Vitamin B3, Niacin
Niacin is also known as nicotinic acid, although the latter term is avoided in order not to evoke an association with tobacco and thus make people suspicious. Niacin, can be made in the body by the conversion of tryptophan, an essential amino acid. Niacin is required for normal cellular function and functions as a component in well over fifty different chemical reactions in the body to produce energy, process fat, cholesterol and carbohydrates, as well as to manufacture sex and adrenal hormones.
Severe deficiency of niacin and tryptophan results in pellagra, a disease characterized by cracked, scaly dermatitis, mental confusion and diarrhea. On average, a person needs approximately 15-18 milligrams niacin on a daily basis. Supplemental niacin is available as either nicotinic acid or niacinamide. Each form has different applications. In the nicotinic acid form, niacin is an effective agent for lowering blood cholesterol levels, while in the niacinamide form, niacin is useful in treating arthritis. High doses - 2 to 6 grams per day - of either forms of niacin should be monitored by a physician as they may result in liver disorder, stomach ulcers, and glucose intolerance.
Rich Food Sources of Niacin
Rich food sources of niacin as nicotinic acid include liver and other organ meats, eggs, fish, and peanuts.. All of these foods are also rich in tryptophan.
Vitamin B3 Quick Calculator
So, what daily foods can supply the recommended 18 milligrams of vitamin B3 and give you that blissful peace of mind and a great feeling of being full of energy? Here is a selection of some foods:
- Chicken breast, roasted (1/2, app. 3 oz) - 62% RDA
- Light meat tuna, canned in water (3 oz) - 55% RDA
- Lamb liver, simmered (3 oz) - 54% RDA
- Fresh tuna, cooked (3 oz) - 45% RDA
- Turkey white meat, roasted (3 oz) - 31% RDA
- Peanuts, with skin (3.5 oz) - 90% RDA
- Peanuts, without skin (3.5 oz) - 75% RDA
- almonds (3.5 oz) - 19% RDA
- Egg, whole - 14% RDA
What May Cause Niacin Deficiency?
1. Poor nutrition - A generally poor balance of amino acids in the diet can cause pellagra. Corn contains very small amounts of tryptophan.
2. Chronic alcoholism - Excessive intake of wine and beer may cause pellagra and zinc
3. Poor absorption of niacin in the intestines - Niacin deficiency or pellagra may result from complications of certain diseases, such as Crohn's disease (inflammation of the digestive tract resulting in diarrhea).
4. Prescription drugs - Some medications such as isoniazid, pyrazinamide ehtionamide, 6-mercaptopurine, hydantoins, phenobarbital and chloramphenicol may interfere with absorption of niacin and cause its deficiency.
5. Restriction diet - Vegetarian diets can lead to multiple vitamin B deficiencies, including niacin deficiency.
6. Other vitamin deficiencies - The conversion from tryptophan to niacin is more difficult in people with vitamin B2 (riboflavin) and B6 (pyridoxine) deficiency. It is very important to maintain a balance of all vitamins B.
Bioavailability of Niacin
Bioavailability is the percentage of a nutrient absorbed from the food. Nutrients ingested but not released during the digestive process for absorption are of no nutritional value. Some plant-derived foods contain niacin in a chemically-bound form which prevents its release from absorption in the body. For example, niacin in corn is chemically bound and is not absorbed in the intestines. In addition, various nutrients and food components interfere with the bioavailability of vitamins. For instance, pellagra frequently affects people who eat sorghum (millet) as a main food which contains high concentrations of leucine. Although this grain contains adequate tryptophan, excessive concentrations of leucine interfere with tryptophan metabolism and subsequent niacin synthesis. Niacin in ordinary cereal food has only 30% bioavailability, while the bioavailability of niacin from meat, milk, beans and eggs is excellent. Since the total intake of nutrients is generally closely linked with total caloric intake, people with decreased energy demands should eat foods with higher vitamins bioavailability than those who consume more calories and spend more energy on a daily basis.
Niacin Deficiency and Cancer Risk
A deficiency of any of the micronutrients: folic acid, vitamin B12, vitamin B6, niacin, vitamin C, vitamin E, iron, or zinc, mimics radiation in damaging DNA: if you do not eat minimum five portions of fruit and vegetables a day as advised, your body is exposed to harmful effects compared to those of radiation. Folate deficiency causes extensive incorporation of uracil into human DNA (4 million/cell), leading to chromosomal breaks. This mechanism is the likely cause of the increased colon cancer risk associated with low folate intake. Some evidence suggest that vitamin B12 and B6 deficiencies also cause high uracil and chromosome breaks. There are also various sources of evidence that niacin levels may increase cancer risk, including leukemia and skin cancer. Remedying vitamin and mineral deficiencies can dramatically improve your health at a relatively low cost.