Niacin, along with all the other B vitamins, helps your body get energy from the foods in your diet. In addition to helping with digestion, niacin keeps your skin cells healthy, regulates numerous enzymes and allows nerves to function properly. Even though you need it, if you take too much, you can run into problems.
Amount You Need
Men and women have different niacin recommendations. If you're male, for example, you need 16 milligrams per day. But if you're female, you require just 14 milligrams daily. The only time this differs is for women during childbearing years. Once you become pregnant, you have to get 18 milligrams of niacin every day. Then if you're nursing, aim for 17 milligrams of daily niacin, states the Food and Nutrition Board of the Institute of Medicine.
The majority of nutrients have a tolerable upper intake level, known as the UL. This amount is established by the Food and Nutrition Board of the Institute of Medicine and lets you know the maximum possible amount you can ingest before problems start occurring. All adults of both genders should never have more than 35 milligrams of niacin each day, except under a doctor's supervision. Although niacin is sometimes prescribed in higher doses than this to help with cholesterol levels, the side effects can be serious enough that you need to work closely with your doctor to balance the potential benefits with the dangers.
What Can Go Wrong
Skin flushing is the primary side effect of too much niacin, often occurring on your chest, arms and face. If you're sensitive to niacin, you could experience flushing with as little as 30 milligrams of niacin a day, the Linus Pauling Institute points out. You could have nausea or even vomit from too much niacin. With extreme doses -- over 500 milligrams a day -- you could damage your liver, resulting in hepatitis and jaundice. Large doses of niacin can also affect how insulin works, resulting in low blood sugar, and can cause your blood pressure to drop.
If you're eating plenty of foods high in niacin, you shouldn't have to worry about taking any extra through supplements. Chicken, canned tuna, turkey and salmon are some of the best sources of niacin, giving you between 8 and 12 milligrams of the vitamin in each 3-ounce portion. Your breakfast cereal is another way to get it. Some varieties are fortified with as much as 20 to 27 milligrams of niacin per serving. A slice of whole-wheat bread, a cup of cooked enriched pasta, 1 cup of lima beans or a cup of lentils each provide roughly 1 to 2.5 milligrams of the nutrient. Niacin-rich foods aren't likely to lead to adverse effects, so you don't have to worry about overdosing on foods alone.