Vitamin B3 is also known as niacin. Niacin is one of 5 vitamins that cause preventable disease worldwide when deficiencies are present (the others are thiamin, vitamin A, vitamin C, vitamin D). Niacin exists as coenzymes in two forms – nicotinic acid (niacin) and nicotinamide (niacinamide). This complex vitamin is absorbed in the stomach and intestine. What little is stored in the body is stored in the liver. Like most water-soluble vitamins, any excess intake is excreted in urine.
What Does It Do?
Niacin, in the form of its coenzymes NAD+ and NADP+, are involved in oxidation-reduction reactions. Niacin is involved in over 200 cellular metabolic reactions. A lot of these reactions involve the creation of energy for the body by producing ATP (adenosine triphosphate) through the breakdown of sugars (glycolysis) and through the citric acid cycle. Niacin is also involved in breaking down alcohol in the body and in the synthesis of fatty acids. Additionally, niacin participates in DNA repair as well as the synthesis of steroid hormones. Niacin is a very busy vitamin that is used all over the body.
In a few studies, niacin has been shown to increase HDL cholesterol (the good kind) and lower total cholesterol levels. Whether or not niacin can reduce LDL cholesterol (the bad kind) is still in debate. Some studies have also shown that niacin can reduce the risk of atherosclerosis (hardening of the arteries) and help prevent a second heart attack from occurring.
Researchers have been looking into some other medical treatments involving niacin. These studies are not conclusive, but involve using niacin to lower the risk of Alzheimer’s disease, cataracts, osteoarthritis, and type 1 diabetes. As I said, the research results do not currently show definitive results for lowering these risks, but ongoing research is promising in these areas.
Where Can You Find It?
A person can intake niacin as the vitamin itself or by ingesting the amino acid tryptophan, which can be converted into niacin in the body. For each 60 mg of tryptophan consumed, it can be converted into 1 mg of niacin. In order for this conversion to take place, however, an adequate amount of riboflavin (vitamin B2) and vitamin B6 need to be consumed as well.
Approximately 25% of niacin intake in the U.S. comes from poultry. Another 11% comes from enriched flour, bread and bread products. Poultry, dairy and eggs do not have niacin in them at all per se, but they do have tryptophan, which can converted to niacin. Other good sources of niacin include tuna, peanuts, baked salmon, ground beef, raw mushrooms, wheat bran, lean steak, peanut butter, beef liver, corn tortillas, baked cod, asparagus, potatoes, and broiled halibut. From a cooking perspective, unlike some of the other water-soluble vitamins, niacin remains stable under heat, therefore, little is lost in the cooking process.
How Much Do You Need?
The RDA for niacin is shown below:
Infants & Children:
Birth – 6 months 2 mg
7 – 12 months 4 mg
1 – 3 years 6 mg
4 – 8 years 8 mg
9 – 13 years 12 mg
Boys: 14 – 18 years 16 mg
Girls: 14 – 18 years 14 mg
Men: 19 years and older 16 mg
Women: 19 years and older 14 mg
Pregnant women 18 mg
Breastfeeding women 17 mg
Upper Limit 35 mg
What Happens If You Don’t Get Enough?
Cultures that rely on corn as a food staple are susceptible to niacin deficiency. While corn has as much niacin as rice, the niacin in corn is bound very tightly by a protein, making it unavailable in the body. Soaking corn in something alkaline (basic) such as lime water can release the bound niacin and make it available for the body to use. The peoples of Mexico and Central and South America have been soaking corn like this for centuries, which is why they don’t develop deficiencies of this vitamin. Ever had an authentic, homemade corn tortilla that tasted a little like lime? Now you know why! Unfortunately, early European explorers to these regions and U.S. citizens in the early 1900’s didn’t understand the purpose of soaking the corn and became niacin deficient when they didn’t prepare corn in this way. In 1941, the U.S. mandated that niacin be added to grains (enriched grains) in order to eradicate pellagra. It’s not seen much in the U.S. anymore, however, pockets of pellagra are seen today in Southeast Asia and Africa or in areas where there is poverty and malnutrition. Further, chronic alcoholics can develop niacin deficiency.
Niacin deficiency can result in a disease called pellagra. Pellagra is a horrible disease that causes widespread damage in the body (no surprise given the number of bodily reactions needing niacin). It causes skin to have a red, rough, rash-like appearance that worsens with exposure to sunlight. The effects of pellagra are known as the 3 Ds – dementia, diarrhea, and dermatitis. Early symptoms include loss of appetite, weight loss, intolerance to cold, and general weakness. Without proper treatment, death can result.
A genetic cause of niacin deficiency can manifest itself as Hartnup’s disease. In this disease, tryptophan cannot be broken down or absorbed into the body in order to be converted into niacin.
What Happens If You Take Too Much?
Although niacin is a water-soluble vitamin, there is a Tolerable Upper Limit because mega doses of this vitamin can cause skin flushing, itching, and gastrointestinal tract issues (such as nausea and vomiting). For adults, the UL is 35 mg/day from supplemental niacin and/or fortified and enriched foods. As a note, this UL does NOT include niacin obtained naturally from foods.
Medical professionals have prescribed niacin in relatively high doses over the RDA in order to decrease LDL cholesterol, increase HDL cholesterol, or even reverse the progression of atherosclerosis. Do NOT do this on your own, however. To make sure this treatment is right for you, the advice needs to come from a medical professional.
As always, the best way to consume any nutrient in order to avoid over- or under-consumption is to consume a wide variety of foods, in a wide variety of colors, and eat according to MyPlate.
Until next time, remember that… there are no excuses when it comes to your health!