by Leah Frankel, MS, RD
Hypercholesterolemia (high cholesterol) affects 37.7 million Americans and is a major cause of cardiovascular disease (American Heart Association, 2005). Numerous methods are used to lower cholesterol including change in diet, exercise or use of medications (usually a type of drug called a statin. You’ve seen them plaguing your primetime TV commercials). However, research suggests that a simple vitamin may actually help improve cholesterol levels.
Niacin, previously referred to as Vitamin B3, is important in the function of the digestive system, skin, nerves as well as metabolism. The RDI (Recommended Daily Intake) for niacin ranges from 14 mg/day (females 19-70) to 16 mg/day (males 19-70). Food sources of the B vitamin include: dairy, produce, fish, eggs, lean meats, nuts, legumes and enriched breads and cereals.
There are two forms of niacin: nicotinic acid and nicotinamide (no need to memorize these names…they will not be on the test at the end of the article). Both of these forms have the same function when taken in milligram doses. However, when nicotinic acid is taken in gram doses, it works as a cholesterol lowering drug. The effect of nicotinic acid as a cholesterol-lowering agent was first seen in the middle of the 20th century when Rudolf Altschul noticed that giving rabbits nicotinic acid caused their cholesterol levels to lower (1). At this time he also discovered that nicotinamide had no effect on lowering cholesterol.
So how does it work? At approximately the same time that nicotinic acid was discovered to lower cholesterol levels, free fatty acids were observed to be precursors of LDL (free fatty acids are converted into LDL and remember that LDL is the bad form of cholesterol. We outline the different types of cholesterol below). Nicotinic acid was found to lower concentrations of free fatty acids in a matter of minutes, with an increase in free fatty acid levels back to normal levels in approximately an hour. Studies done in rats explained this observation, because nicotinic acid was shown to prevent the release of free fatty acids that were stored as fat (2). Therefore, nicotinic acid is believed to lower cholesterol by preventing fat from being turned into LDL.
The two types of cholesterol we are most familiar with are HDL (high density lipoprotein) and LDL (low density lipoprotein); HDL is commonly known as the “good” cholesterol and LDL as “bad” cholesterol. LDLs are produced by the liver and carry cholesterol and other lipids (fats) from the liver to different areas of the body, like muscles, tissues, organs, and the heart. HDL is produced by the liver to carry cholesterol and other lipids (fats) from tissues and organs back to the liver for recycling or degradation. Once it was determined that high HDL levels would lower the incidence of cardiovascular disease the early findings that nicotinic acid would raise HDL became of some importance. Nicotinic acid has the unique property of modifying each type of cholesterol in a way that is beneficial in reducing the risks of vascular disease. It not only lowers LDL, it raises the concentration of HDL which is unique to nicotinic acid, and very effective in changing your cholesterol mix for the better.
Due to the role of nicotinic acid as an HDL-raising drug, it is now being considered as a complementary drug to be used with statins or other LDL lowering drugs. Nicotinic acid treatment was shown to increase HDL levels by 21% (3). In an earlier trial, when nicotinic acid was given with statins, it was seen that there was an increase in HDL by almost 30%, and a lowering of LDL cholesterol by 25-40%…pretty good if you ask us. Other studies using nicotinic acid in combination with statins have found that there is a significant clinical benefit because there is a reduction in both coronary artery disease events (i.e. heart attacks) and mortality (i.e. you die). This is thought to be due to the rise in HDL, which is only seen with nicotinic acid.
The biggest problem with the use of nicotinic acid in lowering cholesterol is the side effects. There are two major side effects seen in patients taking nicotinic acid:
Flushing (You feel warm and get red in the face. Imagine passing gas in the middle of a first date – that feeling)
Increased uric acid in the blood
A prolonged-release formula of nicotinic acid, also known as extended-release or ER, has been created to help minimize the side effects.
So should we be consuming greater amounts of niacin in our diet to help manage our cholesterol? The answer for now, is probably not. The tolerable upper limit (what is considered a “safe upper limit”) for niacin is 35 mg/day and as noted above niacin only has a lipid lowering effect when taken in gram doses (10-fold higher than what is safe today). While consuming extra niacin will probably not lead to healthier cholesterol levels in its current formulation the research between the effects of nicotinic acid and cholesterol levels are promising as pharmaceutical companies are currently creating new forms of nicotinic acid, which will hopefully have less side effects allowing for more extensive use.