Vitamin B3

Nicotinic acid is a water-soluble vitamin. The terms vitamin B3 or PP factor (pellagra-preventing factor) for nicotinic acid are now considered outdated and obsolete. Other synonyms for nicotinic acid are niacin, pyridine-3-carboxylic acid. The term niacin refers both to nicotinic acid itself and to its amine derivative nicotinamide. Nicotinic acid was discovered in 1936 and is an essential vitamin. It is a colorless to slightly yellowish powder with the molecular formula C6H5NO2. The E number of nicotinic acid is 375, the CAS number is 59-67-6.

Nicotinic acid is found in all living cells and is stored in the liver. It is an important building block of various coenzymes and acts as a trigger without which there is no proper metabolism and no absorption of proteins, fats and carbohydrates. Nicotinic acid is less sensitive to heat, light and atmospheric oxygen than other B-group vitamins. Nicotinic acid is soluble in water. Its density is 1.473 g/cm³. It melts at 235 to 237 °C and sublimates before it can boil. The molar mass is 123.11 g/mol.

Biosynthesis

There are two forms of biosynthesis of nicotinic acid. Glyceraldehyde phosphate can be converted to nicotinic acid in one step with aspartic acid, the other biosynthesis is from tryptophan via kynurenine to nicotinic acid.

Task/function

Nicotinic acid contributes to energy production in addition to its main role in various metabolic processes such as protein, fat and carbohydrate metabolism. It has an antioxidant effect and is involved in many enzymatic processes. Nicotinic acid is important for the regeneration of skin, muscles, nerves and DNA.

Important mechanisms of action of niacin

Niacin reduced hs-CRP in patients treated orally with niacin for one month (22).
Niacin reduces apoB-100 production (23).
Niacin increases adiponectin levels (24).
Niacin increases leptin levels (24).
Niacin increases the levels of ketones (25).
Niacin reduces HIF-1a expression (26).
Niacin increases PPARa and PPARy expression in adipocytes (26).

Potential health benefits

Niacin can lower LDL cholesterol levels

Niacin has been used to treat high cholesterol levels since the 1950s (1). In fact, studies have shown that niacin can lower bad LDL cholesterol levels by 5 to 20% (2, 3). However, due to its potential side effects, niacin is not a primary treatment for high cholesterol (4). It is therefore primarily used to lower cholesterol levels in patients who cannot tolerate statins (5).

Niacin can increase HDL cholesterol levels

In addition to lowering levels of "bad" LDL cholesterol, niacin also increases levels of "good" HDL cholesterol. Studies show that niacin can increase LDL levels by 15 to 35% (6).

Niacin can lower triglyceride levels in the blood

Niacin can also lower blood triglyceride levels by 20 to 50% (6). It does this by stopping the actions of an enzyme involved in triglyceride synthesis (7). As a result, this also reduces the production of both LDL and VLDL. To achieve these effects on cholesterol and triglyceride levels, therapeutic doses of niacin are required (7).

Niacin may help prevent heart disease

The effects of niacin on cholesterol levels may help prevent heart disease, but recent research suggests that there is an additional mechanism by which niacin has beneficial effects on heart health. Niacin may help reduce oxidative stress and inflammation - both factors involved in atherosclerosis or hardening of the arteries (7). Some research suggests that niacin therapy - either on its own or in combination with statins - may help reduce the risk of heart problems associated with heart disease (8). However, the study results are mixed. A recent review concluded that niacin may not help significantly reduce the risk of heart attacks, strokes or death in people with heart disease or at increased risk (5).

Niacin may help treat type 1 diabetes

Type 1 diabetes is an autoimmune disease in which the body attacks and destroys insulin-producing cells in the pancreas. There is research suggesting that niacin could help protect these cells and even reduce the risk of type 1 diabetes (9, 10). In people with type 2 diabetes, the role of niacin may be more complicated. On the one hand, it may help lower the high cholesterol levels often seen in type 2 diabetics (11). On the other hand, niacin has the potential to increase blood sugar levels. As a result, people who use niacin to treat high cholesterol levels should closely monitor their blood sugar levels (11).

Niacin can improve brain function

The brain needs niacin - as part of the coenzymes NAD and NADP - to get energy and function properly. In fact, impaired concentration and psychiatric symptoms have been linked to niacin deficiency (12). Some types of schizophrenia can be treated with niacin, as it is able to repair the damage to brain cells that occurs as a result of a deficiency (13). Preliminary research shows that niacin may also help to keep the brain healthy in the case of Alzheimer's disease. However, the results are mixed (14, 15).

Niacin can improve skin function

Niacin helps protect skin cells from sun damage, whether it is taken orally or applied to the skin as a lotion (16). Recent research suggests that niacin may also help prevent some types of skin cancer (17). One study found that taking 500 mg of nicotinamide - a form of niacin - twice daily may reduce the rate of non-melanoma skin cancer in high-risk patients (17).

