While the "bad" cholesterol carrier called low density lipoprotein or LDL delivers cholesterol into cells, the "good" cholesterol carrier called high density lipoprotein or HDL primarily removes cholesterol from cells, targeting it for elimination by the liver (Zhang). High levels of HDL are as important to good for cardiac health as low levels of LDL. When exercise and a healthy diet fail to maintain healthy levels of HDL, supplements of niacin are the most effective way to increase it.
Sources
Niacin, or nicotinic acid, is a water-soluble B vitamin. It occurs naturally in high levels in foods such as lean meat, poultry and fish, eggs, dairy products and nuts. Niacin supplements are available over the counter or in prescription strength. When taken as a supplement under the advice of a doctor, niacin can provide excellent cardiovascular benefits, and doctors commonly recommend niacin supplements to boost HDL. Despite the cardiovascular benefits of niacin, the Mayo Clinic cautions that patients should not use niacin without a doctor's advice because of potential side effects. Niacinamide and nicotinic acid both make up vitamin B3. However, niacinamide does not increase HDL levels.
Side Effects
In high doses, niacin can cause side effects including liver damage, elevated blood sugar levels, upset stomach, headache and dizziness. Niacin can also cause blood to rush to the skin's surface, causing flushing and a hot sensation. While harmless, flushing is bothersome to many people and can drive them to quit taking niacin supplements despite its beneficial effects on HDL levels and overall cardiovascular health.
Mechanism
Niacin may boost HDL levels either by increasing its production, or slowing its destruction. Scientists showed that niacin has no effect on the production of HDL, suggesting that it must slow destruction of HDL. In their 2008 paper in "Journal of Lipid Research," Dr. Zhang and colleagues showed that niacin inhibits the expression of a protein that triggers the liver to sequester and degrade HDL. With HDL's destruction slowed by niacin supplementation, blood levels of "good" cholesterol increase. Niacinamide does not inhibit the destruction of HDL, explaining why it is not effective in treating high cholesterol.
Effectiveness
By itself, niacin can boost HDL levels by 15 to 35 percent. In addition, niacin decreases LDL by about 15 percent and also decreases triglyceride levels. When combined with a type of drug called statins, which inhibit the liver from making cholesterol, niacin can lower LDL by an additional 10 percent.
Benefits
When doctors measure total cholesterol, the figure includes HDL, LDL and triglyceride levels. Niacin not only increases HDL levels, it also directly acts to lower LDL levels and to decrease triglycerides, another component of total cholesterol. While niacin increases HDL levels, the effect of higher HDL is to actually lower total cholesterol levels.
References
- "Journal of Lipid Research"; Lin-Hua Zhang et al.; Niacin inhibits surface expression of ATP synthase beta chain in HepG2 cells: implications for raising HDL; March 2008.
- Mayo Clinic: Niacin
- Harvard Health: New lowdown on cholesterol
- Health Central: Niacin
- Mayo Clinic: Niacin (vitamin B3, nicotinic acid); Niacinamide
