B vitamins

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05 August 2015

B vitamins

Vitamin B1 (thiamine)

Vitamin B1, or thiamine, is a vitamin which is important for converting carbohydrates into energy. Carbohydrates are important for providing steady energy. This vitamin also helps with nerve and muscle function by regulating the flow of electrolytes in and out of the muscles.

The average male adult requires 1mg of thiamine each day, while an adult female needs 0.8mg. This should be able to be retrieved through the diet by including certain foods that are particularly good sources of thiamine.

Food source Vitamin B1 content (milligrams, mg)
Marmite, 2 tbsp 3.56
Sunflower seeds, 100g 1.43
Macadamia nuts, 100g 0.71
Soy beans, 100g 0.43
Trout, 100g 0.43

Although it is not common to be deficient in Vitamin B1, it is more likely to occur in those with Crohn’s disease or anorexia, those on kidney dialysis or alcoholics. Initial symptoms include fatigue, low mood, difficulty with coordination and abdominal discomfort. Digestion of carbohydrates will become more difficult, and prolonged deficiency can result in permanent problems with memory and nerve damage.

Research into the effects of taking too much vitamin B1 is limited. However, it may cause an imbalance of other B vitamins in the body, resulting in stomach cramps or pain. It may also result in drowsiness or muscle weakness.

Vitamin B2 (riboflavin)

Vitamin B2, or riboflavin, is not stored in the body, so must be consumed everyday to ensure an adequate intake. It helps the body to break down essential nutrients from protein, carbohydrates and fat. This helps the body maintain an energy supply to muscles. It is also important for red blood cell production.

Riboflavin occurs naturally in many foods, such as eggs and salmon, but is also made synthetically and added to sugary sweets, for example. In this case, it is additive E101, and gives a glowing green or yellow appearance to sweets.

It is not difficult to get an adequate supply of riboflavin into the diet. Adult men need approximately 1.3 mg per day, and adult women require about 1.1 mg per day.

Good sources of Vitamin B2 include:

Food source Vitamin  B2 content (milligrams, mg)
Marmite, 2 tbsp 5.3
Liver, 75g 2.1
Almonds, 75g 0.8
Eggs, 2 0.5
Salmon, 75g 0.4

Vitamin B2 deficiency occurs either as a result of inadequate intake of riboflavin through the diet, or as a result of health conditions including chronic diarrhoea, malabsorption syndromes, liver conditions or alcoholism. Symptoms generally include dry or cracked lips, sensitivity to light and a sore throat.
There have not been reported cases of overdoses of vitamin B2, possibly because excess riboflavin is excreted in the urine.

Vitamin B3 (niacin)

Vitamin B3, also known as niacin, is composed of two main compounds - nicotinic acid and nicotinamide. This vitamin helps the body to metabolise fat, glucose and alcohol. Niacin is also though to promote levels of good cholesterol and reduce levels of bad cholesterol in the bloodstream.

It should be possible to get all the vitamin B3 you need from the diet. For adult men this is approximately 17mg per day, for adult women, 13 mg usually suffices.

The following foods are examples of foods rich in niacin.

Food source Vitamin  B3 content (milligrams, mg)
Yellowfin Tuna, 100g 22.1
Peanuts, 100g 13.8
Mushrooms, 100g 6.3
Sunflower seeds, 100g 8.3
Green peas, 100g 2.1

The chance of taking too much vitamin B3 through natural food sources is unlikely; however, it is more likely if taking an incorrect dose of supplements. Initial reactions may be skin flushing, headaches, nausea and diarrhoea. Long-term consumption of high levels niacin may result in liver and heart problems.

Vitamin B5 (pantothenic acid)

Also called pantothenic acid, vitamin B5, has several important functions, particularly in helping to release energy from the food that we eat. It helps to oxidise fatty acids and carbohydrates, as well as help in the formation of red blood cells. It is thought that correct levels of vitamin B5 helps to reduce stress, by ensuring the correct functioning of the adrenal glands.

Vitamin B5 cannot be stored in the body, so it must be included in the diet each day. However, this should not be difficult, as there are many good natural sources of pantothenic acid.

The recommended daily allowance of this vitamin for adult men is 17mg, and for women is 13mg.