Niacin could reduce the symptoms of arthritis

In an initial study, niacin helped alleviate some symptoms of osteoarthritis, improve joint mobility and reduce the need for non-steroidal anti-inflammatory drugs (18). Another study conducted with laboratory rats found that a niacin injection reduced inflammation associated with arthritis (19). However, while these results are promising, further research is needed.

Niacin can be used to treat pellagra

Severe niacin deficiency leads to a condition known as pellagra (20, 21). For this reason, niacin supplementation is the main treatment for pellagra. Niacin deficiency is rare in the Western world. However, it can occur together with other diseases such as alcoholism or anorexia.

Occurrence

Natural sources of nicotinic acid are high-quality protein foods such as poultry, game, fish, mushrooms, dairy products and eggs. Liver, coffee, wholegrain products, various vegetables and fruit also contain nicotinic acid, although it is generally better utilized by the body from animal products. Vegans cover their requirements with peanuts, wheat bran, dates, mushrooms, brewer's yeast, dried apricots and pulses, for example. To cover the average daily requirement for nicotinic acid, the following amounts of the food in question are sufficient, for example:

100 g beef
150 g turkey meat
300 g mushrooms

Symptoms of deficiency (hypovitaminosis)

Symptoms of deficiency rarely occur as the body can produce nicotinic acid from the amino acid tryptophan. A low-protein diet or absorption disorders can initially lead to unspecific disorders such as loss of appetite, concentration and sleep disorders as well as a certain irritability. Other symptoms of nicotinic acid deficiency are

Skin changes Dermatitis
diarrhea
depression
Inflammation of the oral and gastrointestinal mucous membranes
memory disorders,
reduced performance

Pronounced symptoms of niacin deficiency manifest themselves in the clinical picture of pellagra. In this disease, the skin and mucous membranes change. This is manifested by

Glossitis (raspberry tongue),
burning of the tongue,
excessive pigmentation and
changes in the skin - especially in areas exposed to sunlight.

The appearance of this disease is linked to the introduction of maize in Europe. In the countries of origin of the Aztecs and Mayans, corn was usually placed in lime water after harvesting to release the niacin in the corn. The Spanish conquistadors brought maize to Europe, North America and Africa without following this technique. As a result, entire sections of the population, for whom maize was the main source of nutrition, developed niacin deficiency symptoms.

Consequences of an overdose (hypervitaminosis)

Nicotinic acid is said to be overdosed at a dosage of 1.5 to 3 g per day. An intake of more than 500 mg per day results in a flushing effect that dilates the skin vessels, and an intake of more than 2500 mg per day can cause a drop in blood pressure, dizziness and an increased uric acid content in the blood.

Safety and side effects

There is no danger if niacin is consumed in the amounts found in food (27). However, increased doses in supplement form can cause side effects including nausea, vomiting and liver toxicity (26).

The following are the most common side effects of niacin supplements:

Skin redness: Nicotinic acid supplements can cause redness of the skin around the face, chest and neck as a result of dilation of the veins. There may also be a tingling or burning sensation or pain (28, 29).
Stomach irritation and nausea: Nausea, vomiting, and stomach irritation may occur in response to niacin supplements, especially if sustained-release niacin is taken. Niacin also appears to be associated with elevated liver enzymes (30).
Liver damage: Long-term treatment of high cholesterol levels with niacin could lead to liver damage. This damage appears to be more common with sustained-release niacin supplements, but can also occur with immediate-release supplements (31, 32).
Blood glucose control: High doses of niacin in the range of 3 to 9 grams per day have been associated with impaired blood glucose control with both short-term and long-term use (33, 34).
Eye health: A rare side effect is blurred vision and other negative effects on eye health (35).
Gout: Niacin can increase uric acid levels in the body, which can lead to gout (36).

Nicotinic acid as a medicine

Nicotinic acid is used as a lipid-lowering agent to prevent arteriosclerosis. Nicotinic acid in a dose of 500 - 1000 mg / day lowers the LDL value of cholesterol, increases the HDL value and lowers the triglycerides. The administration of nicotinic acid has so far been limited by its side effects (flushing). It has become better tolerated thanks to a delayed-release form and evening administration. A large study proving the life-prolonging effect of nicotinic acid is still pending.

Need

It is difficult to determine the exact amount of niacin required. This is because niacin can be formed from tryptophan and several vitamins (riboflavin, pyridoxine and folic acid) are involved in its conversion. The function of the vitamin in energy production also influences the niacin requirement. The guideline value is 6.7 mg per 1000 kcal. Accordingly, the DGE recommends a total intake of 18 mg per day for adult men and 15 mg per day for women.

Requirements for sport

30-300 mg per day, taken several times a day with meals.