Why African Americans are prone to hypertension

African Americans are more susceptible to stroke and other cardiovascular diseases than any other ethnic group in the US.  According to recent statistics from the American Stroke Association

• Blacks have almost twice the risk of first-ever strokes compared to whites.
• Blacks have higher death rates for stroke compared to whites.
• The prevalence of high blood pressure in African Americans in the United States is the highest in the world.
• Among non-Hispanic blacks age 20 and older, 62.9 percent of men and 77.2 percent of women are overweight or obese.
• In 2001, 27.7 percent of black or African-Americans only, used any tobacco product. Heavy cigarette smoking approximately doubles a person’s risk for stroke when compared to light smokers.
• Black women have higher prevalence rates of high blood pressure, obesity, physical inactivity, and diabetes than white women.

This recent research at the Medical College of Georgia may give us a clue to this ethnic group’s susceptibility. It seems that a natural mechanism that regulates blood pressure is missing in many African Americans who are otherwise perfectly healthy. High blood pressure is a major risk factor for cardiovascular disease. Blood pressure can be increased by stress. However, the human body has a built-in mechanism that brings down the blood pressure. This system works by excreting more salt into the urine.

According to researcher Dr. Matthew Diamond

“The way it’s supposed to work is the higher your blood pressure goes, the system is supposed to be suppressed so you urinate out more sodium and the blood pressure goes down in response.”… The renin-angiotensin-aldosterone system helps regulate blood pressure, prompting the kidneys to hold onto more salt – and fluid – if it’s too low and to get rid of salt when it’s high.

However this mechanism that regulates blood pressure does not seem to work properly in about 1 in 3 adolescent African Americans. The study looked at 168 participants aged 15 to 18 years of age. The participants were healthy, non-obese, with normal blood pressure, and were placed on diets with controlled sodium and potassium. The researchers monitored their blood pressure, urine and blood samples while the participants were exposed to environmental stress through playing video games. The results showed that the renin-angiotensin-aldosterone system worked perfectly well in adolescents who were white but was improperly suppressed in about a third of black participants.

The reason for this dysfunction cannot be easily explained but may have some genetic explanation. The researchers are now planning to “screen participants for a genetic mutation that has been linked to hypertensive kidney disease to see if that’s a factor that can be used to help identify those at risk for hypertension and kidney disease.”

May is National High Blood Pressure Education Month in the US. The results of this study may just be the key understanding why African Americans are prone to hypertension and cardiovascular disease.

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