Racial and ethnic minorities experience death at a younger age and illness more frequently across a broad range of chronic conditions. These include high blood pressure, heart disease, diabetes, obesity, asthma, just to name a few.
According to the Centers for Disease and Prevention (CDC) racism has caused a pronounced negative impact on the health of minorities and communities of color. Many sociologists and public health experts blame racism and the resulting so-called social determinants of health for lower health status among black Americans. The social determinants of health are a big area of research nowadays. For example, to what degree does being born into poverty affect your health in later years? What effect does racism and micro-aggressions do to your mental health? These are all questions epidemiologists would like to answer. However, Texas Monthly wrote about another explanation for racial disparities:
But Hilliard writes… “current medical research simply overlooks the unique ecological conditions of American Blacks’ genetic ancestry.” Focusing instead on social factors that may have an impact on heath, “millions of dollars are allocated to studies that continue to attribute this population’s salt-sensitive hypertension and kidney failure solely to stress resulting from racism,” she writes.
Some of the chronic conditions experienced by racial minorities are routed evolutionary factors in their distant past long before their forebearers came to America. That is the premise of a new book Ancestral Genomics: African American Health in the Age of Precision Medicine by Constance Hilliard, Professor of History at the University of North Texas.
Our genetic history can affect our health. The simplest proof is lactose intolerance. By some estimates nearly three-fourths of the World population stops producing lactase after weaning and are lactose intolerant. Lactose intolerance is not random, occurring arbitrarily to some people and not others. It is regional. Most Asians are lactose intolerant, as are most of Africans. The Northern Hemisphere has a very low rate of lactose intolerance, while the Southern Hemisphere has a very high rate. If you go back centuries, you will also find a relationship between dairy animal husbandry, turning milk protein into cheese products and populations that can digest milk all their lives. Making cheese was a way of preserving milk protein and cows were a way of converting grass into protein. Evolution favored those who could digest milk in areas where cows could thrive.
As she dug further into the ecological conditions unique to interior West Africa, Hilliard came to her next big revelation—this one involving dairy products. In parts of West and Central Africa’s “tsetse belt” today, 99 percent of the inhabitants are lactose intolerant. The tsetse fly endemic to the region carries a pathogen that causes a wasting disease in cattle. Until recently, it was virtually impossible to maintain a healthy herd of cattle there.
It doesn’t stop with milk. Salt is another interesting anecdote. Throughout history the African interior had little salt. There was literally a thriving trade where those in the middle of the continent traded gold for salt. Over eons of time people in the heart of Africa evolved to survive on diets mostly devoid of salt. The high sodium levels in Western diets wreak havoc on their blood pressure today due to evolutionary biology that makes many African Americans highly sensitive to sodium.
Hilliard argues that the elevated creatinine levels found in many African Americans may be an indication of kidneys that evolved to survive in a salt-poor ecological region. An African American whose ancestors hail from, say, coastal Nigeria likely wouldn’t have the same creatinine levels. Hilliard references studies that have consistently found salt sensitivities in African Americans, which—when paired with the salt-heavy contemporary American diet—have led to higher blood pressure and increased rates of heart disease and kidney failure.
Basically, not all Americans’ bodies are alike. We are a nation of immigrants, whose ancestors came from diverse parts of the World. Those differences could mean a lot in terms of genetic makeup, which in turn could affect Americans’ health in various ways.
From this information, Hilliard concluded that severe health disparities among racial groups in America may be explained, in large part, by inexact dietary guidelines for salt and dairy products. Rather than dividing patients into groups based on race, Hilliard writes that we should focus instead on what she calls ecological niche populations. Patients whose ancestors evolved in the same area will likely have similar genetic profiles and similar dietary needs and sensitivities.
It’s an interesting take on racial disparities and an area of research that deserves more attention. The article in Texas Monthly provides a glimpse of Hilliard’s research and her new book Ancestral Genomics: African American Health in the Age of Precision Medicine looks interesting.
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