Vitamin B3 (niacin, nicotinamide)

Vitamin B3, also called niacin, is the umbrella term for nicotinic acid and nicotinamide. The body takes in both forms with meat, fish, pulses, nuts and wholegrains. Unlike most vitamins, it can also make vitamin B3 itself – from the amino acid tryptophan via the kynurenine pathway. Vitamin B3 is measured in blood as nicotinamide (supplementary profile 1 and single value) or in urine, where it is determined in the evidence profiles on stress, exhaustion and mood together with the other cofactors of neurotransmitter formation. The urine value shows how much the body is currently turning over and excreting.

What vitamin B3 does in the body

From vitamin B3 the body forms NAD and NADP, two of the most important coenzymes of all. NAD accepts electrons in glycolysis, the citric acid cycle and fat breakdown and delivers them to the respiratory chain, where ATP is formed from them. NADPH is needed for building fatty acids and cholesterol and for regenerating glutathione. In addition, enzymes use NAD as a starting material: PARP enzymes use it to repair damaged genetic material, and sirtuins control metabolism and gene activity. Because NAD is constantly broken down in the process, it has to be continuously rebuilt from vitamin B3 or tryptophan.

Low vitamin B3 – what happens in the body?

When too little NAD is formed, tissues with high energy needs and rapid cell renewal suffer most: skin, gut lining and nervous system. Early signs are tiredness, loss of appetite, irritability and sleep problems. A pronounced deficiency is called pellagra and shows as skin inflammation on sun-exposed areas, diarrhoea and disturbances of memory and mood. Reasons can be a one-sided diet, high alcohol consumption, absorption disorders in the gut or a lack of vitamins B2, B6 and iron, which are needed for formation from tryptophan. When tryptophan is increasingly diverted into other breakdown pathways during inflammation, less is also available for the body's own niacin formation.

High vitamin B3 – what happens in the body?

High levels usually result from a generous intake via preparations or fortified foods in the period before the sample; in urine they then mainly show high excretion. The two forms act differently in large amounts: nicotinic acid widens the blood vessels of the skin via its own receptor, leading to a feeling of heat, redness and itching (flush). In very large amounts over a longer period it can strain the liver and raise blood sugar. Nicotinamide does not cause a flush. No harmful amounts arise from a normal diet, because the body converts excess into breakdown products and excretes them via the kidneys.

The interpretation is given in your report.