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The Mediterranean Diet and Death in America
I've reported in the past on studies that investigate the Mediterranean Diet's effects on cholesterol (News Bite, 8/9/06) and heart disease (News Bite, 7/11/06). Recently the National Cancer Institute, in partnership with AARP, published the findings of a long term, large scale, prospective study (meaning the subjects were followed through time) on the Mediterranean Diet and its effects on all-cause mortality in the United States (Arch Intern Med 2007;167(22):2461-2468).
What is the DASH diet?
For the most part, the DASH Diet is the practical application of the Mediterranean diet. The research in the 1970s and 1980s about Mediterranean diet laid the foundation for great quality nutrition research in the 1990s. The result was a large scale, multi-center trial of 459 adults age 22 years or older.
The DASH Diet and the Mediterranean Diet
The DASH Diet (Dietary Approaches to Stop Hypertension) is so successful because its foundations are drawn from research on the Mediterranean diet. Many of the researchers who took part in the initial DASH study were the same who detailed the benefits of the Mediterranean diet. If you look at them side by side it's easy to see how similar they are.
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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 I 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
I will still continue to advocate for a Mediterranean-style diet for the vast majority of my patients (and here on the web site). 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