Genes Tied to High Blood Pressure Found in Black Americans
Study findings may lead to discovery of useful targets for new treatments, researcher says By Robert PreidtMonday, September 16, 2013
MONDAY, Sept. 16 (HealthDay News) -- Black Americans are more likely to develop high blood pressure than whites, and now a large new study has pinpointed four common genetic variations affecting their risk.
The study included nearly 30,000 black Americans at 19 sites across the United States and is the largest study to look at how genes influence blood pressure in black people, according to the researchers.
The investigators pointed out that most gene discoveries to date have been in white people and noted that previous studies in blacks failed to identify any genes associated with blood pressure.
Genes account for 40 percent to 50 percent of a person's risk for high blood pressure (hypertension). The four genetic variations identified in this study also affect other racial/ethnic groups, the researchers noted. Other risk factors for high blood pressure include lifestyle, diet and obesity.
The study also confirmed the role of other genes in increasing the risk of high blood pressure.
"In addition to their disproportionate suffering, hypertension occurs earlier in life for African Americans compared to individuals of other ancestries," study co-senior author Xiaofeng Zhu, a professor of epidemiology and biostatistics at Case Western Reserve University, said in a university news release. "Therefore, it is important to study this population to better understand genetic susceptibility to hypertension."
The findings were published recently in the American Journal of Human Genetics.
"Although it is unknown how the genes regulate blood pressure, our findings contribute to better understanding of blood pressure pathways that can lead to future development of drug target for hypertension and may guide therapy for clinical care," Zhu added.
Study co-senior author and geneticist Brendan Keating, of the Center for Applied Genomics at the Children's Hospital of Philadelphia, noted that "the research findings do not have immediate implications for treatment, but the hope is that discovering genes associated with disease risks will bring scientists closer to biological pathways and may suggest useful targets for new treatments." Keating is also with the department of pediatrics at the University of Pennsylvania.
SOURCE: Case Western Reserve University, news release, Sept. 10, 2013
The Dietary Approaches to Stop Hypertension (DASH) diet, which promotes consumption of more fruits, vegetables, low-fat dairy products, and whole grain, and less meats and sweets, is a proven effective treatment for hypertension. For some individuals, adherence to the diet can be just as effective in lowering blood pressure as taking antihypertensive medication. A new study has found that greater adherence to the diet can lead to significant reductions in blood pressure, but that African Americans are less likely to adopt the diet compared to whites. The study is published online today in the Journal of the Academy of Nutrition and Dietetics.
“After DASH dietary counseling, African Americans increased their consumption of DASH foods, but continued to lag behind whites in overall adherence to the DASH eating plan, consuming considerably more meat, sweets, and fat, and less fruit,” reports lead investigator James A. Blumenthal, PhD, Professor of Behavioral Medicine in the Department of Psychiatry and Behavioral Sciences at Duke University Medical Center in Durham, NC.
The study was a new analysis of the ENCORE study, which evaluated the effectiveness of the DASH diet alone and in combination with exercise training and weight reduction. 144 sedentary, overweight, and obese adults with high blood pressure were randomly assigned to three treatment groups. The first group ate the DASH diet and was engaged in weekly education, support, and feedback in group sessions. The second group also ate the DASH diet and received structured support and feedback, and in addition began a weight management program with caloric restriction, behavior modification, and aerobic exercise three times a week. The third group was instructed to maintain their normal diet and activity, but did not receive in instruction in the DASH diet nor were they encouraged to exercise or lose weight.
Researchers evaluated adherence to the diet, clinic and ambulatory blood pressure, and cardiorespiratory fitness. Participants also underwent a number of psychosocial assessments to evaluate their mental and social wellbeing and to identify potential predictors of dietary adherence including depression, anxiety, level of support from family and friends, and their beliefs about health and exercise. Demographic and background variables, including sex, age, ethnicity, income, education, and baseline body mass index were also examined.
After four months, participants in the DASH plus weight management group lost more weight compared to the DASH diet alone and control groups. There was no difference in dietary compliance between the DASH plus weight maintenance and the Dash alone groups. Participants with higher post-treatment DASH adherence scores had lower blood pressure levels, and the more participants adhered to the daily recommendations in the diet, the more their blood pressure decreased.
