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Vitamin A/Retinol
Vitamin B1/Thiamin
Vitamin B12/Cobalamin
Vitamin B2/Riboflavin
Vitamin B6/Pyridoxine
Vitamin C
Vitamin D
Vitamin E
Vitamin K

Vitamin A/Retinol
Vitamin A is an essential vitamin that plays a vital role in the body. Its chemical names include retinol, retinol acetate and retinol palmitate.

How it works
Whilst it is an old wives tale that eating carrots will help you see in the dark, there is a scientific basis to the myth as carrots are rich in Vitamin A, which is needed by the body for the production of rhodpsin, a pigment that enables us to see in the dark. Vitamin A is also an important anti-oxidant and can help prevent the damage caused by excess free radicals. As an anti-oxidant, it plays an important role in the maintaining body's immune system, helping fight bacterial, viral, and parasitic infections. It is also crucial for the development of strong bones, a balanced reproductive system, and healthy skin.

Scientific research has identified the positive role Vitamin A plays as an anti-oxidant in fighting the damage cause by excess free radicals. Research has indicated that if Vitamin A is in good supply, then the action of substances that trigger cancerous changes to cells in the body may be dampened down. Research has also shown that psoriasis and acne may be improved from a diet rich in Vitamin A.
Vitamin A is best absorbed together with a little oil or fat in the diet.

Natural food sources
There are a wide range of foods rich in Vitamin A and these include asparagus, beetroot, butter, calves' liver, carrots, egg yolk, fish roes, margarine and spinach.

Recommended Daily Amounts (RDA)/ Safe Upper Levels (SUL) - Adult intake
The RDA for Vitamin A in adults is 800mcg. The SUL guidance for total Vitamin A intake is no more than no more than 1500mcg from all dietary sources.

Precautions
Vitamin A is a fat soluble vitamin that is stored in the body, so excess intakes build up over time and can become toxic. The guidance provided by the Government on the safe long term intake of Vitamin A should be adhered to. Supplements should be avoided by pregnant women or women planning a pregnancy.

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Vitamin B1/Thiamin
Vitamin B1 is also commonly known by its chemical name of Thiamin.

How it works
Vitamin B1 is essential for the transmission of nerve signals between the brain and the spinal cord. It is also plays a metabolic role, as it is crucial for the workings of certain types of enzymes that make energy available in the body. Body stores are relatively small and so regular intakes are vital.

Scientific research has shown that thiamin is necessary for the glucose in the blood to produce a substance called acetylcholine, which transmits messages between nerves. This is vital for both memory and concentration levels. Research has indicated that a mild deficiency of thiamin may lead to sugar cravings.

Vitamin C may help to prevent thiamin destruction, whilst there is a synergistic effect between all B complex vitamins which means that they tend to work together to enhance one another's absorptionHigh intakes of drinks including coffee, tea and alcohol can adversely affects vitamin B1 absorption and destroy thiamin. Long-term intakes of antacids reduce B1 levels in the body.

Natural food sources
Oranges, peas, pork chop, potatoes, wholewheat pasta and yeast extract are all good sources of Vitamin B1.

Recommended Daily Amounts (RDA)/ Safe Upper Levels (SUL) - Adult intake
The RDA for Vitamin B1 in adults is 1.4mg. The SUL guidance for Vitamin B1 intake is no more than 100mg from all dietary supplements.

Precautions
Excessive daily intakes have been shown to be toxic.

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Vitamin B12/Cobalamin
Vitamin B12 is also commonly known by its chemical name Cobalamin.

How it works
Vitamin B12 is needed to prevent anemia. It plays a vital role in the recycling of key enzymes in the body, which help to maintain the health of nerves and other cells. It is needed to create the covering around nerves that allows for the quick transmission of nerve impulses. Vitamin B12 is also needed for growth when we are young, is involved in controlling the appetite, and is necessary for the production of healthy red blood cells.

Scientific research has identified that Vitamin B12 appears to be indirectly important in the production of certain brain transmitters, such serotonin and dopamine. These chemicals are able to control our moods, sleep patterns, and other psychological functions. More medical science also now believes at Vitamin B12 can affect energy levels.

The mineral calcium, other B complex Vitamins, Vitamin A, Vitamin C, and Vitamin E all work together to improve B12 absorption in the body.

