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Water Soluble Vitamins
This newsletters covers the water-soluble vitamins, that
is, the B complex group (Thiamin, Riboflavin, Niacin, Pantothenic Acid,
Pyridoxine, cyanoCobalamin, Folic Acid and Biotin) and Vitamin C.
In the March issue we broadly covered nutrition and discussed the role
of the macronutrients (protein, fat and carbohydrate) in the content. However,
the macronutrients cannot function without vitamins.
All forms of life, ranging from simple one-cell organisms like yeasts
or bacteria to the highly complex human being, are based on lots of different
biochemical reactions. Life depends on the chemical changes which:
- Regulate the way we digest food and break it down into simpler components
- Release energy from these simpler components
- Enable this energy to become involved in life's processes
- Enables the brain and nervous system to function
- Build new cells
All biochemical changes in the content need special enzymes. Enzymes enable
optimum functioning of human biochemistry, and are vital to human health.
Most enzymes depend on vitamins, especially the B vitamins. A vitamin
is a chemical compound that cannot be synthesised by the content.
All vitamins are manufactured in the green leaves of plants and then
transferred to the seed of the plant to nourish the next generation. Human
beings directly eat plants, and/or eat animals that have previously eaten
plants, with the vitamins being stored in the flesh.
In the content, water-soluble vitamins must be replaced on a daily basis
because they are easily lost in water and carried away. Some of the B
vitamins are sensitive to strong acid, alkali and light.
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B Complex Vitamins
Thiamin (B1) ~ in the tissues, Thiamin occurs
most commonly as the coenzyme thiamin diphosphate (TDP). This coenzyme
is vital for the release of energy from carbohydrate. A small amount of
thiamin occurs as thiamin triphosphate in nerve tissue. Thiamin distribution
in the content varies, for example the heart muscle contains more thiamin than
brain, liver and kidney tissue, and even more than skeletal tissue (1).
Minor deficiencies may show as Depression, irritability,
lack of concentration and memory loss. Beri-beri is the major deficiency
disease, and is associated with diets high in refined grains and sugar,
usually in countries relying on seasonal crops, where greater individual
energy expenditure arises at the poorest time of the year for food.
Riboflavin (B2) ~ forms the coenzymes flavin
dinucleotide (FAD) and flavin mononucleotide (FMN). These coenzymes are
essential for converting proteins, fats and carbohydrates into energy.
The natural yellow/orange colour of Riboflavin is used to colour children's
drinks and sweets. During supplementation this colour may be transferred
to the urine; it is not toxic and therefore, nothing to worry about.
Minor deficiency symptoms exhibit as soreness of the
mouth and throat, burning and Itching of the Eyes and personality deterioration.
Major deficiency symptoms may show as fissures of the corners of the mouth
or seborrhoeic Dermatitis.
Riboflavin is reasonably stable during food processes
using heat such as canning, dehydration, evaporation and pasteurisation.
Boiling in water results in the vitamin being leached into the water;
this should then be used for soups, gravies and sauces.
Niacin (B3) ~ is converted to its coenzymes
in most tissues. It is a component of nicotinamide adenine dinucleotide
(NAD) and nicotinamide adenine dinucleotide diphosphate (NADP). These
particular coenzymes are involved in many metabolic processes including
glycolysis (the first stage of cellular respiration), tissue respiration
and the metabolism of lipids and Amino Acids.
Minor deficiency symptoms of niacin exhibit as tiredness,
Depression and loss of memory. Pellagra is the major deficiency disease;
this is characterised by horny, scaly Skin, dementia and Diarrhoea.
Pantothenic acid (B5) ~ found in almost every
food, Pantothenic Acid derives its name from the Greek word 'pantos',
meaning everywhere. Pantothenic acid is part of the coenzyme-A molecule
involved in the metabolism of lipids (including fatty acid metabolism),
proteins and carbohydrates; it is also required for the synthesis of cholesterol,
steroid hormones (for example glucocorticoids from the adrenal glands)
Human deficiency is rare and exhibits primarily as
'burning feet syndrome'.
Pyridoxine (B6) ~ rapidly converted in the content
to the coenzymes pyridoxal phosphate and pyridoxamine phosphate which
play an essential role in protein metabolism and also in the release of
energy, lipid metabolism (especially Essential Fatty Acids), central nervous
system activity and haemoglobin production. Pyridoxine is best taken with
other B vitamins together with Magnesium and Zinc.
