Comprehensive Guide to Vitamins by Dr. James Meschino - HTML preview

Vitamin B3 – Niacin (Nicotinic Acid)

Introduction

Niacin (nicotinic acid), like riboflavin, is directly involved in the production of energy at the cellular level enabling the body to convert carbohydrate, fat, and protein into ATP energy. Niacin, in the form of NAD, transfers hydrogen molecules from these sources to riboflavin (FMN), which in turn transfers hydrogen in a stepwise fashion to the cytochromes within the mitochondria. These transfers allow parcels of energy to be released which re-couples ADP with inorganic phosphate to form more ATP – the ultimate source of energy to power biological reactions in the body. Niacin, which occurs naturally as nicotinic acid, is easily converted by the body to its active form, nicotinamide. It is frequently administered as nicotinamide for therapeutic reasons, since nicotinic acid acts as a vasodilator and can produce severe flushing and itching. Because the body can convert tryptophan (an amino acid) into niacin, some nutritionists do not consider Niacin to be an essential dietary nutrient as along as tryptophan intake is adequate. Approximately 60 mgs of dietary tryptophan can be used to synthesize 1 mg of Niacin in the body. It is involved in more than 200 enzyme reactions and is essential for healthy skin, tongue, digestive tract cells, and the formation of red blood cells.

Absorption and Metabolism

Niacin is absorbed in the small intestine. Little storage occurs in the body and, therefore, it must be supplied regularly.

Functions

Energy Production

Nicotinamide functions in the body as a component of the coenzymes NAD (nicotinamide adenine dinucleotide) and NADH (nicotinamide adenine dinucleotide phosphate). NAD and NADH accept and release hydrogen atoms derived from carbohydrates, protein and fat, in the energy production pathway (oxidative phosphorylation), to facilitate the production of ATP energy.

Synthesis of fatty acids and cholesterol

NADH is necessary in the synthesis of fat from acetylcoenzyme A (Acetyl CoA), which commonly occurs in the liver after over-ingestion of carbohydrates (many excess carbohydrate molecules are converted to Acetyl CoA in the liver).

Glycogen synthesis

NAD is required to store carbohydrates as glycogen in the liver and skeletal muscles.

Recommended Daily Allowance (Vitamin B3)

Classical Niacin Deficiency

Pellagra

Dietary levels of less than 7.5 mg per day of niacin, or niacin-equivalents from tryptophan, have been associated with the production of pellagra. Pellagra manifests as Dermatitis, Dementia, Diarrhea (the 3 Ds of pellagra) as well as tremors, sore tongue (beef tongue), and inflamed mouth. Other signs and symptoms include cracked, pigmented scaly dermatitis in body parts exposed to sunlight, anxiety, depression, and dementia.¹

Niacin Supplementation

1. Lowering Blood Lipids
   >Studies have shown that Niacin supplementation at 1,500-4,500 mg per day can reduce LDL-cholesterol by up to 23%, increase HDL-cholesterol by up to 33% and reduce LP(a) lipoprotein by up to 35%. However, high doses of Niacin in various forms can damage the liver. Thus, only practitioners who can monitor liver enzyme and function tests should recommend or prescribe Niacin for hyperlipidemic patients.² Some studies indicate that the safest of this form of Niacin is inositol hexaniacinate.³ However, the amount of research studying the safety of this form of Niacin remains quite limited. Risk of liver damage begins with intakes of Niacin at or above 1,000 mg per day.⁴
2. Osteoarthritis
   Niacin supplementation has been shown to improve global arthritis symptoms by 29% vs placebo (10% worse). Parameters included joint flexibility, inflammation and decreased reliance upon other anti-inflammatory medications.⁵
3. Defends Skin Against UV-light Damage
   Experimental evidence demonstrates that Niacin supplementation reduces UV-light-induced damage to the DNA of skin cells and protects against photo-aging of the skin. Niacin increases cellular ATP energy required by skin cells to repair the free radical damage imposed by UV-light exposure and bolsters immune function of the skin under test conditions. As such, Niacin supplementation (50-100 mg per day), in conjunction with antioxidant supplementation (Vitamins C, E, Selenium, Beta-Carotene) is emerging as a factor that may help to reduce risk of skin cancer and premature aging of the skin. ^{6,7,8,11,12,13}

Niacin Toxicity

A high dose of niacin, above 1,200 mg per day, which has been used to treat high cholesterol, increases the risk of liver damage. If continued long enough, it may aggravate diabetes by affecting glucose metabolism and can activate ulcers.⁹

Doses in excess of 50 mg of Niacin (nicotinic acid) but not nicotinamide, typically produce a transient flushing of the skin, due to its vasodilatory effects.¹⁰

Niacin supplemented at 100-1,000 mg without concurrent supplementation of folic acid and VitaminB12, can result in an elevation of homocysteine (17%), which may increase risk of heart disease.¹¹

Contraindications

Diabetes: Niacin dosage should not exceed 100 mg, per day.

Pre-existing Liver Disease: Niacin dosage should not exceed 100 mg, per day

.

