A recent study published in the American Heart Association’s journal ‘Circulation’ found that protein supplements were linked with a reduction in blood pressure (1).
Lead researcher, Jiang He, M.D., Ph.D., said that the study’s results indicate that high blood pressure may be prevented or treated by partly replacing refined carbohydrates with foods or drinks high in soy or milk protein.
Each of the trial participants was randomly assigned to take 40 grams of soy protein, milk protein or a refined carbohydrate supplement every day for eight weeks each. They took the supplements as identical powders, dissolved into liquid. Each participant tried all three supplements, with a break of three weeks in between each one. Blood pressure was taken at the start and end of each 8-week phase.
The randomised, controlled trial tested 352 adults who had mildly elevated blood pressure, or who were at increased risk of the condition.
Each supplement was carefully formulated so that researchers could compare the effects of the protein and carbohydrate without changing levels of sodium, potassium and calcium.
Compared with carbohydrate supplements, both the milk protein and the soy protein supplements resulted in a significant reduction in systolic blood pressure.
"Some previous observational research on eating carbohydrates inconsistently suggested that a high carbohydrate diet might help reduce blood pressure," said Jiang He. "In contrast, our clinical trial directly compares soy protein with milk protein on blood pressure, and shows they both lower blood pressure better than carbohydrates."
It is not yet clear how the results of this study might affect dietary recommendations. Researchers claim that longer term studies will be needed before any specific recommendations can be made.
In the meantime, the following dietary recommendations could help you to prevent hypertension.
Limit refined carbohydrates Refined carbohydrates can result in sodium retention and increased insulin levels. This can raise blood pressure over time.
Limit sugary drinks and confectionary, and other refined carbohydrates such as white bread and white rice. Try switching to wholegrain bread, brown rice, wholegrain pasta and rolled oats.
Add milk or soy protein You can buy frozen edamame beans from the supermarket. Just boil these for a few minutes and then add to salads, soups and stews. Try firm tofu in stir-fries, soy milk in your tea, and snack on roasted soy nuts.
Try a serving of low fat natural yoghurt each day, or include an easy to digest protein supplement such as a whey protein shake.
Control your sodium intake For most adults, the daily upper limit for sodium is 2.3g. Those with high blood pressure and those over 50 should consume less than this.
Basing your diet around unprocessed, natural foods will lower your sodium intake. Make sure that tinned vegetables do not have added salt, and try to reduce the amount of salt used in cooking.
Other guidelines include avoiding excessive alcohol intake, quitting smoking and taking regular exercise. A heart-healthy diet such as the DASH diet can also help (2).
1. Jiang He, Marion R. Wofford, Kristi Reynolds, Jing Chen, Chung-Shiuan Chen, Leann Myers, Deborah L. Minor, Patricia J. Elmer, Daniel W. Jones, Paul K. Whelton. Effect of Dietary Protein Supplementation on Blood Pressure: A Randomized, Controlled Trial. Circulation, 2011; DOI: 10.1161/CIRCULATIONAHA.110.009159
2. DASH Diet Plan http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/new_dash.pdf