Caffeine Effects

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Recently a study by the National Institute of Health (NIH) was published in which they analyzed the participants' use of coffee, tea, and caffeine and compared that to their risk of developing heart disease and the amount of coronary artery calcium as seen on cardiac CAT scans. The participants were followed for 11 years. Those who regularly drank tea (more than one cup per day) had less progression of coronary artery calcium and less heart disease than those who rarely drank tea (less than 1 cup per day) and those who never drank tea. Those who regularly or rarely drank coffee did not show any difference in the rates of coronary artery calcium and heart disease as compared to the study’s control subjects (non-coffee and tea drinkers). Likewise caffeine intake also had no effect. Not surprisingly they also found that those who regularly drank coffee and smoked, had higher rates of coronary artery calcium and heart disease.

So why would drinking tea, but not coffee have a beneficial effect on heart disease? Both products are derived from plants so why would there be a difference? The authors concluded the answer was that tea contains naturally occurring compounds called polyphenols and specifically a sub-type of polyphenols called flavonoids. Coffee does not contain flavonoids. Flavonoids are found in many plants and plant products like parsley, onions, blueberries and other berries, black/green/oolong tea, bananas, citrus fruits, red wine, dark chocolate (flavonoids are removed from most chocolate because they create a bitter taste), peanuts, and thyme to name a few. If this list of plants sounds familiar, it is because plants are the basis of a healthy type of diet that is suspected to reduce the risk of heart disease. That diet is called the Mediterranean diet.

The Mediterranean diet first became popular in the 1940s and 50s. It is based on the foods commonly consumed in Greece, southern Italy, and Spain. It is a plant-based diet and one of the main ingredients is olive oil. Also included in the diet are legumes (i.e. peanuts, peas, beans, and lentils), fruits, vegetables, unrefined cereals, fish, cheese, yogurt, and wine. Meats are avoided, as are fats, refined grains (i.e. white bread, white rice), and sugars. The Mediterranean diet is not a fad diet. Although one may lose weight on this diet, it is not a weight-loss diet per se, but rather a healthy way of living. It contains the food products on the food pyramid that are recommended by nutritionists.  It is a high-fiber, low fat and low sugar diet and is high in flavonoids.

To get back to the NIH study, more studies are planned to assess whether the protective association with tea consumption can be harnessed. Perhaps my mother, who used to buy loose tea and brew her own tea, was on to something all those years ago.

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