For nutritional reasons, we're often advised to consume the skins of fruits.
However, it's less often that research provides strong evidence in support of this advice. Recent studies have shown that the skin of pears contains at least three to four times as many phenolic phytonutrients as the flesh. These phytonutrients include antioxidant, anti-inflammatory flavonoids, and potentially anti-cancer phytonutrients like cinnamic acids. The skin of the pear has also been show to contain about half of the pear's total dietary fiber.
In recent studies measuring risk of type 2 diabetes in U.S. women, pears have earned very special recognition.
Researchers now know that certain flavonoids in food can improve insulin sensitivity, and of special interest in this area have been three groups of flavonoids (flavonols, flavan-3-ols, and anthocyanins). All pears contain flavonoids falling within the first two groups, and red-skinned pears contain anthocyanins as well. Intake of these flavonoid groups has been associated with decreased risk of type 2 diabetes in both women and men.
However, a new analysis of the Nurses' Health Study has shown that among all fruits and vegetables analyzed for their flavonoid content, the combination of apples/pears showed the most consistent ability to lower risk of type 2 diabetes. We believe that this special recognition given to pears as a fruit that can help lower risk of type 2 diabetes in women is likely to be followed by future studies showing this same benefit for men.
Decreased Risk of Type 2 Diabetes and Heart Disease
As a very good source of dietary fiber, pears might logically be expected to help protect us from development of type 2 diabetes (or DM2, which stands for "diabetes mellitus type 2) as well heart disease.
Adequate intake of dietary fiber is a long-established factor in reducing our risk of both diseases, and in the case of pears, this benefit may be even more pronounced due to the helpful combination of both soluble and insoluble fiber in this fruit. In addition to their fiber content, however, pears have other ways of helping to protect us against these diseases.
In the case of DM2, scientists now know that pear flavonols (including isorhamnetin, quercetin, and kaempferol), flavan-3-ols (especially epicatechin), and the anthocyanins (found in red-skinned varieties including Red Anjou, Red Bartlett, Comice, Seckel, and Starkrimson) all help improve insulin sensitivity. (More and more research attention is being given to mechanisms of action in this area, including regulation of the enzyme NADPH oxidase.)
In the case of heart disease, recent research has shown that pear fibers are able to bind together with bile acids in the intestine, lowering the pool of bile acids and decreasing the synthesis of cholesterol. In addition, the phytonutrients in pear may play a special role in these fiber-bile acid interactions.
The ability of pear fibers (and other fruit fibers) to bind bile acids has actually been compared to the cholesterol-lowering drug cholestyramine, with pears showing about 5% of the ability of the drug to accomplish this result. (Among commonly eaten fruits, only bananas and pineapples showed more bile acid-binding ability at 9% and 6%, respectively.)
Next Discussion: Can Hba1c go too low? »