Today’s post has nothing directly to do with mental health issues. However, since the cardiovascular fitness significantly affects the risk for psychiatric disorders – especially dementia -, I would like to report today on a very interesting study published in the New England Journal of Medicine on April 4, 2013, in which the influence of a Mediterranean diet on cardiovascular risk was studied (Estruch et al., N Engl J Med 2013, 368: 1279-1290). In a randomized multicenter study conducted in Spain 7447 subjects (57% women) who did not suffer from cardiovascular illness at inclusion in the study were observed for a median of 4.8 years. About one-third of the subjects fed themselves with a Mediterranean diet, which had been enriched by olive oil (extra-virgin), another third lived on a Mediterranean diet supplemented with nuts. The control group was given the instruction to eat a low fat diet. The groups who supplemented their Mediterranean diet with olive oil or nuts got a free liter of olive oil a week or 30 grams of nuts a day (15 walnuts, 7.5 g hazelnuts, almonds 7.5 g), respectively. The control group received small non-food gifts. Caloric intake was not restricted, and physical activity was not particularly recommended. The primary endpoint was a composite of heart attack, stroke or death from a cardiovascular event. Secondary endpoints were heart attack, stroke, death from a cardiovascular event or death from any cause.
Participants were regularly trained individually and in group sessions to adhere to the following diets:
- Olive Oil ≥ 4 Tablespoons/Day
- Tree Nuts and Peanuts ≥ 3 Servings/Week
- Fresh Fruits ≥ 3 Servings/Day
- Vegetables ≥ 2 Servings/Day
- Fish (esp. fatty fish), Seafood ≥ 3 Servings/Week
- Legumes ≥ 3 Servings/Week
- Sofrito ≥ 2 Servings/Week
- White Meat Instaed of Red Meat
- Wine with Meals (optional) ≥ 7 Glasses/Week
- Soda Drinks < 1 Drink/Day
- Bakery Goods, Sweets, Pastries < 3 Portionen/Woche
- Spread Fats < 1 Serving/Day
- Res and Processed Meats < 1 Serving/Day
Low–Fat Diet (Control Group):
- Low-Fat Dairy Products ≥ 3 Servings/Day
- Bread, Potatoes, Pasta, Rice ≥ 3 Servings/Day
- Fresh Fruits ≥ 3 Servings/Day
- Vegetables ≥ 2 Servings/Week
- Lean Fish, Seafood ≥ 3 Servings/Week
- Vegetable Oils (incl. Olive Oil) ≤ 2 Tablespoons/Day
- Bakery Goods, Sweets, Pastries ≤ 1 Serving/Week
- Nuts, Fried Snacks ≤ 1 Serving/Week
- Res and Processed Fatty Meats ≤ 1 Serving/Week
- Visible Fat in Meats and Soups Always Remove
- Fatty Fish, Seafood Canned in Oil ≤ 1 Serving/Week
- Spread Fats ≤ 1 Serving/Week
- Sofrito ≤ 2 Servings/Week
The subjects in the group who supplemented their diet with olive oil were asked to use only the provided oil (at least 50 g/day, equivalent to about four tablespoons), as this is rich in polyphenols. The usual refined oil is low in polyphenols. Sufrito is a sauce of tomatoes and onions, often with garlic and other spices, which is slowly simmered with olive oil.
At baseline the participants were on average 67 years old (range 55 – 80). 97% were white with European origin. Approximately 14% of participants in all groups were current smokers, 24-26% were former smokers. They were on average overweight, the mean BMI was 30. Only 7 or 8% had a BMI at baseline below 25. Vascular risk factors were present to a significant degree: 82-84% had hypertension, 47-50% had type II diabetes and 72-73% had dyslipidemia.
The subjects were observed for a total of between 9763 years (control group) and 11,852 years (olive oil). 11.2 events per 1000 person-years occurred in the control group, but only 8.1 (olive oil) and 8.0 (nuts) events in the groups fed with a Mediterranean diet. Thus, in both groups on a Mediterranean diet occurred statistically significantly less events than in the control group (olive oil vs. control: p = 0.009; nuts vs. control. P = 0.02.). Regarding the secondary endpoints, the Mediterranean diet significantly reduced the number of strokes (5.9 events per 1000 person-years in the control group; 4.1 events in the olive oil group, P = 0.03; 3.1 events in the nuts group, p = 0.003).
Overall, the study shows that a Mediterranean diet, even if it starts relatively late, reduces cardiovascular risk by 30% compared with a low-fat diet. A PDF of the paper can be obtained from me. I will discuss the cognitive effects of the Mediterranean diet, which was also examined by the authors, in a separate post in the future.
This post is also available in: German