Niacin is not a new member of the pharmacology landscape. Known as vitamin B3, it is one of the eight water-soluble vitamins in the vitamin B complex. The term niacin refers to both nicotinic acid and its amide derivative, nicotinamide (niacinamide).

Niacin is used as an antioxidant and in the treatment of nutritional deficiencies.1 While niacin is well known for preventing pellagra, it is only in the past 15 to 20 years that other medicinal uses for this common vitamin have emerged.


Background


Niacin has primarily been used to increase HDL cholesterol. HDL helps manage LDL cholesterol in the bloodstream, and this has significant long-term effects on the risk of cardiovascular disease (CVD). Studies show that a 2% to 3% increase in HDL corresponds to a 2% to 4% reduction in CVD occurrence.2

Science


Niacin is found in many foods, including yeast, meat, fish, milk, eggs, green vegetables, beans and cereal grains.3 Niacin is essential for the body to metabolize fats and sugars. The amino acid tryptophan, found in many proteins, is also partially converted into niacin in the body.3

While clinicians are probably most aware of niacin and its impact on serum lipid levels, the vitamin is also essential in generating energy. Niacin is converted into nicotinamide adenine dinucleotide, and is ultimately used in adenosine triphosphate and adenosine diphosphoribose transfer reactions.1 Niacin is also a mild anticoagulant. Researchers have found that niacin enhances fibrinolysis, especially in hyperlipidemic men.1

In addition to lowering total LDL numbers, niacin 
studies including the Familial Atherosclerosis Treatment Study (FATS) verified that the vitamin also changes the molecular size and density of LDL particles.4 Chemically, niacin increases the concentration of lighter, smaller LDL particles and decreases the production of the heavier, denser particles.4 Long-term studies examining the risk factors for CVD show that the atherogenicity of LDL particles is directly proportionate to the density of the dominant particles. 


In addition, niacin has been linked to the prevention of both cataracts and Alzheimer disease (AD). In the Blue Mountains Eye Study, researchers monitored nearly 3,000 pros­
pective food-and-supplement diaries in adults aged 49 to
 97 years.5 Various nutrients were tracked, as was the use of 
OTC multivitamins. Patients were examined at baseline and two years later for cataract development.

Niacin, in both food and supplement forms, was associated with a reduced occurrence of cataracts. The reduction was more significant when niacin was taken in conjunction with other vitamins and antioxidants, including vitamin A, thiamin and riboflavin.5

In another long-term dietary study, researchers examined more than 8,000 people older than age 65 years for the development of AD and related cognitive decline.6 In the first three years, niacin intake showed a linear correlation with a decrease in cognitive decline in the geriatric set.6

A subset of study participants who had undergone a cardiovascular event during the trial were placed on niacin and also assessed for cognitive decline. Findings showed a significant 44% reduction in cognitive impairment in patients reporting a median daily niacin intake of 22 mg in either food or supplement form.6

Safety, interactions


Niacin is generally considered safe when taken in regular amounts. Common dermatologic side effects of flushing and itching are usually self-limited. However, due to the vasodilatory effect, niacin may produce an excessive drop in BP when taken in conjunction with certain BP medications. Caution is urged when giving niacin to an individual with liver damage, since the vitamin competes for various hepatic metabolic pathways. 


Dosage and cost


As with all nutrients, the best way to get niacin is through food intake. Obviously, when using niacin as a therapeutic agent, larger doses are needed. Immediate, time-released and extended- release niacin are available OTC.7 The FDA has approved two name-brand formulations of niacin for lowering LDL levels.2 The main consideration with the OTC brands, especially immediate-release formulations, is the increased intensity of side effects.8

The cost of niacin fluctuates depending on the type of formulation and dose, but it generally costs approximately $30 for a one-month supply. Niacin is available as a tablet with varying rates of absorption; the range of a therapeutic daily dose is 1,000 mg-3,000 mg. Depending on the type of tablet used, this may be dispensed in single or in multiple doses.2

Summary


With the increasing emphasis placed on the burden of CVD, something as common as niacin should be a top-seller. Cheap, effective and affordable, niacin should be at the top of our lists when deciding on therapy for patients with hyperlipidemia and other cardiovascular risk factors.

Sherril Sego, FNP-C, DNP, is a staff clinician at the VA Hospital in Kansas City, Mo., where she practices adult medicine and women’s health. She also teaches at the nursing schools of the University of Missouri and the University of Kansas.

References


1. Niacin and niacinamide (vitamin B3) page. Natural Medicines Comprehensive Database website. 


2. Brown BG, Zhao XQ, Chait A, et al. Simvastatin and niacin, antioxidant vitamins, or the combination for the prevention of coronary disease. N Engl J Med. 2001;345:1583-1592.


3. Niacin and niacinamide (vitamin B3) page. Medline Plus website.

4. Zambon A, Hokanson JE, Brown BG et al. “Evidence for a new pathophysiological mechanism for 
coronary disease regression: hepatic lipase-mediated changes in LDL density.” Circulation. 1999;99:1959-1964.


5. Kuzniarz M, Mitchell P, Cumming RG et al. “Use of vitamin supplements and cataract: the Blue Mountains Eye Study.” Am J Ophthalmol. 2001;132:19-26.


6. Morris MC, Evans DA, Bienias JL et al. “Dietary niacin and the risk of incident Alzheimer’s disease and of cognitive decline.” J Neurol Neurosurg Psychiatry. 2004;75:1093-1099.


7. McKenney J. “New perspectives on the use of niacin in the treatment of lipid disorders.” Arch Intern Med. 2004;164:697-705.


8. Mills E, Prousky J, Raskin G et al. “The safety of 
over-the-counter niacin: A randomized placebo-controlled trial [ISRCTN18054903].” BMC Clin Pharmacol. 2003;13:3-4.