Apples are known as Malus domestica. They belong to the Rosacea or Rose family, which also includes apricots, plums, peaches, and almonds. Common varieties of apples include Fuji, Gala, Golden Delicious, Granny Smith, McIntosh, Pink Lady, and Red Delicious, among others. Apples are an important contribution to the diet by providing fiber, potassium, vitamins A and C, and other nutrients (Savatovic et al., 2008). They can be eaten raw, cooked, or dried, or in a processed form like compote, jam, juice, marmalade, or sauce. In 2012, around 70 million tons of apples were consumed globally (Szakiel, Paczkowski, Pensec, & Bertsch, 2012).
There are over 7,000 varieties of apples, all believed to have originated from the wild apple Malus silvestri, found in Central Asia. The apple was domesticated and grown in Asia and Europe, and brought to the American and Australian continents by European colonists. The Granny Smith apple originated in Australia in 1868 when a lady named Maria Smith propagated the seedling (Savatovic et al., 2008).
Apples and apple products, such as juices and apple extracts, have a high content of phytochemicals. Phytochemicals are plant-derived compounds or biologically active components in plants believed to offer protection from diseases (Heneman & Zidenberg-Cherr, 2008). Some of the most commonly found phytochemicals in apples are flavonoids, including the flavonol quercetin (Heneman & Zidenber-Cherr, 2008), and phenolic acids (Boyer & Liu, 2004). In the standard diet in the United States (US), apples are the source of 22% of phenolics consumed (Boyer & Liu, 2004). Apple consumption has increased antioxidant enzyme levels, and plasma antioxidant activity (Hyson, 2011). They affect health by reducing rates of cancer, asthma, cardiovascular disease, hypercholesteremia, and type 2 diabetes (Boyer & Liu, 2004).
In in vitro studies, apple extracts reduced the size of colon cancer cells. Some of the cancer cells were inhibited with an apple extract at a concentration of 70 mg / mL (Jaganathan et al., 2014). Rats that were fed apple juice experienced a decrease in proliferation of colon cancer, and had a 50% lower occurrence of cancer cells, despite being injected with a carcinogenic substance (Jaganathan et al., 2014).
Apples are thought to increase lifespan and quality of health. A study conducted on nematodes, Caenorhabditis elegans, indicated that nematodes that were administered apple extracts lived up to 39% longer, had increased motility, produced fewer byproducts of the aging process, and were more resistant to stress (extreme heat and UV radiation) than nematodes that did not get apple extracts (Vayndorf, Lee, & Liu, 2013).
Studies conducted on humans demonstrated that apples have a significant impact on health. In a study conducted in Italy in 2005, over 6,000 patients consuming one apple a day saw reduced risk of several types of cancers, including breast, colorectal, esophageal, larynx, oral, ovary, pharynx, and prostate cancers (Hyson, 2011). A study conducted in 2007 included 478,590 participants in 10 European countries, and found that those who consumed at least one apple or pear a day had a lower incidence of lung cancer among smokers and non-smokers (Hyson, 2011). In addition, a group of Finnish women who consumed an apple per day saw 43% reduction of mortality rates due to coronary disease, and men saw a 19% reduction of mortality rates from coronary disease (Hyson, 2011). Apple consumers saw a reduced risk of type 2 diabetes and higher weight loss than those who did not consume apples regularly (Hyson, 2011).
It is believed that apple peels offer more bioactive phytochemicals than the flesh of the apple. Studies have found that peels contain a higher amount of triterpenoids, such as ursolic acid, when compared to apple flesh. Triterpenoids have shown antitumor activity and are beneficial in the treatment of many types of cancers. Although it is unlikely that apple peel will be consumed on its own, evidence shows that consuming the whole apple, including flesh and peel, gives the maximum nutritious value (Szakiel et al., 2012).
Apple juice is also beneficial. In a study including 2,600 children in the United Kingdom, those who drank one serving of apple juice per day had reduced wheezing. Also, mothers who drank apple juice during pregnancy had children with reduced incidences of asthma (Hyson, 2011).
Several studies indicated that consuming one or more medium sized apples per day (weighing roughly 150 grams) has marked health benefits (Boyer & Liu, 2004). The suggested consumption of apple juice is around 160 ml per day (Hyson, 2011).
Apples can be stored for a relatively long period, particularly if they are kept in cold storage or refrigeration. An apple can last for up to 6-months (Tarozzi, Marchesi, Cantelli-Forti, & Hrelia, 2004). However, some of the nutritional value of the apple decreases with time. A study showed that the maximum phenolic and antioxidant activity occured when the apple were freshly picked. After three months, phenolic compounds and antioxidant activity decreased in the apple peel, but not in the apple flesh. After six months, phenolic compounds and antioxidant activity further decreased in peel, and also decreased in the flesh (Tarozzi et al., 2004).
The adage that an apple a day keeps the doctor away has some truth to it. Consuming apples and apple products has health benefits.
Boyer, J., & Liu, R. H. (2004). Apple phytochemicals and their health benefits. Nutritional Journal, 3(5), 1-15. Retrieved from http://www.nutritionj.com/content/3/1/5
Heneman, K. & Zidenberg-Cherr, S. (2008). Some facts about phytochemicals. Nutrition and Health Info-Sheet For Health Professionals. Retrieved on February 14, 2015 from http://nutrition.ucdavis.edu/content/infosheets/fact-pro-phytochemical.pdf
Hyson, D. A. (2011). A comprehensive review of apples and apple components and their relationship to human health. Advances in Nutrition, An International Review Journal, 2, 408-420. doi:10.3945/an.111.000513
Jaganathan, S. K., Vellayappan, M. V., Narasimhan, G., Supriyanto, E., Dewi, D. E. O., Narayanan, A. L. T., Balaji, A., Subramanian, A. P., & Yusof, M. (2014). Chemopreventive effect of apple and berry fruits against colon cancer. World Journal of Gastroenterology, 20(45), 17029-17036. doi:10.3748/wjg.v20.i45.17029
Savatovic, S. M., Cetkovic, G. S., Dilas, S. M., Tumbas, V. T., Canadanovic-Brunet, J. M., Cetojevic-Simin, D. D., & Mandic, A. I. (2008). Antioxidant and antiproliferative activity of granny smith apple pomace. APTEFF, 39(1), 201-212. doi:10.2298/APT0839201S
Szakiel, A., Paczkowski, C., Pensec, F., Bertsch, C. (2012). Fruit cuticular waxes as a source of biologically active triterpenoids. Phytochemical Review, 11, 263-284. doi:10.1007/s11101-012-9241-9
Tarrozzi, A., Marchesi, A., Cantelli-Forti, G., & Hrelia, P. (2004). Cold-storage affects antioxidant properties of applies in Caco-2 cells. The Journal of Nutrition, 134(5), 1105-1109. Retrieved from http://jn.nutrition.org/content/134/5/1105.full.pdf+html
Vayndorf, E. M., Lee, S. S., & Liu, R. H. (2013). Whole apple extracts increase lifespan, healthspan and resistance to stress in Caenorhabditis elegans. Journal of Functional Foods, 5(3), 1236-1243. doi:10.1016/j.jff.2013.04.006