Do Apples Yield a Bountiful Harvest of Health Benefits?

What associations do apples call to mind for you? Do you hear the 1968 Roger Miller hit, “Little Green Apples,” written by Bobby Russell? Do you smell a freshly baked pie from grandmother’s kitchen? Do you think of brain health and antihistamine? Or do you reflect on a variant of the 1866 Welsh maxim, “Eat an apple on going to bed, and you’ll keep the doctor from earning his bread”?

Most apples are consumed as fresh fruit, which equates to U.S. per capita consumption of slightly more than 15 pounds annually. A recent report suggests that daily apple eaters (approximately 9% of the study population of U.S. adults) tended to follow a more healthful lifestyle and avoid medications; however, the number of overnight hospital, physician, and mental health visits did not differ from that of non-eaters of apples (approximately 91% of the study population) (Davis et al. 2015). According to 2003–2010 NHANES data, about 26% of the U.S. population consumes some form of apple products, such as whole apples, apple sauce, and 100% apple juice. Importantly, these data indicate that those who consume these products, including children, typically adhere to a healthier dietary pattern and present lower BMIs versus non-consumers of apple products (O’Neil et al. 2015).  

The global market for apples and apple products demoted the United States as a world leader in apple production and export, and has transformed countries like China and Poland to the forefront of apple export (Fresh Plaza 2014). Still, however, the U.S. market is sizable: about $14 billion at retail, according to the U.S. Apple Association.

A typical fresh, whole apple is about 85% water, 13% carbohydrate, and approximately 4% vitamins and minerals. A medium-sized apple provides almost 100 kcal of energy. U.S. apple growers continue to support important scientific and consumer research, including major projects to assess the role of apples in weight management in children and in reducing the risk of type 2 diabetes among Baby Boomers.

The scientific literature is replete with information on the genetics of apple cultivars and their potential positive impact on health. In addition to functioning as “nature’s toothbrush,” apples contain phytochemicals, which are associated with their health benefits. The phytochemical composition of apples varies among cultivars, throughout the natural ripening of the fruit, and according to their subsequent utilization in a variety of food products (Thompson-Witrick et al. 2014; Kahle et al. 2005; Boyer and Liu 2004). Some of the flavonoids in apples and apple-based products include an array of quercetin glycosides or aglycones (flavanols), catechins (flavan-3-ols), and caffeic acid and chlorogenic acid (hydroxycinnamic acids).

Limited evidence suggests dietary quercetin glycosides, primarily found in the apple peel (van der Sluis et al. 2001) may function to reduce the risk of cardiovascular disease (Gormaz et al. 2015) and some forms of epithelial inflammation (Dower et al. 2015) and may impede angiogenesis associated with cancer (Ravishankar et al. 2015) while possibly improving brain health (Bouayed et al. 2007). However, a recent report evaluated cardiovascular disease among Swedish women adhering to a Nordic diet that includes rye bread, oatmeal, apples/pears, cabbages, root vegetables, and fish/shellfish. This survey, which included more than 40,000 participants, indicated an absence of a significant association with apples/pears per se as a component of the Healthy Nordic Food Index score and the risk of cardiovascular disease (Roswall et al. 2015). On the other hand, a 2007 report on more than 34,000 postmenopausal women contributed to the American Heart Association’s recommendation for increased fruit consumption, including flavonols (e.g., quercetin) from apples, broccoli, and onions, to reduce the risk of heart disease (Mink et al. 2007). The daily flavonoid intake for the women in the study ranged from about 96 mg to slightly more than 600 mg.

From a practical perspective, these studies suggest that one needs to consume approximately 10 apples (>150 mg/day quercetin glycosides) daily to limit the progression or onset of the previously mentioned conditions. The bioavailability of flavanols as pure substances or within a meal is quite variable, yet the typical value is < 1%–7% of the dose (Manach et al. 2005). Limited evidence suggests pectin, a dominant fiber in apples, may enhance the absorption of these phenolics (Nishijima et al. 2015; Wojdylo et al. 2008).

Apples, like most fruits and vegetables, contain a broad spectrum of substances that number in the thousands. Our understanding of the chemical nature of these substances and their bioavailability and metabolism as well as their interactions is limited. While an apple a day may not keep the doctor away, their regular consumption may certainly be an important component of a healthful dietary pattern (Hyson 2011).

Roger Clemens, DrPH, CFS, Contributing Editor
Adjunct Professor, Univ. of Southern California School of Pharmacy, Los Angeles, Calif.
[email protected]