Study says raw, not cooked, vegetables are better at lowering blood pressure.
While hypertension is key independent risk factors for major heart diseases, affecting about 25 percent of U.S. adults, several studies have reported lower average blood pressure levels in vegetarians compared with non-vegetarians.
Most of these studies found a link between blood pressure and the combined consumption of fruits and vegetables. The International Study on Macro/Micronutrients and Blood Pressure (INTERMAP), for example, found a significant inverse relation between vegetable protein intake and blood pressure as well as between blood pressure and dietary glutamic acid — the most common dietary amino acid, especially in vegetable protein.
However, studies have not compared the effect of raw versus cooked vegetable on blood pressure. This could be significant, because the processing of vegetables influences their chemical composition and nutritional value. For example, raw green leafy vegetables have significantly higher levels of antioxidants than cooked and the bioavailability of carotenoids from cooked tomatoes is higher compared with raw. The only data available compares the intake of a few individual vegetables (raw or cooked) with blood pressure. That is, until now.
In a complex study of 2,195 American men and women who were part of INTERMAP, an international team of researchers found that eating raw vegetables is more effective in lowering blood pressure than cooked vegetables. The link was especially significant among 12 commonly consumed raw vegetables such as tomatoes, carrots, and scallions; and among commonly consumed individual cooked vegetables — tomatoes, peas, celery, and scallions.
The researchers, whose study appears in the latest Journal of Human Hypertension, concluded that calculation of the wholesomeness of raw versus cooked vegetables is complex and the relationships between plant foods and human biological systems, as well as the possible mechanisms of these relationships remain largely unidentified. However, their data on vegetables and blood pressure shows “that higher intakes of both raw and cooked vegetables are aspects of an overall healthier and more nutritious diet. Thus, while etiologic conclusions on these relationships are presently premature, the multivariate controlled results support the concept that fare high in vegetables may reduce risk of adverse blood pressure, and support recommendations for high population-wide intake of vegetables, raw and cooked.”