Mediterranean Diet Advantages Not Limited to Normal Weight

A lot of articles about research studies make it sound like overweight or obesity is a direct cause of conditions such as heart disease and diabetes. This isn't true. While we know that there is a statistical link between having excess body weight and having heart disease, cancer or diabetes, we still do not fully understand the mechanism by which having body weight above the norm might contribute to or cause these conditions. While we've seen that those who are overweight or obese are more likely - even significantly more likely - to develop these conditions, the fact remains that there are persons who are overweight who do not develop these conditions.

We know that those people following a Mediterranean-style diet are less likely to be overweight or obese, and that a Mediterranean-style diet can help reduce blood pressure and improve cholesterol scores and insulin levels. But for those who are already overweight, are there advantages to a Mediterranean diet? Researchers in Greece used information from an ongoing health and nutrition survey to find out (http://www.lipidworld.com/content/6/1/22).

Over 1,700 clinically overweight or obese adult men and women consented to participate in the survey which began in May 2001. Of these participants, almost 40% had high blood pressure and 10% had type 2 diabetes. The participants provided demographic information such as age, financial status, smoking and physical activity, and the researchers tested their blood pressures, cholesterol scores and insulin concentrations.

Using a detailed dietary questionnaire, the researchers assessed the participants' usual diets in the areas of "non-refined cereals and products, vegetables, legumes, fruits, olive oil, dairy products, fish, pulses, nuts, potatoes, eggs sweets, poultry, red meat and meat products." The researchers compared each participant's usual diet with the Mediterranean dietary pattern and assigned the participant a score from 0 to 55, where a higher score meant higher adherence to a Mediterranean diet and a lower score described a more Western-style diet.

The researchers found that compared to those who scored in the bottom third of the Mediterranean diet score, those who scored in the highest third had 4% lower insulin levels, 6% lower glucose levels, and 13% lower total cholesterol. They also had slightly lower blood pressures.

However, once the researchers controlled for such variables as existing high blood pressure or diabetes, the relationship between Mediterranean diet score and insulin levels or diastolic blood pressures reduced to clinical insignificance. The reduction in systolic blood pressures (the top number in your blood pressure readin), remained statistically significant, even though that reduction would not be seen as important in a clinical sense.

What this means for you

The researchers in this study note that since this is a cross-sectional study (essentially a snapshot in time), it isn't able to establish any causal relationship between weight and blood pressure, cholesterol scores or other clinical tests. That said, what this study does show is that the benefits of a Mediterranean diet are not limited to those of normal weight. Eating healthier is great for you no matter what your body size.

First posted: May 4, 2011