|A compound found in oil-rich fish such as salmon, has been shown to reshape the blood lipid profiles.|
Research chemist Darshan Kelley of the ARS Western
Human Nutrition Research Center in Davis, Californias, and federal and
university co-investigators conducted the study of DHA, or docosahexaenoic
acid, a polyunsaturated fatty acid thought to improve cardiovascular health.
The research, reported previously in the American Journal of Clinical
Nutrition, is likely the first to analyze-in high-triglyceride males-DHA's
effects on both fasting and post-meal triglycerides, and on quantities and sizes
of HDL, LDL and VLDL cholesterol particles. High triglycerides, high
cholesterol and a high number of small particles of LDL cholesterol in the
blood increase risk of cardiovascular disease, the nation's leading cause of
death, according to Kelley.
Probing DHA in humans
The study is also one of only about a dozen, in humans, to probe the effects of
DHA alone, rather than in tandem with another natural oil, EPA, or
eicosapentanoic acid. EPA occurs with DHA in fish oil.
Half of the study's 34 volunteers, age 39 to 66, consumed about one-half
teaspoon of DHA daily, in addition to regular meals, for 90 days. The other
half received olive oil in place of DHA oil.
Blood samples taken after fasting, and within eight hours after meals, showed
that DHA reduced by 22 percent the number of small LDL (low-density
lipoprotein) particles. LDL's small particles are the size most harmful to the
cardiovascular system. DHA increased the number of large LDL particles by 127
percent. Since large LDL particles are less harmful than small ones, some
researchers believe large LDL particles do not harm the arteries.
DHA also lowered triglycerides by 24 percent in both the fasting and post-meal
samples. The after-meal effect, shown in only a few other studies, may be of
particular interest to medical professionals looking for alternatives to
conventional triglyceride-lowering therapies, according to Kelley.