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Obesity gene triggered by saturated fat discovered

Kathleen Blanchard's picture

Researchers from Tufts University have discovered an obesity gene, triggered by saturated fat. The gene was found to promote increased body mass index (BMI) and obesity in three population studies among men and women who possess the CC genotype – but only in individuals who consume a diet high in saturated fat.

The scientists found an association between how genes behave and food. The findings, according to the authors, mean that diets could be individually tailored to lower rates of obesity and chronic disease, using an approach called nutrigenomics. The essence of nutrigenomics is that diet influences health depending on one’s genetic makeup. In the current study the apolipoprotein A-II gene (APOA2) promoter, a piece of DNA that controls expression of the APOA2 gene was found to be linked to obesity in individuals who possess the CC genotype (a variant of the APOA2 promoter). There are two APOA2 variants that exist – T and C; broken down into three genotypes CC, TT, and TC.

Study participants were divided to receive either a low or high saturated fat diet, and included 3,462 men and women taking part in the Framingham Offspring Study (FOS), the Genetics of Lipid Lowering Drugs and Diet Network Study (GOLDN) and the Boston-Puerto Rican Centers on Population and Health Disparities Study (Boston-Puerto Rican Study). The groups were separated by CC, TT, and TC genotypes, looking at saturated fat intake, obesity risk and BMI.

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First author Dolores Corella, PhD, professor at the Valencia University-CIBER Fisiopatología de la Obesidad y Nutrición (Spain), and visiting scientist in the Nutrition and Genomics Laboratory at the USDA HNRCA says, "Across all three studies, the CC carriers who consumed high-saturated fat diets had the highest BMIs compared to the TT and TC genotypes and, most notably, other CC carriers who reported consuming low-saturated fat diets. This work is based on a two year-old study finding genotypes influence food preferences, calorie intake and BMI."

A high saturated fat diet was set at more than 22 grams or more per day. Individuals who carried the CC gene were most susceptible to higher BMI and obesity.

According to corresponding and senior author Jose Ordovas, PhD, director of the Nutrition and Genomics Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts. "Our findings strengthen support for the science of nutrigenomics and are another step toward the goal of individually tailoring dietary recommendations to lower risk of chronic disease or conditions like obesity."

The researchers say there is a need to understand more about how genes interact with diet and can lead to obesity. Ten to fifteen percent of the US population carries the CC gene that is now linked to obesity among individuals who consume high saturated fat diets.

Arch Intern Med. 2009;169(20):1897-1906