The Grapevine

Black American Men With This West African Genetic Variant May Have Partial Immunity To Obesity

black man
Some black men in America may have luckily inherited a genetic resistance to obesity from their West African ancestors. Pixabay, Public Domain

Race matters a great deal when it comes to your obesity risk. An alarming 56 percent of black American women over the age of 20 are obese, compared to only 36 percent of white women. On the other hand, despite having similar diets and exercise regimes as their female counterparts, black men are no more likely to be obese than white men. A new study may have an explanation for this medical paradox. According to the research, certain gene variants that originated in West Africa may offer some black males partial protection against obesity by making those lucky enough to inherit it less likely to collect fat in the mid-waist and trunk.

Our genes predict many things about our health and mental aptitude, from our likeliness of developing certain health conditions, such as MS, to our ability to learn a foreign language. The risk factor for obesity is also believed to be partially influenced by our genetic makeup, and much research has gone into finding the elusive “fat gene.” However, what most interested researchers from the University of Alabama at Birmingham and the University of Arizona was not why black American women were getting so fat, but rather why black men were not despite living in the same environments and presumingly having the same genetics.

The team analyzed genetic data from 4,425 healthy black men and women between the ages of 45 and 85. This data originated from two cohort studies sponsored by the National Heart and Lung Blood Institute of the National Institutes of Health. Results of the study found that black men with larger amounts of West African ancestry in their DNA were significantly less likely to be obese. Study author Dr. Yann Klimentidis told Medical Daily this suggests that either these West African genes may offer protection against obesity, or that addition of specific genetic variants inherited from European ancestors may increase obesity in black American men.

What makes the black American genome so fascinating is its large amount of genetic diversity due to centuries of racial mixing, or admixture, mostly with European and Native American people. According to the History Channel, the first Africans arrived in British North America, what is now the United States, in 1619 when a Dutch ship brought 20 African slaves to what was then the British colony of Jamestown, Virginia. Although most black Americans today can claim ancestry to the estimated six to seven million West African slaves who were brought to the U.S. during the 17th and 18th centuries, a recent study found that the average black American’s genes are around 16 percent European and at least 1 percent Native American. This percentage of racial admixture varies greatly depending on where in the U.S. For example, black Americans living in the Southwest and Northeast generally have higher amounts of European ancestry than those who live in the American South.

It has not been clear whether having more or less African ancestry has changed the actual health of black Americans, but the recent study says it may make a difference. According to the research, Black American men with more West African genes have a relatively lower risk of being overweight, obese, and diabetic, and tended to have a lower waist circumference and waist-to-hip ratio. The reason for this may be due to a genetic variant which originated from West Africa and may control how males distribute their weight, although a specific gene variant has not yet been identified.

These findings are not only interesting but could also be applied clinically in gene identification. According to lead researcher Dr. David Allison, understanding the ways gene variants protect against obesity could be highly useful in research into obesity prevention and treatment. Still, this is only one part of the bigger picture.

“Although genetics factors are important, I think that it is probably more important at this point to identify the non-genetic factors that increase the risk of obesity in African-American women, and try to address those,” concluded Klimentidis

Source: Klimentidis YC, Arora A, Zhou J, Kittles R, Allison DB. The Genetic Contribution of West-African Ancestry to Protection against Central Obesity in African-American Men but Not Women: Results from the ARIC and MESA Studies. Frontiers in Genetics . 2016

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