2/28/17: WRAPPING UP NATIONAL HEART MONTH: The Mediterranean Diet, ‘Heart-Healthy’ Eating

 

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I wrap up my blogging this month with a look at what we call “heart-healthy” eating, that is, eating that does not drive up cholesterol levels and triglycerides in the blood, both of which contribute to the development of atherosclerosis.

Ever since a 1950s study of the dietary patterns of long-lived Crete islanders, nutritionists have promoted the Mediterranean diet as a model of healthy eating. (1) Crete is the largest of the Greek islands in the Mediterranean Sea. Sixty years ago, Cretans had markedly low rates of heart disease and cancer.

The “traditional Mediterranean diet,” according to a Greek epidemiologist and authority on the relationship between aging and nutrition, “is characterized by a high intake of vegetables, legumes, fruits and nuts, and cereals (that in the past were largely unrefined), and a high intake of olive oil but a low intake of saturated lipids, a moderately high intake of fish (depending on the proximity of the sea), a low-to-moderate intake of dairy products (and then mostly in the form of cheese or yogurt), a low intake of meat and poultry, and a regular but moderate intake of ethanol, primarily in the form of wine and generally during meals.” (2)

Unsaturated Fats

A key distinction of the Mediterranean diet is the consumption of poly- or mono-unsaturated fats, such as olive oil, rather than saturated fats, such as butter or margarine. In the Mediterranean region, early researchers discovered, people dipped their whole-grain bread in fat-healthy olive oil, not in butter or margarine, which contains saturated fats.

Fats (lipids) are an essential ingredient of our diet, serving many functions in our bodies. But just as there is good cholesterol and bad cholesterol—cholesterol is a fat— different fats pose different health consequences. (For a review of cholesterol, see my 2/8/17 and 2/1/17 blogs.)

Saturated and unsaturated fat molecules have a similar chemical structure—a chain of carbon atoms bonded to hydrogen atoms with a carboxyl group (COOH) at one end—but they differ by the length and shape of the carbon chain and by the number of hydrogen atoms connected to carbon atoms. (The carboxyl group is the reactive part of the molecule. The Harvard Medical School provides a good overview of saturated and unsaturated fats at http://www.health.harvard.edu/staying-healthy/the-truth-about-fats-bad-and-good. I am not a chemist, nor do I pretend to be.)

Saturated fats are saturated with hydrogen. They have all of the hydrogen that they can hold. (See above illustration.)

Saturated fats are also solid at room temperature (think cooled bacon grease or Crisco), whereas unsaturated fats are liquid (think canola oil). Saturated fats typically come from dairy products, such as whole regular milk and cheese, and meats, especially red meats.

“The more often you visit the golden arches,” joked Robert Blumenthal, M.D., cardiologist and director of the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, at a seminar I attended, “the closer you get to the pearly gates.” (3)

The carbon atoms of unsaturated fats can hold more hydrogen. Those that are mono-unsaturated have only one carbon atom that still has room for a hydrogen atom, whereas polyunsaturated fats have many carbons that can take more hydrogen.

So-called “trans” fats—again, this refers to chemical structure—are artificially hydrogenated unsaturated fats. Food manufacturers add hydrogen to unsaturated fats (oils) to improve texture and other cooking properties, but in the process, create more saturated fat.

Unsaturated fats are the good fats—although not if you’re trying to lose weight. I’m talking only about artery and heart health. Polysaturated and monounsaturated fats can help reduce blood levels of bad low density lipoprotein (LDL) cholesterol, which is more likely to build up as plaque in your arteries. Saturated fats, especially trans fats, create inflammation and drive up cholesterol levels.

You have probably heard of the health benefits of omega-3 fatty acids, which are polyunsaturated fats whose only source is food. Our bodies do not make omega-3 fatty acids. These fatty acids reduce blood pressure, raise the good HDL cholesterol, which picks up excess cholesterol in the bloodstream and takes it to the liver for breakdown; and lower triglycerides.

DASH Diet

Most healthy diets include fruits, vegetables, fish, and whole grains and discourage unhealthy fats. Mediterranean dieters also season their food with herbs and spices, rather than salt, and eat nuts, such as almonds, cashews, and walnuts, for snacks—but no more than a handful a day because of their high caloric content. (Most fat in nuts is not saturated.)

Fish is eaten on a regular basis with the Mediterranean diet. Fatty fishes, such as albacore tuna and salmon, are good sources of omega-3 fatty acids. Of course, fried fish, cooked in saturated fat, should be avoided. Not coincidentally, the island nation of Japan, where fish is a dietary staple, has long ranked in the top-five nations worldwide in terms of longevity.

