A new report provides more evidence that a low-fat diet full of fruits and vegetables, but little salt, can lead to a significant drop in blood pressure.
The findings underscore the role that diet, specifically a low-fat diet called DASH, can play in lowering blood pressure, the study’s lead author told Reuters Health.
The report “re-emphasized the benefits of the DASH diet and a lower sodium intake for reducing blood pressure,” said Dr. George A. Bray of Pennington Biomedical Research Center in Baton Rouge, Louisiana.
In the study, 412 people were randomly assigned to a typical U.S. diet or the DASH diet (Dietary Approaches to Stop Hypertension). The DASH diet focuses on fruit, vegetables, low-fat dairy foods, whole grains, poultry, fish and nuts.
Researchers varied participants’ salt intake, with each group consuming high, medium and low levels of salt per day for a month at a time during the 3-month study.
At the start of the study, the subjects’ systolic blood pressure - the upper number in a reading - ranged from 120 to 159 millimeters of mercury (mm Hg) and diastolic pressure - the lower number - ranged from 80 to 95 mm Hg.
Blood pressure of 140/90 mm Hg or higher is considered high - even if only one number is elevated. A reading between 130/85 and 139/89 is considered high normal.
“Reducing sodium intake consistently reduced blood pressure across all participating groups,” Bray said.
The lower the reduction in sodium, the lower was the reduction in blood pressure, Bray and his team report in a recent issue of the American Journal of Cardiology.
The pressure-lowering benefits of cutting back on salt were consistent regardless of race, ethnicity, gender, age or previous blood pressure level, the study found.
When it comes to reducing blood pressure by cutting back on salt, lower may be better, the findings suggest. Although blood pressure dropped when people switched from high-sodium intake to medium intake, the drop was roughly twice as large when they switched from the medium intake to the low intake.
This suggests that it may be worthwhile to lower recommended sodium intake, as the medium level is the upper limit of current U.S. recommendations, according to Bray.
“Lower values for sodium intake could reduce blood pressure for most people,” Bray said.
Bray’s team also found that age was strongly related to the effect of sodium reduction and the DASH diet on blood pressure. The benefits of cutting back on sodium and going on the low-fat diet increased with age.
The researchers suggest that sodium reduction and the DASH diet should be recommended for preventing and treating high blood pressure because the benefits tend to increase once people enter middle age.
SOURCE: American Journal of Cardiology, July 15, 2004.
Revision date: June 14, 2011
Last revised: by Jorge P. Ribeiro, MD