When you eat a meal, glucose levels in your blood increase. This stimulates the pancreas to a release a hormone called insulin. Insulin then helps glucose to transit from blood into the cells. Inside of the cells, glucose is used for generation of energy. Under certain circumstances, your cells may become less responsive to insulin. For example, this happens with your muscle cells when you do not exercise. Glucose then cannot efficiently flow from blood into the cells despite that the blood levels are high. This condition is called "insulin resistance." The elevated blood glucose increases levels of lipids, which in turn elevates your risk for developing a cardiovascular disease. Niacin is a vitamin B-3 that belongs to lipid lowering drugs. Niacin alters lipid profiles in a unique way.
Insulin Resistance
When your cells cannot obtain glucose, you feel constantly tired. The glucose levels in your blood are tested most commonly after fasting over night. When you are healthy, your blood glucose concentration is less than 100 mg per dL. If your levels are between 100 and 125 mg glucose per dL, you have impaired glucose tolerance due to insulin resistance.
Lipid Profile
The laboratory tests for evaluating this condition include fasting levels of triglycerides, total cholesterol, low-density lipoprotein or LDL, and high-density lipoprotein or HDL. Triglyceride levels should be lower than 150 mg per dL of blood. LDL is particles that deliver cholesterol and triglycerides to your body cells, and it is sometimes referred to as the bad cholesterol. The levels of LDL should be less than 70 mg per dL of blood. In contrary, HDL are particles that deliver abundant cholesterol from your body back to the liver and are referred to as the good cholesterol. The content of lipids in these particles is smaller than in LDL. Instead, HDL contain higher amount of protein, which makes their density higher, hence the name. The levels of HDL should be greater than 40 mg per dL in men and 50 mg per dL in women. The ratio of LDL to HDL in a healthy person is less than 3.5.
The Effect of Niacin on Lipid Profile
Helen Vosper summarized the role of niacin in the therapy of disturbed lipid profiles in the September 2009 issue of "British Journal of Pharmacology." Together with other lipid lowering drugs, niacin reduces blood levels of LDL and triglycerides in blood. In addition, niacin has a unique characteristic that other drugs lack. It is the most effective agent that increases the blood levels of HDL, or the good cholesterol. Side effects, such as hot flushes, may be the reason why you may not like to take this drug. Vosper reports that niacin-induced effects on lipids and hot flushes involve different pathways and that compounds affecting lipid profiles without side effects are currently under development.
Sources of Niacin
The recommended dose of niacin for hyperlipidemia are 1 to 2 g orally in tablets each day. For a healthy adult, the daily recommended doses are 35 mg per day, as reported by United States Department of Agriculture. Niacin is found in food, including beef liver, chicken breast, eggs, legumes, cereals or peanuts.
References
- "Physiological Basis of Medical Practice"; John B West MD, PhD, DSc; 1990
- "Diabetes Care"; American Diabetes Association. Standards of Medical Care in Diabetes---2011; January 2011
- Medscape; Metabolic Syndrome; Stanley S. Wang et al.; September 2010
- "British Journal of Pharmacology"; Niacin: A Re-emerging Pharmaceutical for the Treatment of Dyslipidaemia; Vosper Helen; September 2009.
- Medscape Reference: Niacin
- Unites States Department of Agriculture National Agricultural Library: Dietary Guidance
