We are confronted yearly with new diets, each making claims for more effective weight loss, decreased risk of various illnesses and improved longevity.
Medical organizations generally advise diets that are low in sodium, animal fats and sugars. Dietary guidelines for Americans are updated every five years by agencies of the U.S. government. Changes in recommendations are based upon the best scientific evidence available.
The Mediterranean diet, first proposed in the 1970s, has gained increased support since the 1990s. Initial promotion of the diet was based upon studies of people in Spain, Italy and Greece who exhibited increased longevity compared to other European countries. Diet was considered the difference maker.
Compared to a typical American diet, the Mediterranean diet limits red meat to a few servings per month. Poultry or fish are substituted up to two times weekly. Fruits, vegetables, whole grains, legumes and nuts (unsalted and unsweetened) are consumed in multiple portions daily.
Spices and herbs take the place of excessive salt. Low-fat dairy products are used. Olive oil or other vegetable oils high in unsaturated fats are usually included as replacements for dairy and animal fats.
Somewhat controversial is the recommendation for a daily glass of red wine as a part of the Mediterranean diet regimen. Alcohol use may violate religious practices for some. Concern that regular wine consumption might lead to alcohol abuse must also be factored in.
A variety of clinical studies contend that regular adherence to the diet increases life expectancy and reduces the risk of such age-related disorders as cardiovascular disease, cancer and dementia. Many of these studies are short-term or retrospective, looking at a population from an historic perspective.
In 2013, a large, multicenter study from Spain and published in the New England Journal of Medicine compared the effects of three dietary protocols in a middle-aged population at risk for cardiovascular disease. All participants had regular dietary counseling.
The control group followed their usual diet but with encouragement to reduce fat intake. A second group followed the MD diet supplemented by extra-virgin olive oil. The third adhered to the Mediterranean diet supplemented with mixed nuts. After an average follow-up of 4.8 years, the two groups on the Mediterranean diet exhibited significantly fewer heart attacks, strokes or deaths from cardiovascular causes.
A 2014 study in the British Medical Journal provides a possible explanation for the beneficial effect of olive oil. Scientists used data from an ongoing evaluation of thousands of British nurses and found that the chromosomes of those who followed the Mediterranean diet were in better shape than those who didn’t. Healthier chromosomes are associated with longer lives and lower risks of age-related diseases. Subsequent studies must address the question of whether olive oil is the substance that protects the chromosomes.
If olive oil is included in the Mediterranean diet, it must be as a replacement, not a supplement, to other dietary fat.
Think of a tablespoon of olive oil as 120 calories and 14 grams of fat. The fats in olive oil are predominantly unsaturated which have anti-inflammatory properties. The fat content of an adult diet should not exceed 25 to 35 percent of calories consumed each day.
Solid science rather than fad should determine the content of a healthy diet. The Mediterranean diet is increasingly validated by an array of basic and clinical scientific studies. Future evaluations will determine if olive oil is a necessary component of the diet and or it it’s replaceable by canola or other vegetable oils.
Contact Clif Cleaveland at cleaveland1000@comcast.net.