At last, a large randomized, controlled trial (test and control, but apparently no placebo) to back-up the previous ‘observational’ studies:
The Mediterranean diet has long been touted as healthy. Now a study, released Monday, of the effects of a diet rich in olive oil, nuts, vegetables, fruits, and fish confirms that.
The study, published in the New England Journal of Medicine, showed that the diet can reduce the risk of stroke and other cardiovascular diseases by thirty percent.
Such a diet may seem like common sense, but researchers say the findings are significant because of the study's size and scientific rigor. It followed more than 7,400 people at risk of heart disease for nearly five years and measured the effects of the Mediterranean diet against a group that was assigned a low-fat diet.
The results were so significant that the ethics committee had to pull the plug early; the ordinary ‘low-fat’ diet (which wasn't really all that, but read on) was positively poisonous compared to the Mediterranean diet.
Next, researchers will need to study the Mediterranean diet (for instance, this one) on heart-disease patients. Previous heart-disease studies have shown that the benefits of aggressive ‘good behavior’ interventions (diet and exercise) pale in comparison to proper medications (ACE inhibitors, beta blockers, etc.); if they are taking the proper medicines, it's hard to detect a difference in outcomes between coronary heart-disease (CHD) patients who practice ‘good’ behavior and those who are simply ‘not bad’. (Bad behavior, however, is wholly destructive, so drop that T-bone and back away from the plate!) But maybe the Mediterranean diet will prove better.
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Dean Ornish is not so impressed:
Dr. Dean Ornish, UCSF professor and president of the nonprofit Preventive Medicine Research Institute in Sausalito, criticized the study, contending that the control group was not monitored carefully enough and wasn't assigned a truly low-fat diet.
‘A Mediterranean diet is a healthier diet than what most people are eating’, Ornish said. ‘The problem is [that] they claim ([that] the study) was comparing it to a low-fat diet, and it wasn't.’
Ornish said [that] the American Heart Association recommends a diet with fewer than 30 percent of calories coming from fat, but the control group's levels edged closer to 40 percent. Ornish, who promotes his own heart-healthy diet, urges people trying to reverse the effects of heart disease to cut that figure to as low as 10 percent.
It's a good point: 40% of calories from fat – 89 grams of fat given a 2,000 calorie diet – is not ‘low-fat’. This poor definition of ‘low-fat’ has plagued the low-fat vs. low-carb studies. The AHA's 30% threshold works out to 67 grams for a 2,000 calorie diet. Ornish is recommending something like 22 grams / 2,000 cal., which is about as tight as you can safely get. Fat is a necessary nutrient.
Also, as the doctor says, many diet studies have in fact been very poorly controlled. I remember, in particular, a low-carb vs. low-fat study out of Duke University – funded, of course, by the Atkins folks – that, in addition to not seriously limiting fats, didn't ensure that the subjects were actually eating what they were given and nothing else, never mind what they might have been drinking. Under those conditions, you can be sure that many were not following direction. Whether that effect was the same or different between the two groups is impossible to say, which completely invalidated the results.
That said, please note that Dr. Ornish's 10% recommendation is for people who already have heart disease. The AHA's 30% figure is probably adequate for the rest of us.
When I was losing weight (ah, those were the days!), I limited myself to between 20 and 30 grams of daily fat within a 1,600 calorie diet, which works out to between 11% and 17% of calories. I kept a very close eye on saturated fats (eggs and red meat were allowed, within the specified limits), and everything over twenty grams was limited to such sources as soy, peanuts, olive oil, and fish. With exercise, my weight and LDL cholesterol plummeted and my HDLs came up enough to matter. And yes, I did keep a planning-and-logging spreadsheet. I don't obsess about much (ask my housekeeper!), but when I do it's brilliant!
(Here's an experiment for you: If you want to see a doctor weep for joy, follow his advice.)