Diabetes Forecast June 2004
FOR TYPE 1/TYPE 2
Your Healthy Heart
Flavonoids
Nature's Paintbox And Medicine Cabinet
By Sheldon H. Gottlieb, MD, FACC
Come join me in my clinic, as we take a medical history from a patient who is new to me. He's in his late 50s, and he has had type 2 diabetes for about five years. He has had chest pain for several years, but recently the chest pain has gotten much worse; so much worse that he now has to stop to rest when he walks less than one block. His total cholesterol and triglycerides are both about 300 (very high). His HDL ("good" cholesterol) level is 35, which is low. He is taking a single oral medication for his diabetes, but no other medicines.
"Do you smoke cigarettes?" "Yes." "How much?" "About a pack a day." "Ever smoke more than that?" "Well, sometimes two packs a day." "How old were you when you started to smoke?" "About 11."
"How about alcohol, do you drink?" "Oh no!" "How about wine?" "Sure, I enjoy a glass of red wine every now and then." "How often?" "About one glass every two weeks." "Why do you drink wine every two weeks or so?" "I read in a magazine that red wine was good for my heart."
Belief in the medicinal value of wine is as old as wine itself. The Pharmacopoeia of the United States of America, sixth decennial revision, published in 1882, has listings for 14 different preparations of wine, from vinum album, or white wine, made "from the unmodified juice of the grape, freed from seeds, stems, and skins," to vinum rubrum, or red wine, made "by fermenting the juice of colored grapes in presence of their skins."
The deep, beautiful purple-red color of red wine is produced by a substance called anthocyanin, which is found in the skin of the grape. Anthocyanin is one of the four main groups of chemicals that together are called flavonoids. Flavonoids are found in many plants and especially in deeply colored fruits and vegetables.
We can thank anthocyanins for the deep red-blue color of red wine, the deep red-purple-black color of black olives, and the berry-red color of strawberries, cherries, and raspberries. Anthocyanin paints the northern countryside red when, in the fall, the sugar maple leaves produce less green chlorophyll. Without the green color of chlorophyll masking the anthocyanin and other flavonoid pigments in the maple leaves, the deeply colored red, orange, and yellow flavonoids in the leaves shine forth.
Flavonoids are important chemicals in plants; they regulate cell growth. Their medical use in humans was first described by a Hungarian scientist, Albert Szent-Györgyi, and coworkers, in 1936. These researchers discovered that certain flavonoids regulate how proteins leak out of injured blood vessels. The technical term for the process is "microvascular permeability."
Because of their effect on the permeability, or leakiness, of blood vessels, flavonoids were classified as a new vitamin: vitamin P. Although flavonoids are no longer classified as vitamins, research has shown many potential medical uses for flavonoids. For example, they regulate cell growth, function as antioxidants, and reduce inflammation and prevent blood clots.
Flavonoid-rich diets have garnered a lot of publicity lately. For example, you may have read about the so-called "French Paradox." The French Paradox is the observation that the coronary artery death rate in Finland was, for many years, almost four times higher than that in France, despite similar levels of animal fat consumption among citizens of both countries. However, even though the fat content was similar, there were striking dietary differences between the two cultures, especially in terms of patterns of alcohol use. Whereas French adults consume wine with their main meal on most days, "Finns have the traditional Friday and Saturday night of drinking to get drunk …" noted Ritva Varamaki, of the Finnish Health Promotion Center (The Baltimore Sun, Feb. 29, 2004, "Measure to lower prices on alcohol in Finland 40 percent").
Red wine may also reduce oxidative stress caused by increased blood glucose levels after meals, according to Antonio Ceriello, MD, and associates. In a research letter published in the December 1999 issue of Diabetes Care, Dr. Ceriello and associates presented data showing that consumption of two five-ounce glasses of red wine with a meal by subjects with type 2 diabetes significantly reduced the compounds produced by the test meal that could cause vascular damage by the mechanism of "oxidative stress." (Oxidation of LDL cholesterol causes fatty buildup in the arteries.) The protective activity of white wine was only about 20 percent that of red wine.
In a recent review article (Diabetes Care, May 2003) Dr. Ceriello suggests that large clinical trials have shown that antioxidant supplements such as vitamin E do not reduce coronary heart disease mortality or the damage caused by previously formed "oxidation products."
However, Dr. Ceriello also believes that the antioxidant power of flavonoid-rich foods such as red wine, apples, onions, green tea, and other deeply colored foods may protect against the causes of oxidative damage when they are consumed daily as part of a healthy lifestyle. Only future research will settle this matter for good.
So, will a glass of red wine every two weeks be "good for the heart" of someone with diabetes who also happens to smoke 20 to 30 cigarettes every day?
Probably not.
But is a daily diet of multicolored fruits, nuts, and vegetables, delightfully consumed with red wine or green tea, "good for the heart"?
If you're a scientist at heart, the answer is "probably—let's see more data."
But if you're a poet at heart, you already know the answer.
Sheldon H. Gottlieb, MD, FACC, is a cardiologist at Johns Hopkins Bayview Medical Center, Department of Cardiology, in Baltimore, Md. He also directs the Diabetes-Heart Failure Program at Johns Hopkins HealthCare, LLC.
