Saturday, September 10, 2016

Why Some Populations May Be Genetically Immune to Osteoporosis

As an evolutionary historian, I have devoted the last several years to researching the health implications of genetic diversity. I was particularly concerned with the tendency of medical researchers to unwittingly use the biology of people with Northern European ancestry as a universal standard for everyone. For instance, lactose intolerance may be a disorder in that community, which suffers high rates of osteoporosis. But since 65% of the world’s population are lactose intolerant and have low rates of osteoporosis, a one-size-fits-all approach to bone health can prove dangerous for those whose ethnic-specific biological needs are overlooked.

In June of 2016, I published an article in NATURE: BoneKEy, showing that osteoporosis is not a global problem. It has a strong and devastating impact in dairy-farming societies and is virtually non-existent in the tsetse zone of West Africa, where cattle rearing and dairying are not possible. Previous studies have tried to correlate the degenerative bone disease with socio-economic income. However, this study compares two regions of Africa with similar socio-economic conditions. In dairy-farming East Africa, the incidence of osteoporosis is 245 per 100,000. However in the tsetse belt of West Africa, where people do not consume dairy products, it is 3 per 100,000. When regression analyses are performed on 40 countries around the world, the association between dairy consumption and osteoporosis is high (0.851). It only correlates with national Gross National Product at a regression rate of 0.447.


In nature, we sometimes find powerful examples of genetic trade-offs. The genetic mutations that allow for dairy-farming populations to digest the lactose in milk have over time reduced the body’s ability to absorb sufficient calcium to maintain strong bones. This does not mean that milk or dairy should be shunned by everyone. But what it does mean is that medical researchers need to recognize the fact that ethnic groups who maintain strong bones but consume little dairy (on account of lactose intolerance) do not need the same level of dietary calcium as lactose tolerant populations.

The consumption of more dietary calcium than our bodies require may have severe implications. [My current not yet published research shows a strong link between calcium consumption and two forms of cancer with high mortality rates. African-Americans come from low calcium ancestral environments. In the high-calcium, dairy food culture of the U.S., their fatality rates are more than two times higher from advanced prostate cancer in males and triple negative breast cancer in females].

My research also shows that osteoporosis entered the human genome with the introduction of dairy farming. For this reason, it is vital that  medical researchers begin to look at the effects of feeding dairy products to lactose intolerant ethnic populations from Africa, Asia and Latin America. We should no longer assume that “milk builds strong bodies for everyone”.

Our federal nutritional guidelines also need to take into account the fact that different ethnic populations may metabolize minerals such as calcium and sodium differently. The standards that work for people of Northern European ancestry, may in some cases, be disastrous for the many ethnic populations from other parts of the world. The reason for this is because or human biology is exquisitely attuned to the geological and food environment of our ancestral homelands. We must honor those differences.


Citation:

 Hilliard C. High osteoporosis risk among East Africans linked to lactase persistence genotype NATURE: BoneKEy  Reports(2016)5,Article number:803(2016) doi:10.1038/bonekey.2016.30  Published online: 29 June 2016
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