Long-term studies of Europeans elders (ages 70 to 90) have consistently shown that an adherence to a Mediterranean diet, in combination with other healthy practices such as exercise and abstention from smoking, significantly lowers their risk of mortality from all causes, including cardiovascular disease. (4) Notably, all long-lived elders in such studies engaged in moderate alcohol consumption and moderate to high physical activity and either did not smoke or quit smoking more than 15 years before the respective study.(5)

The plant-rich Mediterranean diet, which eschews saturated fats in favor of monounsaturated fats, served as the prototype for the low-sodium Dietary Approaches to Stop Hypertension or “DASH” diet, which U.S. cardiologists now recommend. (6)

According to the Mayo Clinic, the DASH diet “emphasizes vegetables, fruits, and low-fat dairy foods—and moderate amounts of whole grains, fish, poultry, and nuts,” but also strictly limits sodium intake. The “standard” DASH diet allows a daily sodium intake of 2300 mg.; the lower-sodium DASH diet, which the American Heart Assn. recommends for all adults, caps it at 1500 mg. Besides salt, a lot of dietary sodium comes from processed foods.

The DASH diet also encourages the consumption of foods rich in the nutrients, potassium, magnesium, and calcium, which are believed to lower blood pressure.   

The diet is designed to prevent or help treat high blood pressure (hypertension), which, as I’ve explained in earlier blogs this month, is a risk factor for atherosclerosis and heart disease. Although the point of the DASH diet is not to lose weight, it is also calorie-conscious. Obesity is a risk factor for hypertension, as well as diabetes type 2. See the Mayo Clinic at http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/dash-diet/art-20048456  and the National Heart, Lung, and Blood Institute at https://www.nhlbi.nih.gov/health/health-topics/topics/dash for more information about the diet and for meal plans.

Antioxidants

I conclude my overview of heart-healthy eating with a word about antioxidants, which are a fairly hot topic.

While clinical evidence exists to support the belief that the consumption of fruits and vegetables rich in antioxidants, such as vitamins C and E, prevents disease, there is no evidence that the consumption of antioxidant supplements will thwart aging and prolong life. Data on their anti-aging benefits are lacking.

According to a former chief of medicine and distinguished medical professor emeritus at Vanderbilt University School of Medicine who has studied oxidative stress—believed to contribute to cell damage and mutation, which eventually lead to aging and death—the only promising dietary antioxidant is resveratol, which comes from the grapes used in producing red wines.

Resveratol may prove “heart-healthy,” in that it may help to increase levels of good cholesterol and protect against artery damage, but any definitive conclusions are years away. Preliminary indications from resveratol studies in mice suggest that a human being would have to drink over 60 liters of red wine every day to derive any benefit. At that rate of consumption, red wine is certainly not the drinking fountain that Ponce de Leon sought in vain.

Ann, 2/28/17

1. Frank B. Hu, “The Mediterranean Diet and Mortality—Olive Oil and Beyond,” New England Journal of Medicine 348 (2003): 2595-96

2. Antonia Trichopoulou, Tina Costacou, et al, “Adherence to a Mediterranean Diet and Survival in a Greek Population,” New England Journal of Medicine 348 (2003): 2600. See also Kim T.B. Knoops, Lisette C.P.G.M. de Groot, et al, “Mediterranean Diet, Lifestyle Factors, and 10-Year Mortality in Elderly European Men and Women: The HALE Project,” JAMA 292 (2004): 1434; and Hu, “The Mediterranean Diet and Mortality—Olive Oil and Beyond,” pp. 2595-96.

3. Dr. Roger Blumenthal, “Status of Statins,” seminar in “A Woman’s Journey,” presented by Johns Hopkins Medicine, Nov. 17, 2012, Baltimore, Md.

4. See Knoops, et al, “Mediterranean Diet, Lifestyle Factors, and 10-Year Mortality in Elderly European Men and Women: The HALE Project,” pp. 1433-39 and citations therein; and  Trichopoulou, Costacou, et al, “Adherence to a Mediterranean Diet and Survival in a Greek Population,” pp. 2599-2608.

5. See Michel, Newton, and Kirkwood, “Medical Challenges of Improving the Quality of a Longer Life,” pp. 689-99.

6. Hu, “The Mediterranean Diet and Mortality—Olive Oil and Beyond,” p. 2596.

 

 

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