, insomnia, vomiting and respiratory infections.  

- Vitamin B6: Although rare, a vitamin B6 deficiency can cause muscle weakness, nervousness, mood changes, difficulty concentrating and short-term memory loss.

- Vitamin B7: Symptoms of a biotin deficiency include red rashes on the skin, brittle and dry hair, dry skin, nausea, fatigue and a burning sensation in the hands and feet.

- Vitamin B9: folate is found in a wide variety of foods such as cooked dried beans, peas, and lentils, spinach and asparagus as well as fortified foods such as breakfast cereals. Patients who have had gastric bypass surgery are at a greater risk of a vitamin B9 deficiency. 

- Vitamin B12: Low levels are seen in people with pernicious anaemia, an autoimmune disease which prevents the absorption of vitamin B12 or through dietary restriction e.g. a vegan diet. Patients who have had gastric bypass surgery are at a greater risk of a vitamin B12 deficiency.