Vitamin B3 - Niacin

Question 1

Vitamin B3 - Niacin

Answer 1

• Vitamin B3 (niacin) is not strictly a vitamin as it can be synthesised by the body from the amino acid tryptophan: 60mg of tryptophan produces 1mg niacin.
• Vitamin B3 is only essential when tryptophan metabolism is altered.
• The two compounds with niacin activity are: nicotinic acid & nicotinamide . The active forms of niacin are: NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate), which are energy carrying molecules.

Question 2

VItamin B3 - Food Sources

Answer 2

• Food sources: Mushrooms, green leafy vegetables, yeast extracts, sunflower seeds, salmon, sardines, peanuts, avocado, meat and poultry. Cooking reduces B3 in foods.
Tryptophan rich foods, e.g. bananas, turkey.

Question 3

Vitamin B3 - Dosage

Answer 3

• Recommendations are stated as niacin equivalents (NE). Equal to the total niacin compounds in food plus 1/60 th of the tryptophan content of the food (i.e. 60mg tryptophan -> body produces 1mg B3).
• Synthesis of B3 from tryptophan requires B2, B6 & iron (cofactors).

Question 4

Niacin Flush

Answer 4

Skin flush & itch due to supplementation. Avoid flush by using initial dose of 25mg (gradually increased) alongside 1g vitamin C

Question 5

Vitamin B3: Absorption and Storage

Answer 5

• Absorption of vitamin B3 is in the small intestine.

* Stored niacin (NAD) is mostly in the liver, heart, muscles and kidney.

Question 6

Vitamin B3 Roles

Answer 6

Energy (ATP) Production
Cardiovascular
Insulin

Question 7

Vitamin B3 - ATP Production - Functions

Answer 7

• The two coenzymes (NAD, NADP) participate in:

• Glycolysis
• Acetyl CoA formation
• Krebs Cycle
• Fatty acid oxidation

Question 8

Vitamin B3: ATP Production - Therapeutic uses

Answer 8

• Fatigue
• Supporting energy production in increased need
• Alzheimer’s

Question 9

Vitamin B3: Cardiovascular - Functions

Answer 9

• Lowers secretion of LDL

* Vasodilatory effects (lowers BP)

Question 10

Vitamin B3: Cardiovascular - Therapeutic Uses

Answer 10

• Hyperlipidaemia

* Cardiovascular disease

Question 11

Vitamin B3: Insulin - Functions

Answer 11

• Glucose tolerance factor (GTF), which plays an important role in the insulin response, employs niacin.

Question 12

Vitamin B3: Insulin - Therapeutic uses

Answer 12

• Insulin resistance (i.e. type 2 diabetes, PCOS)

Question 13

Vitamin B3 Deficiency: Signs and Symptoms

Answer 13

• Severe deficiency (‘Pellagra’): four Ds diarrhoea, dermatitis (characteristic collar rash), dementia, death (within 4-5 years).
Pellagra can occur in diets deficient in both protein and niacin. It is common in Africa, Indonesia and China. In the West, pellagra is associated with homelessness, alcoholism, or anorexia nervosa. Crohn’s or intestinal disease may also lead to deficiency. Pellagra is treated with up to 500mg B3 daily by a doctor.
• Mild deficiency / insufficiency symptoms: Unrelenting fatigue, vomiting, depression, indigestion, canker sores, sensitivity to strong light, red tongue and inflamed gums.

Question 14

Vitamin B3: Toxicity/Adverse Events

Answer 14

Toxicity / Adverse Events:
• Adverse events can occur at high levels: hypotension, hyperuricaemia, flush, hypothyroidism, hepatotoxicity.
• Do not megadose.
• Niacin competes with urate for excretion so supplementation can worsen gout (200mg+/)