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Dry, Wrinkled Fruit…Strong Bones

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Prunes…it’s not a particularly pleasant word nor a particularly pretty food, but these dark, wrinkly dried fruits are in the process of getting a facelift. Not only are marketers trying to make prunes more appealing by rebranding them as “dried plums” (which is what they are, of course), but the US Department of Agriculture (USDA) has funded some impressive research that puts muscle behind the makeover, cataloging a long enough list of nutritional benefits that prunes now can be considered a real “superfood.” The newest study, from Florida State University, finds that including prunes in your daily diet offers powerful protection against both osteoporosis and bone fracture.

Sweet Protection For Your Bones

Prunes are amazingly good at strengthening bones, said the study’s lead author, Bahram H. Arjmandi, PhD, RD, chairman of Florida State’s department of nutrition, food and exercise sciences in its College of Human Sciences. Having studied how various fruits, including figs, raisins and strawberries, affect bone health, Dr. Arjmandi said that prunes are uniquely helpful in preventing and/or reversing osteoporosis. That’s because they contain compounds that help suppress the natural process of bone breakdown more technically known as resorption—which is a big issue for older people since bone breakdown tends to exceed the rate of new bone growth as people age.

“Yes, you can take medication to make your bones stronger,” Dr. Arjmandi said, “but I don’t think you can compete with nature in producing anything that is as effective in promoting bone health, while also being healthy in other ways, as prunes are.”

This is some pretty dramatic talk—so let’s look closely at the study. It spanned one year and involved 236 women who were one to 10 years postmenopausal, either nonsmokers or who smoked 20 cigarettes per day or less, did not have any metabolic diseases and were not taking hormone replacement medication or any other medication that could influence bone health. For the study, half of the women ate 100 grams of prunes (about 10 prunes) each day, while the control group ate 75 grams of dried apple (equal to about two fresh apples, and comparable to the amount of calories, carbohydrates, fat and fiber in 100 grams of prunes). Participants’ diets remained the same as normal otherwise. Additionally, everyone in the study took daily doses of calcium (500 milligrams) and vitamin D (400 international units), as do many women.

After a year, a standard bone density x-ray of the ulna (one of two long bones in the forearm) and spine showed that, on average, the women who had been eating the prunes… er, dried plums… had significantly increased bone mineral density compared with their measured levels before eating prunes. The women who had been eating dried apples, on the other hand, did not lose any bone density during the year of the study, as would have been expected, and their bones showed a slight increase in bone density—indicating that apples are also slightly bone protective, but not to the extent that prunes are. Other bones were measured, but the most dramatic changes were in the ulna and spine—which is gratifying because the ulna and spine are the two major fracture sites linked to osteoporosis.

Learn To Love Prunes

So, what is it about prunes that helps bones? First, they are unusually high in several types of phytonutrients including the antioxidants neochlorogenic acid and chlorogenic acid, which have been shown to prevent bone loss. Prunes contain larger amounts of boron than most other fruits, and boron helps preserve bone mineral density by modulating bone and calcium metabolism. Prunes also contain iron and potassium, important for blood and heart health.

The women in the study were asked to eat 10 prunes a day, which may be difficult for someone unaccustomed to eating prunes. But Dr. Arjmandi reckons that eating as few as three prunes a day will have important health benefits. I wondered whether all the sugar in prunes caused any problems—he told me that the glycemic index of prunes is about 27, among the lowest of all fruits, and that none of the women gained any weight during the study (which, he said, could be because prunes contain so much fiber). He added that prunes (unlike other dried fruits) don’t contain sulfites—good news for the many folks who are allergic to this common preservative. To prevent mold and yeast spoilage, the preservative potassium sorbate, which is generally regarded as safe and is unlikely to cause allergic reactions, is used. But anyone who wants to avoid it can find prunes that are preservative-free in health-food stores and online.

And what about the laxative effect so often attributed to prunes? They have lots of fiber, including insoluble fiber, which Dr. Arjmandi said makes them exceptionally good at helping to keep the gastrointestinal (GI) system healthy. “Forgetting about the bones for a minute,” he said, “prunes are really great for digestive health. It’s something people may not want to hear about so much, but the truth is, the health of the entire body depends on the health of the GI system.” While drinking prune juice certainly can make the bowels move—quickly—Dr. Arjmandi said that eating dried prunes doesn’t have the same effect.

Prunes are chewy and sweet but not overwhelmingly sweet like dates, and they have an earthy tartness. Snack on them straight from the box…or chop them up and mix with nuts or add to salads. There are also some really tasty main courses, such as chicken Marbella, that are made with prunes… you can get some unique and delicious recipes by looking online at California Dried Plums.

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Source: Bahram H. Arjmandi, PhD, RD, Margaret A. Sitton Professor and chair, Nutrition, Food, and Exercise Sciences, College of Human Sciences, The Florida State University, Tallahassee, Florida.

Date: October 17, 2011 Publication: Bottom Line Health
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