Q: I’ve heard that coconut is bad for the heart and that it’s good for the heart. Which is right?
A: Viewed in isolation, coconut and coconut oil can’t be considered heart-healthy foods. A 2-ounce piece of fresh coconut contains more than 13 grams of saturated fat – nearly two- thirds of the recommended daily limit for the average person. Ounce for ounce, coconut oil delivers more saturated fat than butter, lard or margarine. Feeding studies in humans, monkeys and rabbits show that coconut oil substantially elevates LDL (bad) cholesterol.
Viewed in context, though, coconut may not be so bad. Some food companies are testing coconut oil as a replacement for the once-ubiquitous partially hydrogenated vegetable oils, which contain hefty amounts of dangerous trans fats. Both coconut oil and trans fats increase LDL. But while trans fats reduce protective HDL, coconut oil has a powerful HDL-boosting effect.
Don’t take this as a ringing endorsement of coconut oil – I would much rather see food makers get rid of trans fats in our food supply by using unsaturated fats than by substituting coconut or palm oil. But when a hard fat is needed, coconut oil is an acceptable alternative, at least until better ones come along.
As you may know, books such as “The Healing Miracles of Coconut Oil” and “Coconut Cures” claim that coconut can prevent heart disease, dissolve kidney stones, control diabetes, protect against cancer, enhance the immune system, and maybe even prevent AIDS. There is no good evidence to back up these claims.
Do you need to avoid coconut? No. Fresh coconut is delicious; shredded coconut livens up pastries and granola; and who can resist a spicy coconut curry, or a piña colada at a beach party? But to take the best care of your heart and blood vessels, think of these as treats rather than as everyday choices.
– Dr. Walter C. Willett, Harvard Heart Letter Editorial Board
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Q: Three years ago, I had coronary bypass surgery. How long will my grafts last?
A: It depends on where your grafts came from. The most common sources are leg veins (the saphenous vein), arteries that supply the chest (the internal mammary artery), and arteries from the arm (the radial artery). Grafts made from leg veins tend to become blocked by cholesterol-filled plaque and blood clots over time, so that half or more close up within 10 years. Grafts made from internal mammary arteries resist such blockages, and most stay open for 20 years or more. Grafts made from radial arteries fall somewhere in between.
If you have vein grafts, don’t feel like your clock is ticking based on these numbers. In many people, as vein grafts narrow, the heart responds by growing new blood vessels that can compensate for the reduced blood flow. You can nurture the growth of these collateral vessels with regular exercise. If you do this and take care of your heart, the chances are good that even if your vein graft blocks, neither you nor your heart will notice it.
-Dr. Thomas Lee, Harvard Heart Letter
