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, and the most widely known of the many members of genus Malus that are used by humans.
Health benefits: The proverb "An apple a day keeps the doctor away.", addressing the health effects of the fruit, dates from the 19th century Wales. Research suggests that apples may reduce the risk of colon cancer, prostate cancer and lung cancer.
Compared to many other fruits and vegetables, apples contain relatively low amounts of vitamin C, but are a rich source of other antioxidant compounds. 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, weight loss, and controlling cholesterol. The fiber contained in apples reduces cholesterol by preventing reabsorption, and (like most fruits and vegetables) they are bulky for their caloric content.
There is evidence that in vitro apples possess phenolic compounds which may be cancer-protective and demonstrate antioxidant activity. The predominant phenolic phytochemicals in apples are quercetin, epicatechin, and procyanidin B2.
Apple juice concentrate has been found to increase the production of the neurotransmitter acetylcholine in mice, providing a potential mechanism for the "prevention of the decline in cognitive performance that accompanies dietary and genetic deficiencies and aging." Other studies have shown an "alleviat[ion of] oxidative damage and cognitive decline" in mice after the administration of apple juice.
However, apple seeds are mildly poisonous, containing a small amount of amygdalin, a cyanogenic glycoside; it usually is not enough to be dangerous to humans, but can deter birds.