The American Journal of Clinical Nutrition published new research last week that analyzed the effects of dairy on blood pressure (BP) in overweight, middle-aged men and women. Dairy has traditionally been regarded as unhealthy for adults in excess and bad for cardiovascular health.
The authors said the aim of the study was to investigate the effect of an HDD as compared with a low dairy diet (LDD) in participants, who consumed three meals per day over two separate six-week periods.
Those on the HDD were instructed to consume five or six portions of dairy per day, while those on the LDD consumed less than one portion. The HDD had to contain two portions of yogurt and about two slices of cheese every day, but the remaining portions were chosen by subjects.
In between the two six-week intervention diets, there was a four-week ‘washout’ period. Participants worked with a dietician to keep their intervention diets identical in calories and food patterns.
The dietician then calculated energy and nutrient intake from the subjects’ food diaries, analyzing the dietary intake of protein, calcium, sodium, potassium and magnesium.
At the end of the HDD, subjects had a slightly higher body weight, and thus a slightly higher BMI, than the LDD subjects. The calculated total energy intake was also significantly higher during the HDD than during the LDD.
In general, the researchers found that blood pressure levels were lower after the HDD than after the LDD, even when adjusted for body weight and ‘other potential confounders.’ They found a correlation between lower blood pressure and calcium intake, however.
“The BP-lowering effect of dairy in our study was explained by the concomitant increase in dietary intake of calcium. The BP-lowering effect was independent of the higher dietary intakes of protein, potassium, and magnesium, and also independent of lower dietary intake of sodium,” the study said.
“It can be hypothesized that calcium in combination with other minerals in dairy has a stronger effect on BP than calcium alone.”
“The present study introduces dairy as a possible nourishment that may contribute to the reduction of BP. Dairy may therefore contribute to the prevention of cardiovascular diseases.”
Two of the academics involved in the study are current employees of Dutch dairy cooperative FrieslandCampina.