SAN DIEGO – Low adherence to the Dietary Approaches to Stop Hypertension diet, including increased intake of dietary sodium and sweetened beverages, predicted vascular dysfunction and insulin resistance among a cohort of healthy black women, regardless of body weight.
Although the reason for the association remains unclear, genetic susceptibility and lifestyle factors may play a role, Dr. Priscilla E. Pemu said in an interview during a poster session at the annual meeting of the Obesity Society. Endorsed by the National Institutes of Health, the principles of the DASH diet are based on a low-sodium eating plan rich in fruits and vegetables, along with low-fat or nonfat dairy products (www.dashdiet.org).
Dr. Priscilla E. Pemu
"One of the main components of the DASH diet is intake of low-fat dairy products," said Dr. Pemu, an internist at Morehouse School of Medicine, Atlanta. In the black population, "there tends to be avoidance of dairy products because of lactose intolerance. Offering people alternatives – things they can tolerate – would be important in this population."
Dr. Pemu and her associates enrolled 52 healthy, normotensive, lean and obese black women (aged 18-45 years) in an effort to determine the contribution of dietary factors to vascular dysfunction. The women completed the Willett Food Frequency Questionnaire, and blood was collected for measurement of endothelial progenitor cells, C-reactive protein, adiponectin, tumor necrosis factor–alpha, and insulin resistance by homeostasis model assessment (HOMA), in which a level of 2.2 or greater was defined as insulin resistance.
The researchers also used high-frequency ultrasound to measure flow-mediated dilatation and nitroglycerine-dependent dilatation.
Study participants had less adherence to a DASH-type diet, compared with a reference population from the Nurses’ Health Study (Arch. Intern. Med. 2008;168:713-20), as evidenced by lower mean dietary intake of fruits per day (1.27 vs 2.19*, respectively), as well as a significantly higher mean daily intake of sodium (2,360 mg vs. 2,070 mg) and number of daily servings of sweetened beverages (2.33 vs. 0.26).
Lower DASH adherence scores among the study participants were associated with worse nitroglycerine-dependent dilatation, a correlation that was unaffected by age, blood pressure, or body mass index, Dr. Pemu reported.
Low DASH adherence scores, including higher intake of sodium and sugar-sweetened beverages, also predicted insulin resistance as measured by HOMA.
Based on these findings, Dr. Pemu recommends that black women "increase the amount of fruits and vegetables that they consume, as well as nuts, legumes, and low-fat dairy products, because we are starting to see a relationship with vascular dysfunction even in the absence of cardiovascular disease."
Dr. Pemu, who is also director of clinical trials at the clinical research center at Morehouse, acknowledged certain limitations of the study, including its small sample size and the potential for error in the self-reported food frequency questionnaires. "However, our data compared favorably with a much larger data set in the Nurses’ Health Study, giving us confidence in the relationships we have identified."
The study was supported by grants from the National Center for Research Resources. Dr. Pemu said that she had no relevant financial disclosures.
* CORRECTION, 1/4/2011: The original version of this article misstated the reference population's mean dietary intake of fruits and vegetables per day. This group consumed a mean of 2.19 servings of fruits and vegetables per day. This version has been updated.