Where it comes from: Niacin is a form of Vitamin B3 and is found in many good-for-you foods such as yeast, meat, fish, milk, eggs, green vegetables, beans and cereal grains. Niacin (nicotinic acid) also comes in prescription form and as dietary supplements.
What it'll do for you: B vitamins are essential for fueling your body. "All B vitamins help the body convert food (carbohydrates) into fuel (glucose), which is burned to produce energy," says Sari Greaves, RD spokesperson for the American Dietetic Association and nutrition director at Step Ahead Weight Loss Center in Bedminster, NJ. They also help the body metabolize fats and protein, help the nervous system function and are necessary for healthy skin, hair, eyes and liver. But niacin is most often touted for lowering LDL cholesterol (the bad kind), protecting against cardiovascular disease and boosting HDL cholesterol (the good kind). Here, a closer look regarding those main benefits:
- Lowers LDL cholesterol and protects against cardiovascular disease
"Niacin may help prevent medical problems caused by high cholesterol and fat clogging the blood vessels," explains Greaves. A group of researchers formed The Coronary Drug Project and followed 8,341 men between 1966 and 1975. The men—ages 30 to 64—had all suffered from a heart attack or heart condition before the study. Compared to the placebo group, the group that took three grams of nicotinic acid each day experienced an average of a 10 percent reduction in total blood cholesterol, a 26 percent decrease in fat-holding triglycerides, a 27 percent reduction in recurrent nonfatal heart attacks and a 26 percent reduction in strokes. Although the niacin supplements didn't decrease the total deaths from cardiovascular disease during the six-year study, a follow up nine years later found nearly an 11 percent reduction in total deaths. Other major cardiovascular trials have also found nicotinic acid—in combination with other therapies—to be beneficial in men and women.
- Increases HDL cholesterol
To prevent the adverse side effects associated with high doses of nicotinic acid, the B vitamin is often used in combination with other medications. A recent study found that nicotinic acid (2 to 3 grams per day) combined with a cholesterol-lowering drug (simvastatin) results in an increase of HDL levels. Results, however, are dose-dependant. Another study found that a very low dose of niacin (100 mg daily) increased HDL cholesterol by only 2.1 mg per deciliter of blood, and the combination had no effect on LDL cholesterol, total cholesterol, or triglyceride levels.
Some case studies report that taking niacin and cholesterol-lowering statins may result in muscular disease but more research is needed.
Suggested intake: Niacin recommendations are given in NE, or niacin equivalents. "That's because it comes from two sources: niacin and the amino acid, tryptophan, part of which converts to niacin," says Greaves. "The recommendation for niacin is tied to energy (calorie) needs—adult males should strive for 16 milligrams NE daily." Bigger doses—up to 100 mg—are often prescribed for patients with high cholesterol, but this should be at the advice of your doctor.
Eating protein-rich foods is the best way to get adequate niacin. "Choose lean sources of protein such as skinless poultry, fish, round/loin cuts of beef, natural peanut butter and legumes," Greaves says. Niacin is also added to many grain products; On a food label 10 to 19 percent of the Daily Value is considered a good source of niacin while 20 percent or more of the Daily Value is considered an excellent source. To help you quantify other foods, Greaves provided this handy chart:
- 3 ounces of skinless turkey breast, roasted = 6.0 mg NE
- 2 tablespoon of peanut butter = 4.0 mg NE
- 3 ounces cooked codfish = 2.0 mg NE
- 1 enriched flour tortilla = 1.5 mg NE
- 1/2 cup enriched spaghetti, cooked = 1.0 mg NE
- 1/2 cup cooked black-eyed peas or boiled lima beans = 0.5 mg NE
A niacin deficiency isn't likely for people who consume adequate amounts of protein-rich foods. However, pellagra is caused by a chronic lack of niacin and symptoms include diarrhea, mental disorientation and skin problems.
Associated risks/scrutiny: Consuming excess amounts from supplements (though not likely food) may cause flushed skin, rashes or liver damage. It could also result in a dangerous rise in glucose levels in diabetics. The Tolerable Upper Intake Level (UL) is 35 mg daily for adults. "Self-prescribing large doses of niacin to lower blood cholesterol may lead to adverse effects—some of which may not include cholesterol-lowering benefits," Greaves adds. If your doctor prescribes niacin, take it in the recommended dosage.