Rx Nutrition Resource Center

Rx Nutrition Resource Center

October 02, 2018
3 min read

Racial differences in incident hypertension driven by diet, education level

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George Howard

Racial differences in men and women regarding incident hypertension were related to the dietary ratio of sodium to potassium, Southern dietary pattern and education level, according to a study published in JAMA.

Other key factors in women but not men included BMI and waist circumference, according to the study.

REGARDS study data

George Howard, DrPH, professor in the department of biostatistics at University of Alabama at Birmingham School of Public Health, and colleagues analyzed data from 6,897 black or white participants (mean age, 62 years; 26% black; 55% women) from the REGARDS study aged at least 45 years with normal BP at baseline and available hypertension status at follow-up.

A telephone interview and an in-person examination were conducted at baseline to assess patients’ CVD risk profile, which included venipuncture, BP measurements, electrocardiography and measures of adiposity. Patients underwent a similar assessment during follow-up.

Researchers selected potential mediating factors that may have contributed to the racial difference in the level of the risk factor, prevalence or evidence of hypertension. These factors included education level lower than high school, BMI, income less than $35,000, heavy alcohol use, waist circumference, high depression scale score, lack of exercise, low Dietary Approaches to Stop Hypertension (DASH) diet score, high perceived stress scale score, high Southern diet score, low Mediterranean diet score and high ratio of sodium to potassium.

During follow-up for a median of 9.4 years; 46% of black participants (95% CI, 44-49) and 33% of white participants (95% CI, 32-34) developed hypertension.

The adjusted mean Southern diet score was 0.81 in black men (95% CI, 0.72-0.9), –0.26 in white men (95% CI, –0.31 to –0.21), 0.27 in black women (95% CI, 0.2-0.33) and –0.57 in white women (95% CI, –0.61 to –0.54).

The Southern diet was significantly associated with the risk for incident hypertension in men (OR = 1.16 per 1 standard deviation [SD]; 95% CI, 1.06-1.27) with an incidence of 32.4% at the 25th percentile and 36.1% at the 75th percentile (difference = 3.7%; 95% CI, 1.4-6.2). This was also seen in women (OR = 1.17 per 1 SD; 95% CI, 1.08-1.28) with an incidence of 31% at the 25th percentile and 34.8% at the 75th percentile (difference = 3.8%; 95% CI, 1.5-5.8).

Mediating factors

The largest mediating factor for the differences in hypertension incidence was the Southern diet for both black men (51.6%; 95% CI, 18.8-84.4) and black women (29.2%; 95% CI, 13.4-44.9).

The excess risk for incident hypertension in black men without a high school degree was 12.3% (95% CI, 0.6-23.9), whereas those with a higher dietary ratio of sodium to potassium intake accounted for 12.3% of excess risk (95% CI, 1.1-22.8).

The mediating factors for hypertension in black women were BMI (18.3%; 95% CI, 11.9-24.6), larger waist circumference (15.2%; 95% CI, 9.8-20.6), income less than $35,000 (9.3%), less adherence to the DASH diet (11.2%), education level of high school or less (4.1%) and higher dietary ratio of sodium to potassium (6.8%).

“The findings herein identified more mediating factors of the racial difference in incident hypertension in women than men,” Howard and colleagues wrote. “This may be partially attributable to an observed stronger association of race with incident hypertension among women than men that would provide greater statistical power to detect mediating factors.” – by Darlene Dobkowski

Disclosures: Howard reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.