Apples ( MALUS sp., Rosaceae) are a rich source of nutrient as well as non-nutrient components and contain high levels of
polyphenols and other
phytochemicals. Main structural classes of apple constituents include
hydroxycinnamic acids, dihydrochalcones,
flavonols (
quercetin glycosides), catechins and oligomeric
procyanidins, as well as
triterpenoids in apple peel and
anthocyanins in red apples. Several lines of evidence suggest that apples and apple products possess a wide range of
biological activities which may contribute to health beneficial effects against
cardiovascular disease,
asthma and pulmonary dysfunction, diabetes,
obesity, and
cancer (reviewed by Boyer and Liu, Nutr J 2004). The present review will summarize the current knowledge on potential
cancer preventive effects of apples, apple juice and apple extracts (jointly designated as apple products). In brief, apple extracts and components, especially oligomeric
procyanidins, have been shown to influence multiple mechanisms relevant for
cancer prevention in IN VITRO studies. These include antimutagenic activity, modulation of
carcinogen metabolism,
antioxidant activity, anti-inflammatory mechanisms, modulation of signal transduction pathways, antiproliferative and apoptosis-inducing activity, as well as novel mechanisms on epigenetic events and innate immunity. Apple products have been shown to prevent skin, mammary and colon
carcinogenesis in animal models. Epidemiological observations indicate that regular consumption of one or more apples a day may reduce the risk for lung and
colon cancer.