Natural food sources
With the exception of a fermented soy, called tempeh, vitamin B12 is not found in plants but is added to foods as a fortified ingredient. As a result, the body naturally absorbs its requirements from meat-based foods and it takes time for the body to adapt to sourcing its requirements for Vitamin B12 if meat is excluded from the diet. Good natural sources of vitamin B12 include beef, cod, duck, eggs, lamb's liver, liver pate, pheasant and pork.

Recommended Daily Amounts (RDA)/ Safe Upper Levels (SUL) - Adult intake
The RDA for Vitamin B12 in adults is 1mcg. The SUL guidance for Vitamin B12 intake is no more than no more than 2000mcg from long-term use of dietary supplements. Many nutritionists believe that the optimum amount is 5-10mcg for adults. Vitamin B12 works well in conjunction with folic acid and is best taken as a B-complex supplement with food.

Precautions
No side effects of vitamin B12 are known at present. Follow the Government’s guidance on safe upper levels.

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Vitamin B2/Riboflavin
Part of the group of B complex Vitamins, Vitamin B2 is also known as Riboflavin.

How it works
Riboflavin is necessary for red blood cells formation, anti-body production and cell formation. It is needed by the body to turn the calories from protein, fat, and carbohydrate in food into a form that cells can use efficiently. Riboflavin is also needed for the formation of hair, skin, and nails.

Scientific research has shown that while excess riboflavin increases the risk of cataracts, too little may also be a problem. Research also indicates that riboflavin, used in conjunction with iron, can improve anaemia.
In people who are stressed or have diabetes, the amount of riboflavin lost in their urine tends to increase. Women taking the oral contraceptive pill may experience similar effects, while vegans (who consume no animal foods), the elderly, and those who are dieting may have poor intakes. Riboflavin depletion is also common in pregnant women.

Riboflavin is best absorbed when in the presence of other B complex Vitamins and the mineral selenium. Too much iron, zinc, copper, or manganese reduce absorption of riboflavin, as can high intakes of alcohol. Smoking and the contraceptive pill may also deplete levels in the body.

Natural food sources
Natural sources of riboflavin can easily be incoporated into the diet although the exposure of foods to sunlight can destroy this vitamin before being consumed. Dietary sources include beef, cheddar cheese, eggs, lamb's liver, pig's kidney, yeast extract spreads and yogurt.

Recommended Daily Amounts (RDA)/ Safe Upper Levels (SUL) - Adult intake
The RDA for Vitamin B2 in adults is 1.6mg. The SUL guidance for Vitamin B2 intake is no more than no more than 40mg from long-term use of dietary supplements and no more than 43mg from all dietary sources. Many nutritionists believe that the optimum amount is 1.8-2.5mg for adults. Riboflavin is best taken with food as a vitamin B-complex supplement.

Precautions
People with, or who are prone to, cataracts should not take more than 10mg daily because the combination of light, oxygen, and riboflavin increases the risk of cataract development. High doses may increase the risk of magnesium deficiency.

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Vitamin B6/Pyridoxine
Part of the group of B complex Vitamins, Vitamin B6 is commonly known as Pyridoxine, but also has the chemical names Pyridoxal-5-Phosphate (P-5-P) and Pyridoxine hydrochloride

How it works
Pyridoxine is involved in more bodily functions than almost any other single nutrient. It plays a role in both physical and mental health. Vitamin B6 is needed for healthy skin, for keeping the nervous system in good working order, and for the formation of antibodies, which fight infection. Vitamin B6 is used by the body to metabolise protein to make and repair muscle and other tissues, and in the production of enzymes. It also appears to play a role in balancing some hormones, which is why it is popular with women suffering pre-menstrual symptoms. The vitamin also assists in the making haemoglobin.

Scientific research has identified that pyridoxine is needed for the production of serotonin in the brain, a substance that promotes feelings of well-being. People who suffer from depression have been found to have lower blood levels of pyridoxine. Recent scientific research indicates that Vitamin B6 can reduce the symptoms of premenstrual tension, such as mood swings and depression. Combined with other B complex vitamins, pyridoxine may help to improve symptoms of tiredness and fatigue.

As with most B-complex vitamins, absorption of pyridoxine is improved when combined with other B vitamins, and also the minerals magnesium and zinc. Penicillin can bind to pyridoxine, so reducing its absorption. Alcohol, the contraceptive pill, and smoking may also reduce its levels in the body.