While both African-American and white participants in the DASH treatment groups increased their consumption of DASH foods after treatment, African Americans in both treatment groups had lower adherence scores compared to whites. No other demographic, behavioral, or social variable predicted DASH adherence.
“Strong cultural influences on food preferences, food preparation, and perceptions about eating practices might make it more challenging for African Americans to adhere to the DASH diet,” Dr. Blumenthal notes. “In light of the considerable role that food plays in African-American culture, greater cultural sensitivity is likely to be needed to achieve greater adoption of the DASH eating pattern when prescribing dietary modification programs. For example, it might be more effective to modify traditional recipes to meet current nutritional guidelines rather than to recommend that such foods be eliminated altogether.”
In a video accompanying the article, co-investigator Pao-Hwa Lin, PhD, a nutritionist from the Department of Medicine at Duke University Medical Center, discusses the implications of the study and possible reasons for lower adherence to the DASH diet in African Americans.
(HealthDay News) -- Secondhand smoke has a substantial health and economic impact, especially among black Americans, a new study shows.
Researchers analyzed data from more than 12,000 adults to assess the number of deaths, the years of potential life lost and the value of lost productivity caused by secondhand smoke in 2006.
That year, more than 41,000 American adults and nearly 900 infants died of secondhand smoke-related diseases, according to a journal news release.
The study found that blacks had significantly higher levels of exposure to secondhand smoke than whites. The highest exposure was among black men aged 45 to 64 (nearly 64 percent), followed by black men aged 20 to 44 (nearly 63 percent).
Black women aged 20 to 44 had a higher exposure rate (nearly 63 percent) than any other women.
In 2006, black infants accounted for 24 percent to 36 percent of deaths caused by mothers smoking during pregnancy, even though they accounted for only 13 percent of the infant population.
The toll from just two adult and four infant conditions linked to secondhand smoke in 2006 was 42,000 deaths, 600,000 years of potential life lost and $6.6 billon in lost productivity. Blacks and Hispanics had the highest value of lost productivity per death.
"With the high rates of smoking prevalence and the resulting high rates of [secondhand smoke] exposure in the United States and in many parts of the world, interventions need to be designed that target particularly vulnerable groups and that reduce the health and economic burden of smoking on smokers and nonsmokers alike," wrote Wendy Max, of the Institute for Health & Aging in San Francisco, and colleagues.
The study was published online Sept. 20 in the American Journal of Public Health.
(HealthDay News) -- People who stick with the so-called "DASH diet" achieve significant reductions in blood pressure, but blacks are less likely than whites to adopt the diet, researchers have found.
The DASH (Dietary Approaches to Stop Hypertension) diet -- which is rich in healthy foods such as fruits, vegetables and low-fat dairy items, and low in fats and cholesterol -- has been proven to help lower blood pressure.
In this study, Duke University Medical Center researchers examined whether adherence to the DASH diet was associated with blood pressure changes and what factors predicted who would stay with the diet.
The study included 144 sedentary, overweight or obese adults who had hypertension (high blood pressure) and were not taking blood-pressure lowering medications. They were randomly assigned to one of three groups: DASH diet alone; DASH diet plus weight-loss counseling and aerobic exercise; or no change in diet and exercise habits.
After four months, participants in the DASH diet/counseling/exercise group lost an average of 19 pounds. Weight remained stable in the other two groups, the investigators found.
Participants in both DASH diet groups had significant reductions in blood pressure levels, and those who adhered most closely to the diet had the largest drops in blood pressure. This suggests that following the DASH diet lowers blood pressure, independent of exercise and weight loss.
But the study found that exercise and weight loss in addition to the DASH diet promoted even greater reductions in blood pressure and improved other measures of heart health.
The researchers also discovered that blacks were less likely than whites to adopt the DASH diet. No other factor predicted whether participants would stick with the diet, according to the study published online Sept. 19 in the Journal of the Academy of Nutrition and Dietetics.
The findings suggest that altering traditional recipes rather than eliminating certain foods altogether might improve black patients' adherence to the DASH diet.
"We need to be aware of cultural differences in dietary preferences in order to help people better adopt a DASH-friendly diet," James Blumenthal, a professor of behavioral medicine, said in a Duke news release. "It is important to take into account traditional food choices and cooking practices when attempting to incorporate more DASH foods into daily meal plans."