Apples

Health Benefits
(Source: World's Healthiest Foods, George Mateljan)

Abundant Phytonutrients from Apples

Apples are so familiar to consumers that they are often not given their due in terms of the outstanding nourishment that they provide. And no apple nutrients stand out more prominently than its phenolic phytonutrients. We're talking about literally dozens of phenols and polyphenols that combine to give apples their renowned antioxidant capacity. To give you a better idea of just how extensive these apple phytonutrients are, we created the list below.

  • Anthocyanins (red varieties only)

    • cyanidin galactosides

    • cyaniding arabinosides

  • Dihydrochalcones

    • phloretin

    • phloridzin

  • Flavonols

    • catechins

    • epicatechins

    • procyanidins

  • Flavonols and flavonol glycosides

    • quercetin

    • isoquercetin

    • kaempferol

    • rutin

    • reinutrin

    • hyperoside

  • Hydroxycinnamic acid derivatives

    • caffeic acid

    • chlorogenic acid

    • coumaric acid

The phytonutrients listed above can be found in the skins (peels) of apples as well as their flesh (pulp). Many of these phytonutrients are 3–4 times more concentrated in the skin. However, since the physical amount of flesh in an average apple is much greater than the amount of skin, you can still get important phytonutrient benefits from the flesh. When you combine the availability of phenolic nutrients by consuming both peel and pulp, you can take advantage of nearly 90% of the total antioxidant capacity provided by apples. In terms of quantity, you can expect to get between 66–212 milligrams of total phenolic phytonutrients from about 1/2 (100 grams) of a medium fresh apple.

Cardiovascular Benefits from Apples

It is not surprising to see a combination of both animal and human studies showing cardiovascular benefits from consumption of this popular fruit. Most of the phenolic phytonutrients listed earlier in this section have been shown to function as antioxidants in the body and to provide antioxidant protection within blood vessels. In one recent study, consumption of one apple per day over a period of 4 weeks resulted in significantly decreased blood levels of oxidized LDL cholesterol. Additionally, this decrease in oxidized LDL was associated with a lowered risk of atherosclerosis.

Multiple animal studies on apple extracts have further linked apple consumption to decreased levels of LDL cholesterol overall (versus levels of oxidized LDL only). The mechanisms of action here are not entirely clear, but most researchers point to the ability of fiber-related components in apple to bind together with bile acids. When bound together with fiber-like components, bile acids can be more readily excreted from the body. Following their excretion, our cells will break apart some existing cholesterol into its bile acid components as a way to replace the bound bile acids that were excreted.

Total cholesterol and triglyceride levels in the blood have been shown to decrease in animal studies involving intake of apple extracts. Researchers have hypothesized a role not only for fiber-related apple components in this process, but for apple phytonutrients as well.

Also of interest in recent studies has been the potential role of gut bacteria in enhancing the cardiovascular support provided to us by apples. For example, studies show that certain forms of bile acids (called deconjugated bile acids) can act as signaling molecules which are able to bind onto cell nucleus receptors called farnesoid X receptors (FXRs) and inhibit synthesis of fat. These special forms of bile acids can be created by gut bacteria, provided that they have the right bile acids to work with. By binding together with bile acids higher up in the digestive tract, apple components may be able to help deliver these bile acids to the gut bacteria.

Other Potential Health Benefits from Apples

In our WHFoods rating system, apples rank as a good source of dietary fiber and provide about 4.4 grams of fiber per medium-sized apple. Pectin is the primary soluble fiber in apples, and it is a fiber with well-studied benefits for our digestive tract. Pectin is a soluble fiber that can help slow the pace of stomach emptying (also called gastric emptying) as well as the speed through which foods move along through the digestive tract (called transit time). As a consequence, the body is better able to stabilize blood sugar metabolism. Not only has apple pectin been studied in this regard, but its component parts—homogalacturonans and rhamnogalacturonans—have been studied as well. This relationship explains one of the key ways in which apple intake can help improve regulation of blood sugar.

Phloretin—one of the phenolic dihydrochalcones in apple—may also have an important role to play in the blood sugar-related benefits of apple consumption. In animal studies, phloretin obtain from apples has been shown to help stabilize blood glucose levels, plasma insulin levels, and lessen insulin resistance as measured by the homeostasis model assessment of insulin resistance (HOMA-IR). Eventually, we expect studies on humans enjoying apples in their weekly meal plan to show some of these same blood sugar-related benefits.

The potential role for apple intake in prevention of colon cancer is another area of strong research interest. Most of the studies to date have involved use of apple extracts in colon cancer cell lines in the laboratory or on rats or mice with experimentally induced cancers. Importantly, researchers already know that many different apple components can make their way through the human digestive tract and arrive at the very end region of our large intestine—namely, the colon. So this knowledge helps set the stage for future research in this key area.

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