DASH diet: more than high blood pressure?

For years the go-to diet for treating high blood pressure has been the DASH diet. It was, after all, devised by the National Institute of Health (NIH) for that exact purpose, hence its name: Dietary Approaches to Stop Hypertension. There's significant research to demonstrate that it's an effective means of treating high blood pressure in those who are already hypertensive, but it's also been shown to improve scores in those whose blood pressures are nearer normal.

High blood pressure is just one of the risk factors for cardiovascular disease, however. What about other risk factors, such as cholesterol scores or glucose levels? There have been studies that looked at the incidence of heart disease or stroke, but data on the specific risk factors has been somewhat lacking. Researchers in the UK reviewed the available published studies to see if some conclusions might be drawn on the effects of a DASH diet on other heart disease factors (Brit J Nutr 2015;113:1-15).

For their meta-analysis Dr. Siervo and his team gathered research articles that were randomized, controlled trials comparing a group following a DASH diet to a control group and measured risk factors including blood pressures, glucose scores, and cholesterol scores. The 20 articles they found included a total of over 1,900 men and women and the studies lasted from 2 to 24 weeks.

After analyzing the pooled results, it shouldn't surprise you that a DASH diet did indeed result in improved blood pressures, with stronger results seen for those participants with higher starting blood pressures or higher Body Mass Indices. The DASH diet also helped improve total and LDL cholesterol scores (remember that LDL is the "bad" cholesterol). No effect was seen on HDL cholesterol scores (the "good" cholesterol), triglyceride levels, or glucose scores.

What we found particularly interesting about this article is that the authors note, "the lack of a significant association between changes in BP [blood pressure] and dietary Na [sodium] intake is unanticipated." For the past several years there have been small indications that dietary sodium - the amount of sodium in your diet - is not the single cause of high blood pressure. Don't take this to mean that you should stop worrying about sodium altogether. We know that sodium intake does matter: cutting salt from your diet does help reduce blood pressures. But it's equally clear that sodium is just one factor.

What this means for you

We will still continue to advocate for a Mediterranean-style diet for the vast majority of our patients (and here on the website). The research into the effects of a Mediterranean-style diet go far beyond blood pressures and total cholesterol scores into improving HDL cholesterol scores, improving glucose tolerance, and helping reduce inflammation, among others. Here's more on the Mediterranean Diet.

First posted: January 14, 2015