FOODS HIGH IN NIACIN (VITAMIN B3)
|Beef, pork, liver, eggs, nuts, poultry, milk and dairy products (all are high in cholesterol and/or fat), fish, whole-grain and enriched breads and cereals, beans, peas, potatoes. Cooking destroys some niacin.
|3½ ounces calves’ liver
||16.5 milligrams niacin
|1 cup wheat flakes
||14.7 milligrams niacin
|4 ounces halibut
||10.4 milligrams niacin
|¼ cup peanuts
||10.0 milligrams niacin
|3½ ounces roast turkey
||7.7 milligrams niacin
|1 slice whole wheat bread
||6.0 milligrams niacin
Niacin, also called nicotinic acid or vitamin B3, and its derivative niacinamide, also called nicotinamide, are used by the body to help convert food to energy. Niacin is available in many types of foods (see box above), and a well-balanced diet with a variety of healthful foods should supply all the niacin that your body needs. The recommended dietary allowance (RDA) is 16 milligrams for men over the age of 50, and 14 milligrams for women over the age of 50.
Dietary deficiency of niacin, called pellagra, is rare. If you need to get more niacin, it is better to eat niacin-rich foods than to take a vitamin supplement. You should take niacin supplements to prevent and treat niacin deficiency only when your diet does not provide an adequate amount.
Niacin (nicotinic acid), but not niacinamide, has another use. It can be prescribed as part of a program to lower blood cholesterol or fat, which also includes a modified diet and exercise. The dose for this purpose, 300 milligrams or more, is much higher than the dose as a dietary supplement (10 to 20 milligrams). Taking niacin for this purpose is only an adjunct to weight reduction and exercise, not a substitute.
The adverse effects of niacin, such as blood vessel dilation, which produces intense flushing and itching of the face and upper part of the body, may limit the usefulness of this treatment. One aspirin taken 30 minutes before a dose of niacin may reduce this adverse effect.
Niacin is not useful in treating schizophrenia or other mental disorders unrelated to niacin deficiency. It has not been proven effective in treating any blood vessel diseases nor in treating acne, leprosy, or motion sickness.
If you use niacin without a doctor’s supervision, do not exceed the RDA. Excess niacin, beyond what is needed each day, simply passes through you and is eliminated in the urine without being used by your body. Avoid taking extended-release forms of niacin, since these may damage your liver.
The British Expert Group on Vitamins and Minerals has found that:
Large doses of nicotinic acid [niacin] are associated with a number of adverse effects in man. These have been identified from the use of nicotinic acid in the treatment of hypercholesterolaemia. The effects reported include flushing, skin itching, nausea, vomiting and gastrointestinal disturbance. The effects are dose related and reversible on cessation of treatment. At higher intakes of nicotinic acid over long periods of time, liver dysfunction has been reported. Symptoms such as elevated liver enzymes, elevated bilirubin levels and jaundice have been observed.
Other adverse effects reported include hyperglycaemia and adverse ophthalmological effects such as blurred vision and cystoid macular oedema. No relevant animal data have been reported and the mechanism for nicotinic acid–induced toxicity is unclear.