October 09, 2006
High Omega 6 Fat Diet Plus Gene Variant Bad For Blood Lipids

Whether it is safe or harmful to pig out on large amounts of french fries cooked in corn oil may depend on which genetic variation of apolipoprotein A5 (APOA5) that you carry. People who carry the wrong APOA5 version and eat more than 6% of their calories from omega 6 fatty acids get high triglycerides and other bad blood lipid components.

Boston -- Researchers from the Jean Mayer USDA Human Nutrition Research Center (USDA HNRCA) at Tufts University and colleagues have found another link among genes, heart disease and diet. The study, published in Circulation, examined apolipoprotein A5 (APOA5), a gene that codes for a protein, which in turn plays a role in the metabolism of fats in the blood. The results show that people who carry a particular variant of APOA5 may have elevated risk factors that are associated with heart disease, but only if they also consumed high amounts of omega-6 fatty acids in their diets.

Corresponding author Chao-Qiang Lai, PhD, a USDA-Agricultural Research Service (ARS) scientist at the USDA HNRCA, and colleagues analyzed lipid levels and dietary assessment questionnaires of more than 2,000 participants in the Framingham Heart Study and quantified their intake of different types of fats.

Omega-6 fatty acids, as well as omega-3 fatty acids, are polyunsaturated fatty acids (PUFAs) and, according to a report from the National Institutes of Health Office of Dietary Supplements, most Americans consume about 10 times more omega-6s than omega-3s. Omega-3s are found in nuts, leafy green vegetables, fatty fish, and vegetable oils like canola and flaxseed, while omega-6s are found in grains, meats, vegetable oils like corn and soy, and also processed foods made with these oils. Both omega-3s and omega-6s, known as essential fatty acids, must be consumed in the diet because they are not made by the body.

"We know that some people are genetically predisposed to risk factors for heart disease, such as elevated low-density lipoprotein levels in the blood," says Lai, "and that APOA5 has an important role in lipoprotein metabolism. We wanted to determine if certain dietary factors change the role of APOA5 in metabolizing these lipoproteins and their components, such as triglycerides."

Lai and colleagues found that approximately 13 percent of both men and women in the study were carriers of the gene variant. Those individuals that consumed more than six percent of daily calories from omega-6 fatty acids displayed a blood lipid profile more prone to atherosclerosis (hardening of the arteries) and heart disease, including higher triglyceride levels.

The ability to get the DNA sequence of all your genome is starting to become useful. The information is starting to become practically useful for individuals and not just useful for scientists. DNA sequencing still costs orders of magnitude too much money. But the cost of getting a small subset of genes checked for problematic genetic sequences is much more affordable.

Share |      Randall Parker, 2006 October 09 10:58 PM  Aging Genetics

John said at October 10, 2006 5:58 AM:

The latest research says that The Mediterranean diet is very good in preventing and reducing the risk of Alzheimer's disease. Here is the reference: http://www.emaxhealth.com/91/7805.html

James Bowery said at October 10, 2006 10:12 AM:

Mediterranean diet may be good for Mediterraneans but the other 75% of the population has difficulty metabolizing starch properly. Something similar may be going on with Omega-6 fats.

But I'm not going to hold my breath waiting for the ethnic correlations with APOA5 polymorphisms.

The thing to keep in mind is that things that affect cardiovascular health also affect the rate of brain aging. The "good" news about that is about the time your brain starts to go due to reduced perfusion from clogged capillaries, your heart gives out so you die a mercifully swift death before your brain function is gone. The better news is that you may be able to live a long vigorous life, mentally and physically, by keeping your bad triglycerides down.

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