Standard recommendation on calcium intake may trigger certain cancers in African Americans, evolutionary historian says

Thursday, May 31, 2018 - 13:09

DENTON (UNT), Texas -- The Health and Medicine Division of the National Academy of Sciences has long recommended that adults consume at least 1,000 milligrams of calcium daily, and women age 50 and older should consume even more.
What’s great advice for Americans with European ethnicity, however, may not be great advice for Americans with West African ancestry. That demographic has high susceptibility to certain cancers when exposed to America’s calcium-rich, dairy food culture, according to Constance Hilliard, University of North Texas researcher in evolutionary African history.
Hilliard’s research supports the idea that the nation and region of origin of ancestors contributes to the risk of developing, or not developing, specific medical conditions. She has created an ecological model that looks at certain racial healthcare disparities that result from ethnic-specific genetic variants in individuals. These variants, Hilliard says, evolved from ecological conditions in the person’s ancestral nation of origin.
Hilliard has examined rates of metastatic, or fast-growing, prostate, breast, colorectal and ovarian cancers in African Americans, and presented results of her study on high prostate cancer rates at the American Association for Cancer Research annual conference on April 16.
While research shows that over-consumption of calcium is a trigger for metastatic prostate cancer, Hilliard says, African American males are four times more likely to die of this cancer than Caucasian males, despite the fact that African Americans consume far less dairy than Caucasians and are considered calcium deficient by federal nutritional standards. 
“The ecological model system reveals that 81 percent of black males diagnosed with metastatic prostate cancer consume 900 milligrams or less of calcium per day, compared to 41 percent of white Americans,” she says. 
The difference can be explained by African Americans carrying the TRPV6a gene variant, which is correlated with unusually high calcium absorptive capacity — so 800 milligrams is considered over-consumption of calcium for these men, whose ancestors in West Africa consumed no more than 200 milligrams a day, Hilliard says.
“Tsetse flies in West Africa attack cattle and so prevent dairy farming, which lead to diets low in calcium. In addition, the TRPV6a gene variant leads to lactose intolerance,” she says.
The same gene variant that may trigger high rates of aggressive prostate and other cancers in African Americans also made West African women “essentially immune” to osteoporosis, says Hilliard, who discovered in previous research that women from 40 African nations had much lower rates of hip fractures associated with osteoporosis than U.S. women. That research was published in 2016 in the Bonekey edition of Nature.
“We need to understand what our vulnerabilities are in health based on our ancestral vulnerabilities,” Hilliard says. “We usually just get one message about calcium consumption as Americans, but one population can be harmed by more calcium, and less calcium won’t lead to osteoporosis for them.”

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