Black Africa are among the populations where the risk of osteoporosis is one of the lowest in the world. Until now, scientists attributed this to three main factors: a high life expectancy of less -the pathological bone loss often intervening to 65 years-a more active lifestyle -how walk muscles protects its os- and lower diagnosis rates -this is not that these people suffer less from osteoporosis, but they do not have enough doctors to detect.
A study by Constance Hilliard, historian from the University of North Texas, supports an alternative hypothesis: many Africans and people of African descent are genetically adapted to a diet low in calcium, via intolerance lactose.
“Osteoporosis has noticeably appeared in the human genome here about 10,000 years, with the development of dairy farming,”says Hillard. “In a genetic compromise, those humans who had obtained the evolutionary advantages with increase of food resources through protein milk products may have adapted their own calcium homeostasis in a manner disadvantageous to their bone density. “
In fact, the data analyzed by Hilliard show that in infested West African region by the tsetse fly, which makes it almost impossible dairy farming, women have a fragility fracture rates (caused by osteoporosis) significantly lower than their East African counterparts. And if the women of West Africa are, in Hilliard, “virtually immune” against osteoporosis remains that fragility fractures in women of East Africa are also much less frequent than in women other countries, including Western.
The influence of lifestyle
Their common? They are mostly of Niger-kordofanienne ancestry, ethnic basin that has the particularity of being devoid of allele allowing the metabolize lactose food agency. In compensation, their bones retain calcium much better than those of European descent, where this allele is present in 85% of individuals.
Asked by Mother Jones, Connie Weaver, a nutrition researcher at Purdue University and a specialist in osteoporosis, Judge article by historian “very interesting . We know that genetics determines between 60 and 80% of bone density and that lifestyle does the rest. This article highlights a genetic difference that is probably more decisive on bone mass as diet or other cultural elements. “
According to Hillard, physicians should “pay more attention to the distant heredity individuals because the races are far more diverse than the few categories in which it was used to store them.”
Science is now working on a type of cancer particularly common and lethal prostate cancer in men of African descent and could face the same phenomenon. “The literature shows a strong correlation between prostate cancer and high consumption of dairy products, except that African Americans are affected by this cancer and consume relatively little dairy, “she says.