Monday, December 26, 2011

High Blood Pressure in African-Americans, Salt & Timbuktu

Slaves Marched Thousand Miles to Coast
High blood pressure, also known as hypertension, has often been called "the silent killer."  In the African-American community, it's presence seems almost genocidal. Forty-one percent of blacks have high blood pressure, as compared to 27% of whites. They develop it at younger ages and are more likely to suffer such complications as kidney diseases, stroke, blindness and heart disease.(Wed MD).  In searching for causes, a vigorous debate has arisen in the medical community. Some researchers point to genetic factors, believing that the problem is due to hereditary factors in the make-up of people with African ancestry.  Others, point to environmental factors such as the psychological strains of dealing with racism.   But as a historian, I may have stumbled upon an altogether different take on this vital subject.
 It occurred to me several years ago, that a misapprehension might exist in the medical community in regard to the specific geographical areas of West Africa from which most black Americans came.  It is understandable that medical researchers and the public alike would assume that black slaves came from the coastal areas of West Africa. If that were the case, they would certainly not have had diets deficient in salt, since their culinary traditions could draw from the briny waters of the Atlantic Ocean.  However, most African slaves came from the decentralized societies, which were located sometimes a thousand miles or more inland of the coast.  These areas, unlike the coast, are geologically deficient in sodium and coastal salt did not hold up well when transported long distances for purposes of trade.  I'm reprinting below a column I wrote in USA Today, February 16, 2001.

Pluses, minuses of racial distinctions
Preoccupied by yet another African-American friend's death from kidney disease, I sat at my desk distractedly flipping pages in a 16th-century chronicle from Timbuktu. Suddenly, the words of a passage about West Africa's then-flourishing gold trade flared off the page, jolting me out of my listlessness.  It wasn't the details of those now-depleted gold reserves that fired my attention, but the mention of a commodity then so rare and precious that West Africans readily would trade gold to acquire it: salt.My ancestors, brought to this country as slaves, came from the salt-deficient inland regions of West Africa, where gold was mined. Might a connection exist between the scarcity of salt in some black Americans' ancestral homelands and an apparent salt sensitivity that contributes to kidney disease?  A gene variant researchers have discovered in some African-Americans is believed to cause salt-sensitivity, increasing the risk of high blood pressure and kidney disease. It seems those super-efficient kidneys our forebears evolved so they could function on exceedingly low levels of salt now may be a problem for those of us who eat a salt-saturated American diet.
Defining the special dietary needs of some African-Americans is important. But I also recognize the inherent dangers in attributing specific medical issues to one race.  Research claiming to identify racial distinctions long has been used to construct bogus scientific theories justifying discrimination and bigotry. Skin color is an inefficient, even misleading, indicator of salt-sensitivity, because those of us who refer to ourselves as blacks usually have a mixed genetic heritage -- as, if the truth be told, do some Americans who think of themselves as "white." And not all African-Americans were brought here as slaves from salt-deficient inland regions of West Africa. Coastal Africans likely would not have this adaptation, while other "races" from salt-deficient geological environments in other parts of the world might.

I sometimes cringe when researchers, however well intentioned, make distinctions based on race. Despite this potential pitfall, understanding how our ancestral and geological heritage can affect our health
might even save lives.

UPDATED:

Rachael Maier has prepared an eye-opening chart offering visualizations of the sodium content of common foods.  Please take a look at these examples below and click here to read the entire chart (it may save your life!).