The University of Maastricht, which led this study, asked overweight test subjects to consume a drink with their meals for four weeks in a row. Half of the subjects were given a protein-rich drink that raised their protein intake by about ten percent in energy terms. The other half were given a carbohydrate drink. After one month, the subjects’ blood pressure was taken.
Big effect
The blood pressure of those who had received extra protein was lower than that of those on extra carbohydrates. Their systolic pressure had gone down by almost 5 mmHg, and their diastolic pressure by 2.7. ‘That is a big effect for a nutrition study’, says Marianne Geleijnse, who contributed to the experiment from Wageningen UR. ‘If the blood pressure of the entire Dutch population went down by five mmHg, we would expect 14 percent fewer deaths from strokes and nine percent fewer deaths from heart attacks’, says Geleijnse. The researchers do not yet know why the extra protein lowers blood pressure. Karianna Teunissen-Beekman, a Maastricht PhD researcher, is investigating this. It may be that the additional protein causes changes in the functioning of the kidneys, the bowels or the central nervous system, says Geleijnse. Because there is no clarity yet on this mechanism or on the possible disadvantages of an increased protein intake, consumers are not yet being advised to raise their protein intake.