Natural food sources
Vitamin B6 is excreted in the urine just eight hours after entering the body, so regular intakes are beneficial. Dietary intake can come from the following foods: banana, beef, brussels sprouts, cabbage, cod, ox liver, turkey, wheatbran and wheatgerm.

Recommended Daily Amounts (RDA)/ Safe Upper Levels (SUL) - Adult intake
The RDA for Vitamin B6 in adults is 2mg. The SUL guidance for Vitamin B2 intake is no more than no more than 10mg from long-term use of dietary supplements. Pyridoxine is the best form in which to take B6.

Precautions
Excessively high levels of intake has been associated with some reports of toxicity.

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Vitamin C
Vitamin C is a water-soluble vitamin, sometimes known but its chemical name, ascorbic acid

How it works
Vitamin C is an important anti-oxidant required for tissue growth and repair, adrenal gland function and healthy gums. It plays an essential role in the body's production and maintenance of healthy collagen, which holds together cells in the skin, gums, and tendons. It also helps the white blood cells to fight infection and is vital for the efficient healing of wounds. An anti-oxidant, vitamin C can help neutralize the potential damaging effect of excess free radicals that trigger ageing and disease.

Scientific evidence suggests that a diet rich in Vitamin C may increase the immune system's ability to fight viral and bacterial infections. Smokers, who tend to have poor vitamin C intakes, have increased need, as do those with increased exposure to other pollutants and people under stress. Clinical trials have found that people with recurrent coldsores have seen a significant reduction in outbreaks when combined with increased intake of Vitamin C.

Bioflavanoids, which are found in fruits and vegetables enhance the absorption of vitamin C, which works best in conjunction with the minerals calcium and magnesium. Smoking, the contraceptive pill, aspirin, and corticosteroid drugs (for treating rheumatoid arthritis) all reduce Vitamin C levels.

Natural food sources
The body cannot store Vitamin C and much of it is excreted in the urine, so regular intakes are beneficial. As a water-soluble vitamin, the method of food preparation can directly impact on the content of Vitamin C, with a detrimental impact if the food is soaked or boiled for a pro-longed period. However, good dietary sources include blackcurrants, broccoli, cabbage, cauliflower, green pepper, guava, kiwi fruit, oranges, papaya and strawberries.

Recommended Daily Amounts (RDA)/ Safe Upper Levels (SUL) - Adult intake
The RDA for Vitamin C in adults is 60mg. The SUL guidance for Vitamin C intake is no more than no more than 1000mg from long-term use of dietary supplements. Many nutritionists believe that 500mg to 100mg daily is required in order to help protect health. As Vitamin C is not stored in the body, a sustained release formulation may be beneficial.

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Vitamin D
Vitamin D is a fat-soluble vitamin. Its chemical names include calciferol, cholecalciferol and ergosterol disease.

How it works
Vitamin D is plays a vital role in encouraging the absorption of calcium and phosphorus from food. It directly increases the rate of mineral deposits on bones. Without enough of it, the body cannot build or maintain strong bones. Vitamin D acts like a hormone, in that it is formed in one part of the body but carries out its function in another. Most of the vitamin D used in the body is formed under the skin through exposure to ultra violet rays from the sun that change it from an inactive form into an active form.

Scientific research has shown that by taking vitamin D supplements daily, elderly people and those at risk of developing osteoporosis may help to increase the beneficial effects of calcium absorption by the body to help strengthen bones and prevent any brittleness developing. Early research showed that young babies could be at risk of developing soft, rickety bones, which bend and bow if there are low levels of vitamin D in their mother's breast milk. Research has also shown that people who suffer from psoriasis may also have low levels of vitamin D.

Anyone who has limited exposure to sunshine may have low levels of Vitamin D. Although research indicates that exposing the face and arms to the sun for fifteen minutes three times a week is an effective way to ensure adequate amounts of Vitamin D in the body. Dietary sources of Vitamin D can be enhanced when combined with fats or oils.

Natural food sources
As indicated above, it is possible to get adequate levels of Vitamin D from sunlight rather than dietary sources. However, good dietary sources include fresh tuna, herring, mackerel, margarine, rainbow trout, salmon and sardines.

