Partially substituting carbohydrate with either protein or monounsaturated fat can lower blood pressure, improve lipid levels and reduce estimated cardiovascular risk, according to a study that appeared in the Journal of the American Medical Association.
Researchers randomized 164 adults with pre-hypertension to three different diets:
- A diet rich in carbohydrates
- A diet rich in protein—about half derived from plant sources
- A diet rich in unsaturated fat—predominantly monounsaturated fat
Each dietary period lasted six weeks, and body weight was kept constant.
The researchers write that blood pressure, LDL (“bad”) cholesterol and estimated coronary heart disease risk were reduced on each diet.
However, compared with the carbohydrate diet, the protein diet further
- Decreased systolic blood pressure by 1.4 mmHg and by 3.5 mmHg among those with hypertension
- Reduced LDL cholesterol by 3.3 mg/dl
- Increased HDL (“good”) cholesterol by 1.3 mg/dl
- Lowered triglycerides by 15.7 mg/dl
Compared with the carbohydrate diet, the unsaturated fat diet
- Decreased systolic blood pressure by 1.3 mmHg and by 2.9 mmHg among those with hypertension
- Had no significant effect on LDL cholesterol
- Increased HDL cholesterol by 1.1 mg/dl
- Lowered triglycerides by 9.6 mg/dl
“Compared with the carbohydrate diet, estimated 10-year coronary heart disease risk was reduced on the protein diet and similar on the unsaturated fat diets,” say the researchers.
—Journal of the American Medical Association,
November 16, 2005