Food source Vitamin  B5 content (milligrams, mg)
Sunflower seeds, 100g 7.06
Trout, 100g 2.24
Eggs, 100g 1.53
Mushrooms, 100g 1.5
Avocado, 100g 1.46

As with many other types of B vitamins, there is not enough evidence to make conclusive comments about the effects of taking too much vitamin B5, particularly as excess amounts of the vitamin are excreted in the urine. It is thought that excess amount of this vitamin in isolation may result in a metabolic imbalance.

Vitamin B6 (pyridoxine)

Vitamin B6, or pyridoxine, has several important functions, including playing a role in almost 100 metabolic enzyme reactions. It also helps with red blood cells production, liver detoxification and the development and proper functioning of the brain and nervous system.

On average, an adult male requires 1.4 mg of vitamin each day, and an adult female requires 1.2 mg. This should be available through the diet, as many foods are natural sources of this vitamin. In addition, several foods are fortified with vitamin B6, such as cereals.

Food source Vitamin B6 content (milligrams, mg)
Sunflower seeds, 100g 1.35
Tuna, 100g 1.04
Pistachios, 100g 1.12
Dried prunes, 100g 0.75
Bananas, 100g 0.37

Cases of consuming too much vitamin B6 through natural dietary sources have not been reported; however it is possible if taking dietary supplements. Initially numbness in the fingers and toes may be noticed, developing into impaired motor function in severe cases.

Vitamin B7 (biotin)

Playing a role in the metabolism of lipids, proteins and carbohydrates, vitamin B7, or biotin, also contributes to healthy hair and skin. It is because of the German words for hair and skin, ‘haar und haut’ that this vitamin is also sometimes called vitamin H.

Some dieticians feel that typical amounts of biotin to be included in the diet should not be advised, as it should not be difficult to maintain a healthy level of this vitamin if eating a balanced diet. However, the recommended daily allowance is 30-50 micrograms in the UK for the average adult.

Food source Vitamin B7 content (micrograms, mcg)
Egg, 100g 21.3
Salmon, 100g 5.86
Strawberries, 100g 1.5
Sweet potato, 100g 1.45
Broccoli, 100g 0.95

There is no evidence that consuming too much vitamin B7 will have toxic effects on the body. Generally, excess biotin will not be stored or absorbed by the body, but excreted through urine.

Vitamin B9 (folic acid)

Vitamin B9 also known as folic acid, or folate in its natural form, is an important B vitamin, working particularly well in conjunction with vitamin B12. It helps with the formation of red blood cells, and reduces the risk of central nervous system defects in unborn babies.

Folic acid cannot be stored in the body but should be readily available in a varied and healthy diet. Adults require approximately 0.2mg of vitamin B9 each day, though some recommend increasing this dose for pregnant women to reduce risk of central nervous system defects in babies. Advice should always be sought from a medical practitioner.

Foods high in folic acid include:

Food source Vitamin B9 content (micrograms, mcg)
Black eyed peas, 100g 210
Spinach, 100g 190
Lentils, 100g 180
Asparagus, 100g 150
Romaine Lettuce, 100g 140

Taking too much vitamin B9 can mask a vitamin deficiency. In the long-term, this can lead to neurological disorders. Very high doses of folic acid can result in sleep disturbances, stomach problems and skin problems.

Vitamin B12 (cobalamin)

Vitamin B12 is sometimes called cobalamin, and is one of the most important vitamins for metabolism of carbohydrates, lipids and proteins. In addition, it is essential for the production of blood cells. It works in conjunction with vitamin B9 to help make red blood cells and aid absorbtion of iron.

The amount of vitamin B12 required is less than many other vitamins, largely because it is the most active. 1.5-2.4 micrograms is the recommended dose for adults, and is available naturally through meat, fish and dairy products. This is of particular interest for vegans, as it is not generally found naturally in the foods that their diet allows, and they may require dietary supplements.

Food source Vitamin B12 content (micrograms, mcg)
Clams, 100g 98.9
Mackerel, 100g 19
Trout, 100g 4.1
Silken Tofu, 100g 2.4
Eggs, 100g 0.72

Too much vitamin B12 is less of a concern than deficiency, largely because there have not been reported cases of excess intake of this vitamin. Some suspect that an acne-like rash may occur, although there is not enough conclusive evidence to back this up. Generally, the body excretes what it does not use.


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