Pyridoxine deficiency exhibits as Inflammation of the
tongue, a type of sideroblastic Anaemia caused by impaired synthesis of
haem (2). Certain drugs may cause a depletion of vitamin B6.
Cobalamin (B12) ~ is the only vitamin to have
a mineral (cobalt) in its molecular structure. Vitamin B12 is vital for
life; it is needed at a very basic level for the synthesis of DNA and
consequently cell production, especially red blood cells. Vitamin B12
also functions in the metabolism of fatty acids, and in maintaining the
myelin sheath around nerves (1).
Pernicious Anaemia is the condition caused by vitamin
B12 deficiency; this condition is treated with vitamin B12 injected intramuscularly
in large amounts. There is a close relationship between vitamin B12 absorption
and gastric juice production. Gastric juice contains a substance called
'intrinsic factor' which is necessary for the absorption of vitamin B12.
Decreased vitamin B12 in the content may be caused by
inadequate diet, intestinal malabsorption of various forms, and interaction
with some drugs and with alcohol. In the diet, vitamin B12 is found predominantly
in foods of animal origin such as meats and dairy produce (1). It is also
found in very small amounts in yeast extract and some algae.
Folic acid (folate) ~ is needed for many physiological
reactions, especially DNA synthesis. Folic Acid is known as the 'anti-Anaemia'
vitamin; however, its presence can mask vitamin B12 deficiency (3).
To prevent neural tube defects (NTDs) folic acid supplementation
is recommended by the chief medical officer. Amounts of 400?g a day during
normal Pregnancy and 5mg a day (prescribed) in cases where neural tube
defects have been discovered in previous pregnancies (1).
Folate is found widely distributed in the diet, fresh
vegetables are considered a good source of folate but a high intake is
not achieved in most diets. Liver is one of the richest sources of the
vitamin. Folate deficiency is, in itself, quite uncommon (1).
Biotin ~ is obtained through the diet and is
synthesised by bacteria in the colon of humans. Biotin is found in all
foods, predominantly in offal, egg-yolk, soya beans, cereals, meat and
peanuts; to a much lesser degree in fruit and vegetables (1). The availability
of biotin is largely governed by binding agents in food, for example egg-white
contains a substance called avidin which tightly binds to biotin until
the egg is cooked, and the biotin is released as the avidin is destroyed.
Biotin deficiency in adults may result in scaly Dermatitis,
hair loss, Fatigue, nausea or dry scaly Skin (1). Deficiency is more common
in babies, and may lead to seborrhoeic Dermatitis or Leiner's disease
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Vitamin C ~ is considered one of the safest of all the vitamins.
There are many functions of Vitamin C, these include:
- The formation of collagen and other intracellular-matrix structures
- The activity of several enzymes in the liver
- The synthesis of carnitine and noradrenaline, and the metabolism of
Folic Acid, histamine, phenylalanine, tryptophan and tyrosine.
- The absorption of non-haem Iron (from non-meat foods)
- As an antioxidant, vitamin C deals with certain types of free-radical
and helps protect cellular function
Vitamin C deficiency may result in scurvy, and sub-clinical deficiency
in children may be associated with disturbances in growth, in adults with
poor Wound healing and ulceration.
Vitamin C is found in fresh fruit and vegetables and cannot be stored
by the content for any length of time. The vitamin is sensitive to heat,
air, water, (it can easily be washed away) and alkali (bicarbonate of
soda). Good advice suggests using water that vegetables have been cooked
in for gravies, stews and soups (this will also allow any trace minerals
and B vitamins that have leached into the cooking water to be used as
Government recommendations suggest that a minimum of five portions of
fresh fruit and vegetables should be consumed every day to provide important
Antioxidants (5). In nature vitamin C and Bioflavonoids exist together.
Bioflavonoids are Polyphenolic Antioxidants; they include anthocyanadins,
catechins, flavones, kaempferol, Quercetin, hesperidin and rutin. Studies
have shown that they increase the uptake of vitamin C by as much as 35%
higher than that from a citrus extract alone (6).
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- "Human Nutrition and Dietetics", James, Ralph & Garrow et al. Churchill
- Weber & Weber 1964.
- Bailliers Clinical Haematology, 1995, 8;3:679-697.
- British Journal Dermatology, 1994, 131;4:514-420.
- "The Handbook of Dietary Supplements", Pamela Mason, 1995, Blackwell
- American Journal of Clinical Nutrition, 1998, 48:601-604.
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