The apple is the pomaceous fruit of the apple tree, species Malus domestica in the rose family Rosaceae. It is one of the most widely cultivated tree fruits. The tree is small and deciduous, reaching 3 to 12 metres (9.8 to 39 ft) tall, with a broad, often densely twiggy crown.[1] The leaves are alternately arranged simple ovals 5 to 12 cm long and 3–6 centimetres (1.2–2.4 in) broad on a 2 to 5 centimetres (0.79 to 2.0 in) petiole with an acute tip, serrated margin and a slightly downy underside. Blossoms are produced in spring simultaneously with the budding of the leaves. The flowers are white with a pink tinge that gradually fades, five petaled, and 2.5 to 3.5 centimetres (0.98 to 1.4 in) in diameter. The fruit matures in autumn, and is typically 5 to 9 centimetres (2.0 to 3.5 in) diameter. The center of the fruit contains five carpels arranged in a five-point star, each carpel containing one to three seeds.[1]
The tree originated from Central Asia, where its wild ancestor is still found today. There are more than 7,500 known cultivars of apples resulting in a range of desired characteristics. Cultivars vary in their yield and the ultimate size of the tree, even when grown on the same rootstock.[2]
At least 55 million tonnes of apples were grown worldwide in 2005, with a value of about $10 billion. China produced about 35% of this total.[3] The United States is the second leading producer, with more than 7.5% of the world production. Turkey, France, Italy, and Iran are also among the leading apple exporters.
The proverb "An apple a day keeps the doctor away," addressing the health effects of the fruit, dates from 19th century Wales.[44] Research suggests that apples may reduce the risk of colon cancer, prostate cancer and lung cancer.[45] Compared to many other fruits and vegetables, apples contain relatively low amounts of Vitamin C as well as several other antioxidant compounds.[36] The fiber content, while less than in most other fruits, helps regulate bowel movements and may thus reduce the risk of colon cancer. They may also help with heart disease,[46] weight loss,[46] and controlling cholesterol,[46] as they do not have any cholesterol, have fiber, which reduces cholesterol by preventing reabsorption, and are bulky for their caloric content like most fruits and vegetables.[46][47]
There is evidence that in vitro apples possess phenolic compounds which may be cancer-protective and demonstrate antioxidant activity.[48] The predominant phenolic phytochemicals in apples are quercetin, epicatechin, and procyanidin B2.[49]
Apple juice concentrate has been found to increase the production of the neurotransmitter acetylcholine in mice, providing a potential mechanism for the "prevent[ion of] the decline in cognitive performance that accompanies dietary and genetic deficiencies and aging." Others studies have shown an "alleviat[ion of] oxidative damage and cognitive decline" in mice after the administration of apple juice.[50]
The seeds are mildly poisonous, containing a small amount of amygdalin, a cyanogenic glycoside; usually not enough to be dangerous to humans, but it can deter birds.[51]
A recent study released by the FDA has stated that a chemical contained in the skin of most types of apples is now known to cause cancer in laboratory animals.[52]
