About 7500 middle-aged and older overweight adults in Spain recently finished almost 5 years of a nutritional study that compared strokes and heart attacks and related deaths in two groups eating a “Mediterranean” diet, one supplemented by even more olive oil and the other by more nuts (walnuts, almonds, and hazelnuts), compared to a third “control” group eating a higher starch (BRPPs: bread, rice pasta, potatoes) but somewhat lower fat diet.
The study, Primary Prevention of Cardiovascular Diease with a Mediterannean Diet, was recently published online in the New England Journal of Medicine February 25, 2013. The Mediterannean diet groups experienced about 30% fewer cardiovascular events in the study period compared to the control group. We should take heed.
However, some issues make it quite complex to understand exactly what “heed” we should take. Let me briefly cover a few of those issues.
Who Were the Study Participants?
The participants were all older Spaniards (above 55 for men and 60 for women), largely overweight (BMI averaged 30), and at high risk for cardiovascular disease (from Type II diabetes or a combination of hypertension, high cholesterol, smoking, and family history, or all of the above), but had not yet suffered an event. Remember, BMI of 30 means a 6 ft. tall man weighs 220 lb. and a 5 ft. 6 in. woman weighs 185. So these are not, on average, svelte parents and grandparents. They took medication for those various ailments. No special efforts were made to help them lose weight. And they were not shamed into going to the gym on a regular basis.
However, they were Spaniards, and at baseline all had been eating a Mediterranean diet, typically averaging about 1 oz. of olive oil per day with their food (such as on salads or used in cooking vegetables or protein). One study group was asked to raise its daily olive oil portion to 2 oz.; the second was asked to add 1 oz. tree nuts each day to the baseline 1 oz. olive oil; and the third group was asked to ratchet down all oils and sources of fat, including olive oil and nuts, and to increase carbohydrates (such as bread, rice, pasta and potatoes).
What Is the Mediterranean Diet?
The baseline “Mediterranean” diet differs slightly among the different Mediterranean countries, but the way it was defined in the study is typical. I believe the “serving” size is 3-4 oz., but still need to verify that:
- Lots of vegetables (2 servings/day) and fruit (3 servings/day) and legumes (beans and peas at least 3 servings/week)
- Little red meat or processed meat such as salami or hot dogs (less than 1 serving/day)
- Mostly fattier fishes (salmon, tuna, mackeral, blue fish, herring) at least 3 servings/week and poultry for protein
- Modest amounts of starch from rice, pasta, potatoes or bread, but no regular large portions
- Cooking with olive oil (extra virgin) at least 1 oz daily (including salads)
- Some tree nuts (at least 3 servings/week)
- 1 glass red wine each evening (or 2)
- Little butter, cream or margarine (less than 1 serving/day)
- Little soda (less than 1 glass/day)
- Little commercial bakery (including donuts, chips, muffins) less than 2 servings/week. Think, no Fritos.
The study group with “extra olive oil” essentially required another 1 oz. of olive oil (for a total of 2 oz. or 4 tbsp. per day used in cooking or on salads and consumed). The oil was specified as EVOO (extra virgin olive oil) because of the higher natural concentration of polyphenols in EVOO, which typically are substantially degraded when olive oil is processed. Polyphenols are strongly suspected to be among the most important healthy chemicals in olive oil. For situations where olive oil is not appropriate in cooking, canola oil may be a roughly comparable substitute, but that is not fully agreed to.
The study group for “tree nuts” continued to eat the baseline Mediterranean diet (including 1 oz. of olive oil) but added 1 oz. of a mixture of walnuts, hazelnuts and almonds, which are all high in linoleic acid, also thought to be the healthy chemical with anti-oxidant properties. The daily portion of 1 oz. represents at least a doubling of the baseline nut intake which itself is vastly more than typical in this country. Pecans should be as healthy. Peanuts and peanut butter may be acceptable partial substitutes, but not quite equivalent.
What Was the “Low-Fat Diet”?
The prescribed low-fat diet started with the baseline Mediterranean diet, but was supposed to reduce overall fat while retaining high amounts of fruits and vegetables, moderating use of olive oil, and still avoiding commercial baked goods, red meat and so forth. In practice, the diet reduced the amount of high-fat fish, but also moderately reduced ingested fruits and vegetables and legumes compared to the Mediterranean diet groups. Olive oil and nut use were down, but still higher than in this country. Red and processed meat remained low, but bread, rice, pasta and potatoes quantity was increased, though I had difficulty locating the exact amount despite extensively exploring the article’s appendices.
Then What’s the Summary?
Two groups of older, overweight Spaniards at high-risk for cardiovascular diseases followed healthy Mediterranean diets characterized by lots of vegetables, fruits and legumes, extensive use of olive oil in cooking, extensive use of fish, especially oily fishes, for protein, along with poultry, little red meat, small amounts of bread, rice, pasta and potatoes, little commercial baked food, little soda, little high-fat dairy, and at least one glass of red wine with the main meal. One of those groups added another ounce of olive oil daily, and the other an ounce of tree nuts daily.
The comparison low-fat group had clearly less vegetables, fruits, and legumes, much more starch, less fish, very little nuts, and modestly less olive oil than the baseline group. The measured amounts of fats in their diet during the study, whether saturated or unsaturated, were only about 10% less than either of the other groups.
The outcomes were a 30% reduction in strokes and in a combination of strokes, heart attack and cardiovascular deaths in either of the Mediterannean diet groups compared to the lower-fat group.
I think this study securely demonstrates that additional dietary olive oil or tree nuts, complementing a baseline healthy Mediterranean diet that is already high in olive oil, fish oils, fruits, vegetables and legumes and red wine, and low in starches and red meat, even applied to high-risk older diabetic patients, is clearly healthier than a diet with less olive oil and natural fish oil, less vegetables, fruits, and legumes, and more starches. The outcome is lower cardiovascular adverse events independent of weight loss or exercise.
- The Mediterranean style diet is really a very healthy diet.
- Key components are lots of olive oil, fish, vegetables, fruits and legumes.
- Nuts (walnuts, almonds, hazelnuts) are much more useful than I had realized. But pay attention to the 1 oz. (about 20 nuts) portions.
- Note the much lower intake of starches (BRPPS) than many of you follow.
- Note the avoidance of commercial bakery products like chips and muffins.
- Note lower use of red meat and processed meat.
- Note a glass of red wine in the evening for those of you who drink.
Personally, my favorite food to dine out is good Italian food. I think we know the Mediterranean diet is really tasty. This study is another demonstration that eating in this style is healthier than what many of us do and healthier than at least one version of a low-fat diet.