Niacin is one of the more stable B vitamins and is
not degraded or lost by exposure to heat, light, or air.
The following list gives the approximate niacin con-
tent for some common foods:
chicken, light meat, 3 ounces: 10.6 mg
turkey, light meat, 3 ounces: 5.8 mg
beef, lean, 3 ounces: 3.1 mg
salmon, 3 ounces: 8.5 mg
tuna, light, packed in water, 3 ounces: 11.3 mg
asparagus, cooked, 1/2 cup: 1 mg
carrots, raw, 1/2 cup: 0.6 mg
cereal, unfortified 1 cup: 5–7 mg
cereal, fortified, 1 cup: 20–27 mg
pasta, enriched 1 cup cooked: 2.3 mg
bread, whole wheat 1 slice: 1.1 mg
coffee, brewed 1 cup: 0.5 mg
Niacin deficiency
Niacin, like other B-complex vitamins, is used in
enzyme reactions that break down fats, carbohy-
drates, proteins, and alcohol into smaller molecules
that can be used to produce energy or to build up
different molecules necessary to create new cells.
Most of the niacin a person needs must come from
food. The liver does synthesize small amounts of nia-
cin from tryptophan, an amino acid found inprotein.
However, this process is very slow, and it takes 60 mg
of tryptophan to create 1 mg of niacin. Therefore, for
humans to get enough niacin to maintain health, they
must eat niacin-rich foods or take a dietary supple-
ment containing niacin.
Diets that contain little or no niacin over time will
result in a disorder called pellagra. Symptoms of pel-
lagra include cracked, dry, scaly skin (pellagra means
‘‘rough skin’’ in Italian), swollen tongue, sore mouth,
diarrhea, and mental changes. Left untreated, pellagra
is fatal. Symptoms of less severe niacin deficiency
include fatigue, mouth sores, vomiting, headache,
depression, and memory loss.
Pellagra was common in the United States 1940s,
particularly among poor people living in the South
whose diet consisted mostly of corn and cornmeal.
Corn contains niacin, but the niacin is bound to
other molecules in a way that make it unavailable for
use in the body. Many people in Mexico and Central
America survive mainly on a diet of corn products.
However, the tradition of soaking corn in solution
containing alkaline lime before cooking releases the
bound niacin so that it is available to the body. This
explains why people living in Mexico and Central
American rarely develop pellagra despite corn being
a staple in their diet.
In 1938, the United States began a program to add
niacin to bread. The fortification program resulted in
a dramatic drop in the number of people developing
pellagra. Today in the United States, those at highest
risk of developing niacin deficiency are people with
alcoholism, people with anorexia nervosa (self-
starvation), and people with Hartnup’s disease, rare
genetic disorders that affect the ability of the body to
absorb tryptophan.Niacin and cardiovascular disease
Niacin in the form of nicotinic acid when taken in
quantities as large as 2 grams three times a day has
proved successful in rigorous clinical trials in lowering
cholesterol levels in the blood and slowing the devel-
opment of atherosclerosis (hardening of the arteries).
When niacin is taken in these quantities, which are far
beyond the established UL, it should be treated as a
drug, not a dietary supplement, and taken only under
the supervision of a physician. Sometimes niacin is
prescribed along with statin (cholesterol lowering)
drugs. This combination is often more successful in
lowering cholesterol than either medication alone.
Over-the-counter niacin dietary supplements can
be used to treat cardiovascular disease, but many
physicians prefer high-dose prescription niacin.
When sold as a prescription drug, the manufacturing
process is more strictly controlled than it is for niacin
sold as a dietary supplement. Niacin is available in a
variety of immediate-, slow- or extended-release tab-
lets or capsules and as a liquid. It is sold under many
brand names including Niacor, Niaspan, Nicolar, Nic-
otinex Elixir, Slo-niacin, and Novo-Niacin.Niacin and other diseases
Several studies have examined the effect of large
doses of niacin on preventing the development of type
1 (insulin-dependent) diabetes in high-risk individuals.
Nicotinic acid was found to have no effect, but the
results of studies using niacinamide were mixed.
Research continues in this area. Research is also being
done on whether niacin supplementation can decrease
the risk of developing certain cancers. Again, the results
are not clear. The same is true for studies looking at
niacin supplementation as a way of preventing or delay-
ingosteoporosis. Clinical trials are underway to deter-
mine safety and effectiveness of niacin both alone and
in combination with other vitamins and drugs in pre-
venting or treatingcancer, cardiovascular disease, and
dementias such as Alzheimer’s disease. IndividualsNiacin