Recommended Daily Amounts (RDA)/ Safe Upper Levels (SUL) - Adult intake
The RDA for Vitamin D in adults is 5mcg. The SUL guidance for Vitamin D intake is no more than no more than 25mcg from long-term use of dietary supplements. Many nutritionists believe that 10-20mcg daily is required in order to help maintain good health.

Precautions
Taking vitamin D-rich cod liver oil plus vitamin D supplements could result in excessive intakes. Vitamin D supplements should be kept well out of reach of children as they may be toxic to infants

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Vitamin E
Vitamin E is a fat-soluble vitamin. Its chemical name is tocopherol with variants named alpha, beta, gamma and delta.

How it works
Vitamin E is an anti-oxidant vitamin, helping to neutralize the potential damage caused by excess free radicals in the body. It is particularly important for helping to keep cell walls in good condition and for the healthy maintenance of the skin, nerves, muscles, red blood cells, body circulation, and heart. Vitamin E is unlike other fat-soluble vitamins as it seems to be stored for only a short time in the body, indicating the need for very regular intakes.

There has been extensive scientific research into the beneficial properties of Vitamin E. Clinical trials have shown that increased dietary intake of Vitamin E may lower the risk of heart disease, stroke, and angina by reducing the formation of atherosclerosis plaques on artery walls. Research also indicates that good intakes of vitamin E may play a role in protect against the diseases that can caused by excess free radical damage. Research has shown that Vitamin E may enhance the action of the immune system to fight infection.

Vitamin C and selenium help the action of vitamin E in the body. Excess intakes of iron, copper, and manganese can all reduce vitamin E in the body as can trans-fats in some margarine and processed food, air pollution, and the contraceptive pill.

Natural food sources
Good dietary sources include almonds, avocado, hazelnuts, pine nuts, spinach, sunflower seeds and oil, sweet potato and watercress.

Recommended Daily Amounts (RDA)/ Safe Upper Levels (SUL) - Adult intake
The RDA for Vitamin E in adults is 10mg. The SUL guidance for Vitamin E intake is no more than no more than 540mg (sometimes expressed as 800 International Units) from long-term use of dietary supplements. Many nutritionists believe that 200- 300mg daily is required in order to help maintain good health. The most effective supplement form of vitamin E is d-alpha tocopherol (sometimes known as natural source); avoid dl-alpha tocopherol, which is not as effective

Precautions
When taken by people with vitamin K deficiency, high intakes of vitamin E can adversely affect blood-clotting mechanisms. People with high blood pressure or heart disease should only take high intakes under close medical supervision.

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Vitamin K
Vitamin K exists in three forms; Vitamin K1 known as phylloquinone or phytonactone, Vitamin K2 a family of substances known as menoquinones and Vitamin K3, a synthetic substance known as menadione.

How it works
Vitamin K is needed for the production of substance needed in the body for blood clotting. Bacteria make vitamin K in the colon, from where it is absorbed back across the colon wall into the bloodstream. It is also essential for bone formation and repair, and for healthy teeth. It plays a role in the intestine in promoting a healthy liver function.

Scientific research has shown that Vitamin K can be particularly important to female health and wellbeing. Vitamin K levels have been found to be low in some women with osteoporosis, which increases the risk of bone fractures in later life. Increased dietary intake of Vitamin K by healthy post-menopausal women has been shown to reduce losses of calcium in the urine and improve the calcium binding properties of the hormone which lays calcium onto bones. Vitamin K is needed for the bone-strengthening mineral calcium to be deposited on the bone structure. Research has also shown that women who experience a heavy loss of blood during menstruation could benefit from Vitamin K, which may help to reduce the flow of blood. Low vitamin K levels have been recorded in pregnant women suffering from nausea and vomiting. As Vitamin K is manufactured within the body by bacteria, anyone on a course of antibiotics may find that their body’s ability to produce Vitamin K is reduced.

Natural food sources
Vitamin K can be found in the following foods: alfalfa, broccoli, brussels sprouts, egg yolk, green cabbage, kelp and yogurt.

Recommended Daily Amounts (RDA)/ Safe Upper Levels (SUL) - Adult intake
There is no RDA set for Vitamin K in adults. The SUL guidance for Vitamin K intake is no more than no more than 1000mcg from long-term use of dietary supplements.

Precautions
Excessively high doses of vitamin K should be avoided as they can build up, causing the breakdown of red blood cells and may lead to liver damage and problems such as jaundice in infants and children.

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