Cholesterol-lowering 'portfolio diet' also reduces blood pressure, study finds
A diet developed for reducing cholesterol also lowers blood pressure, a St. Michael's Hospital study has found.
The research, published today in Nutrition, Metabolism and Cardiovascular Disease, was a secondary analysis of data collected for a 2011 study on the effect of the 'portfolio diet' on cholesterol.
The portfolio diet lowered blood pressure by an average two per cent, when compared with another diet recommended to reduce hypertension.
The portfolio diet includes foods that are scientifically-proven to lower cholesterol including mixed nuts, soy protein, plant sterols (found in vegetable oils and leafy vegetables) and viscous fiber (found in oats, barley and eggplant). The comparison method, a dietary approach to stopping hypertension, or DASH diet, emphasizes fruit, vegetables and whole grains, reduced meat and dairy intake, and eliminating snack food.
"This is a very important secondary finding to the original study, adding to the literature connecting diet with health," said Dr. David Jenkins, the study's lead author, director of the Risk Factor Modification Centre at St. Michael's and professor of nutritional sciences and medicine at the University of Toronto. "It fills in yet another area we often worry about. We can now say the dietary portfolio is ideal for reducing overall risk of cardiovascular disease."
The modest, two per cent reduction in blood pressure on the portfolio diet is in addition to the five to ten millimeter blood pressure improvement associated with a DASH-type diet. Although the DASH diet had higher compliance rates, the portfolio diet was more effective in reducing blood pressure.
High blood pressure and cholesterol are major risk factors for cardiovascular disease and stroke, historically treated with medications. However, Dr. Jenkins' research and work focuses on dietary and lifestyle changes to reduce risk factors.
"Dietary approaches have been found to be as effective as the starting dose of the average single blood pressure medication," said Dr. Jenkins. "Overall, research has shown that plant-based diets emphasizing foods higher in protein, oil and fiber reduce the risk of cardiovascular disease and stroke."
Previous research and studies have found that individual components of the dietary portfolio (mixed nuts, soy protein and viscous fiber) are effective at reducing blood pressure.
Dr. Jenkins said the diet's positive effect on cholesterol has already impacted guidelines in Canada and Europe.