Niacin is a B-complex vitamin -- B-3 -- available in foods and vital for transforming carbohydrates, proteins and fat into energy. Niacin also exists as a dietary supplement to treat a nutrient deficiency or high cholesterol. B-3 that occurs naturally in foods does not seem to cause side effects or intoxication. But even in small dosages, pills may induce adverse reactions. Supplement niacin only if your doctor prescribes it, taking no more than the recommended dosage.
Poisoning Signs
According to the Centers for Disease Control and Prevention, excessive amounts of niacin can cause mild symptoms such as itching, rash, vomiting, nausea and flushing. Large doses can also provoke severe reactions that include liver intoxication, over-acidification of your body fluids, weakened immunity against infections, fluctuating blood sugar levels and accelerated heartbeat. Hepatitis, a liver inflammation, is also a potential side effect of prolonged use of high dosages of niacin.
Recommended Daily Intake
One way of preventing niacin toxicity is to limit your consumption of the vitamin to the amount considered as sufficient to keep you healthy. The Food and Nutrition Board of the Institute of Medicine recommends that newborns to 6 months of age receive 2 mg of niacin daily from breast milk or formula. At 7 months, their intake should double to 4 mg daily. When a child turns 1 year old, the niacin requirement rises to 6 mg daily and to 8 mg when the child reaches 4 years old. Older kids between 9 and 13 years of age require 12 mg of niacin daily. Starting at age 14 through adulthood, males thrive on 16 mg of niacin every day, and females in the same age group need 14 mg. These daily values are for your total niacin consumption from foods and supplements combined.
Natural Sources
Getting your daily intake of niacin from foods is another way of minimizing side effect risks. But it is worth noting that the Centers for Diseases Control and Prevention recorded at least one case of a niacin overdose from bagels mistakenly enriched with 60 times the usual amount of niacin. As much as possible, get the nutrient from foods that contain the vitamin naturally. Niacin sources include poultry, salmon, beef, legumes and peanuts. Do not substitute your doctor's recommended niacin supplement with foods without discussing it with her first. You may have a medical condition that makes niacin pills the best source of the nutrient for you.
Tolerable Upper Intake
To prevent niacin poisoning, the Food and Nutrition Board of the Institute of Medicine has established upper intake levels, the maximum dosage a person can take every day without experiencing intoxication symptoms. Children between 1 and 3 years of age can tolerate 10 mg of niacin. Four-year-olds can take in as much as 15 mg of the vitamin daily. At 9 years, children can have 20 mg of the nutrient without suffering niacin poisoning. Teenagers tolerate 30 mg from age 14 until their 19th birthday. Adults should not take more than 35 mg of niacin daily.
References
- Linus Pauling Institute; Niacin; Jane Higdon, Ph.D., et al.; June 2007
- "MMWR Weekly": Use of Niacin in Attempts to Defeat Urine Drug Testing--Five States, January--September 2006
- "MMWR Weekly": Niacin Intoxication from Pumpernickel Bagels
- PubMed Health; Niacin; Alison Evert, M.S., R.D., C.D.E., et al.; February 2011
