Vitamin B3 (Niacin).
Vitamin B3 is found in two forms; as niacin (nicotinic acid) and as  niacinamide (nicotinamide). However, the term "niacin" is used to describe both of them. Vitamin B3 is an essential water-soluble coenzyme, as all the members of the B complex vitamins. Although vitamin B3 can be produced within the body, it is still classified as vitamin and not as hormone. This is because, the production is considered inadequate, since for 1mg of niacin, 60mg of its precursor tryptophan are needed. Either forms of vitamin B3, when used in doses of 20-40mg/day as a nutrient, present the same biological characteristics. However, if taken in increased doses for therapeutic purposes, the pharmacological properties and the side-effects vary. For instance, niacin, in large amounts, acts as vasodilator and results in dilatation of blood vessels. This may decrease blood pressure. Apart from that, gastric disturbances may occur. Other temporary and harmless side-effects may be ranging from a mild, pleasant and warm flush or tingling to extreme skin flushing resembling a sunburn and itching. The nicotinamide form does not cause such symptoms, in similar doses. Niacin helps in blood cholesterol level control. It can reduce LDL, the bad cholesterol, by 15-20% and triglycerides by 10-25%, while it can increase the level of HDL, the good cholesterol, by 15-25%. Nicotinamide does not have any such property, whereas it seems to help in prevention of type 1 diabetes.
Vitamin B3 plays a key role in proper growth, enhancement of fertility, DNA repair, synthesis of hormones and energy production by the metabolism of carbohydrates, fats and proteins. Niacin contributes to good health of the skin, eyes, nervous and digestive system and it can help in prevention of conditions, such as cataract, atherosclerosis and osteoarthritis.
Sources of vitamin B3 (niacin).
Vitamin B3 is contained in beef liver, heart and kidney, pork, poultry, veal, tuna, salmon, swordfish, milk, eggs, brewer's yeast, enriched breads and cereals, nuts, legumes, sunflower seeds, whole grain products, mushrooms, beets, tomatoes, leafy vegetables, broccoli, carrots, sweet potatoes, asparagus, dates and avocados.
Food supplements are available in the market and they are good nutritional sources of niacin. You can try the  button to find vitamin B3 supplements online.
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Vitamin B3 (niacin) deficiency and toxicity.
In the USA, Europe and Australia, alcoholism is the major cause of niacin deficiency. The most common aftermath of vitamin B3 deficiency is the development of pellagra. This is a condition that involves inflamed and scaly skin, digestive problems, diarrhea, depression and mental impairment. Niacin deficiency, very often, is associated with pyridoxine or riboflavin deficiency. Mild vitamin B3 deficiency leads to fatigue, vomiting, reduced metabolic rates which, in turn, results in deterioration of immunity, gain of body weight and perhaps obesity. Prolonged mild deficiency in niacin may result in development of cataract witch is a common sight disorder.
Restoration of a balanced diet and supplementation are the means for treatment  of niacin deficiency. For cataract, laser-surgical treatment is required.
Occasionally, large doses of niacin are prescribed for treatment of osteoarthritis and hyperlipidemia. The latest is a condition that involves increased amounts of lipids, including triglycerides and cholesterol. Therapeutic doses may easily be ranging between 500 and 3000mg/day. In general, the toxicity of vitamin B3 is considered relatively low, since it is water-soluble and consequently, it can readily excreted in the urine. However, large doses may result in side-effects, such as liver inflammation, gastrointestinal ulcers and skin rashness. Quite often, a niacin dosage of 75mg is enough to cause skin flushing. It has been reported that in some cases, low aspirin uptake may ease the skin rashness.
Recommendations for vitamin B3 (niacin).
The recommended dietary allowances (RDAs) for vitamin B3 are 6-12mg/day for children, 14-16mg/day for adolescents and adults and 17-18mg/day for pregnant and breastfeeding women.
The above dosages are recommended, in order to meet the minimum dietary requirements, though. Of course, therapeutic dosages of niacin may be a lot higher, according to a physician's advice. Such advice should be sought for pregnant or breastfeeding women, as well.
In general, supplementation of 200mg per day of pure crystalline niacin is recommended for preventive use in adults.
People, who suffer gout or a liver condition, including those, who consume more than two drinks of alcohol per day, should not take high doses of niacin, unless they have been prescribed for therapeutic reasons.
Niacin should not be combined with tetracycline, without a physician's advice, since vitamin B3 affects the absorption of the antibiotic.
People under diabetes medication and niacin supplementation, should monitor their blood glucose level more often than others, in order to prevent hypoglycemic episodes.
Supplementation of any single vitamin B for a long period of time may lead to significantly imbalanced state of other members of the complex. Thus, a full range of additional supplementation for vitamin B complex is recommended.
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