High Density Lipoprotein, or HDL, is a protective form of cholesterol. The National Institutes of Health (NIH) 2004 guidelines for cholesterol recommend a level of at least 40 mg/dL for men and 50 mg/dL for women. Some people find it easier to maintain this concentration of HDL than others. Genetic factors, as well as food choices, alcohol consumption and exercise all work together to create a healthy HDL level.
Causes of High-Normal HDL
After researchers discovered that HDL levels up to 82 mg/dL are related to a low risk of cardiovascular disease, the NIH panel published a list of causes for HDL elevation. They include genetic factors, a diet that is lower than 60 percent carbohydrates with sources of omega-3 fatty acids, a body mass index of less than 25, and exercise. In addition to these factors, a study reported in the May 1996 issue of the "British Medical Journal," reported that consuming 1 oz. of alcohol raises HDL by 4 mg/dL.
Weight loss can also produce profound elevations in HDL. In her "Lipids on Line" presentation, Baylor College of Medicine's Dr. Maria Denke reports that for every 7 lbs. of weight loss, HDL levels increased 1 mg/dL when weight reduction was maintained for six weeks. The difficulty with this strategy is found in maintaining a weight reduction diet long enough to effect and maintain the needed level of HDL elevation.
Using exercise as a way to raise HDL requires a similar level of sustained commitment. In the 1995 edition of "Circulation" a team under Dr. EC King reported a three to nine percent increase in HDL after two years of intense, aerobic activity consisting of 30-minute sessions, five days a week.
Causes of Extreme HDL Elevation
Levels of HDL above 82 mg per deciliter are called hyperalphalipoproteinemia, or HALP. This condition is dangerous because it leads to arteriosclerosis. At these higher levels, HDL reverses its transport function, bringing fats from the liver and redepositing them in the arteries.
The causes of HALP are divided into familial genetic patterns and secondary, acquired factors. The Merck Manual lists chronic alcohol abuse; hyperthyroidism; and the use of the corticosteroids, dilantin and estrogen without balancing progestin as causes of HALP, which are unrelated to the genetic patterns. In addition, medications used to treat low cholesterol, niacin, fibrates and statins can go beyond their intended function and lead to HALP. For that reason, HDL testing before and during treatment is recommended by the NIH guidelines.
Pregnancy as a Temporary Cause of High HDL
The number of pregnancies a woman experiences in her lifetime is directly related to her chance of developing cardiovascular disease. According to a 1987 study in the "American Journal of Epidemiology," pregnancy firsts elevates HDL from an average of 55 mg/dL in women of the same age to 66 mg/dL after a pregnancy of at least 28 weeks duration. Then, within one year of delivery the HDL levels falls below the woman's prepregnancy level especially if she also takes oral contraceptives.
References
- "National Institutes of Health Guidelines"; Third Report of the Expert Panel on Detection,Evaluation and Treatment of High Blood Cholesterol; September 2002
- "British Medical Journal"; Moderate alcohol intake and lower risk of coronary heart disease: meta-analysis of effects on lipids and haemostaticfactors; EB Rimm ,P Williams , et al; Decemeber 1999
- Baylor College of Medicine,"Lipids on Line" : Effects of Diet and Life Style Modification on HDL-C"; 2004
- "Circulation"; Long-term effects of varying intensities and formats of physical activity on participation rates, fitness, and lipoproteins in men and women aged 50 to 65 years; AC King, et al; 1995
- "Merck Manual"; Dyslipidemia, Lipid Disorders; AC Goldberg; September 2008