Gout: Niacin dosage should not exceed 50 mg, per day. Nicotinic acid competes with uric acid for excretion in the urine. As such, high intakes of nicotimic acid can impair the excretion of uric acid, aggravating symptoms of gouty arthritis.

Peptic Ulcers: Niacin dosage should not exceed 50 mg, per day.^10,11,12

Safe Intake Level for Nutritional Support: 20-100 mg per day of Niacin is considered a safe level of supplementation for individuals 11 years of age and older, unless contraindications are present.¹³

Drug-Nutrient Interactions

The following drugs are reported to cause Niacin depletion:

Antibiotics

Antibiotics reduce B-Vitamin synthesis by destroying gut bacteria, which synthesize some B-Vitamins.^14,15

Oral Contraceptives and Hormone Replacement Therapy

Estrogen-containing drugs interrupt the conversion of tryptophan to niacin. In poorly nourished women signs of pellagra have been known to occur for this reason.^16,17

Isoniazid

This medication indirectly decreases the amount of Niacin in the body and may, therefore, increase Niacin requirement.¹⁸

Anticonvulsants

Niacin inhibits the breakdown of certain anticonvulsants, namely primidone and carbamazepine, which could alter the dosing requirement for these medications. Beware any signs of drug toxicity if combined with Niacin supplementation.¹⁹

Standard Textbooks of Nutritional Science:

- Shils M, Shike M, Olson J and Ross C. Modern Nutrition in Health and Disease. 9^th ed. Baltimore, MD: Lippincott Williams & Wilkins; 1993.

- Escott-Stump S and Mahan LK, editors. Food, Nutrition and Diet Therapy. 10^th ed. Philadelphia, PA: W.B. Saunders Company; 2000.

Bowman B and Russell RM, editors. Present Knowledge in Nutrition, 8^th ed. Washington, DC:.ILSI Press; 2001.

- Kreutler PA and Czajka-Narins DM, editors. Nutrition in Perspective. 2^nd ed. Upper Saddle River, NJ: Prentice Hall Inc.; 1987.

Illingworth DR, Stein EA, Mitchel YB, Dujovne CA, Frost PH, Knopp RH, et al. Comparative effects of lovastatin and Niacin in primary hypercholesterolemia. Arch Intern Med 1994;154:1586-95.

El-Enein AMA, Hafez YS, Salem H, Abdel M. The role of Nicotinic Acid and inositol hexaniacinate as anticholesterolemic and antilipidemic agents. Nutr Rep Intl 1983;28:899-911.

McKenney JM, Proctor JD, Harris S, Chinchili VM. A comparison of the efficiency and toxic effects of sustained vs immediate-release Niacin in hypercholesterolemic patients. JAMA 1994;271:672-7.

Jonas WB. The effect of Niacinamide on osteoarthritis: a pilot study. Inflamm Research 1996;45(7):330-4.

Gensler HL, Williams T, Huang AC, Jacobson EL. Oral niacin prevents photocarcinogenesis and photoimmunosuppression in mice. Nutr Cancer 1999;34(1):36-41.

Boelsma E, Hendricks HFJ, Roza L. Nutritional skin care; health effects of micronutrients and fatty acids. Am J Clin Nutr 2001 ;73(5):853-64.

Eberlein-Konig B, Placzek M, Przybilla B. Protective effect against sunburn of combined systemic Abscorbic Acid (Vitamin C) and d-alpha-tocopherol (Vitamin E). J Am Acad Dermatol 1998;38(1):45-8.

Kreutler P, Czajka-Narins D. Nutrition in Perspective. 2^nd ed. Englewood Cliffs, NJ: Prentice Hall; 1987.

Murray, M. Encyclopedia of Nutritional Supplements. Rocklin, CA: Prima Publishing; 1996.

Garg R, Malinow M, Pettinger M. Niacin treatment increases plasma homocysteine levels. Am Heart J 1999;138(6):1082-7.

Gersha SL, et al. Pharmacological effects of Niacotinic acid on human metabolism. J Lab Clin Med 1974;84:179-86.

Hendler S. The Doctors Vitamin and Mineral Encyclopedia. New York, NY: Simon and Schuster; 1990.

Cummings JH, Macfarlanw GT. Role of intestinal bacteria in nutrient metabolism. J Parenter Enteral Nutr. 1997;21(6):357-65.

Deguchi Y, Morishita T, Mutai M. Comparative studies on synthesis of water-soluble vitamins among species of bifidobacteria. Agric Biol Chem 1985;49(1):13-9

Bender DA, Totoe L. Inhibition of tryptophan metabolism by oestrogens in the rat: a factor in the etiology of pellagra. Br J Nutr 1984;51(2):219-24.

Shibata K, et al. Effects of sex hormones on the metabolism of tryptophan to Niacin and to serotonin in male rats. Biosci Biotechnol Biochem 1997;67(7):1200-2.

Matsui MS, Rozovski SJ. Drug-nutrient interaction. Clin Ther 1982;4(6):423-40.

Bourgeois BF, Dodson WE, Ferrendelli JA. Interactions between primidone, carbamazepine, and nicotinamide. Neurology. 1982;32(10):1122-6.