The following information is directly pulled from the National Institutes of Health database. The National Institutes of Health (NIH) is a biomedical research facility primarily located in Bethesda, Maryland. An agency of the United States Department of Health and Human Services, it is the primary agency of the United States government responsible for biomedical and health-related research.
Onions–a global benefit to health
Onion (Allium cepa L.) is botanically included in the Liliaceae and species are found across a wide range of latitudes and altitudes in Europe, Asia, N. America and Africa. World onion production has increased by at least 25% over the past 10 years with current production being around 44 million tonnes making it the second most important horticultural crop after tomatoes. Because of their storage characteristics and durability for shipping, onions have always been traded more widely than most vegetables. Onions are versatile and are often used as an ingredient in many dishes and are accepted by almost all traditions and cultures. Onion consumption is increasing significantly, particularly in the USA and this is partly because of heavy promotion that links flavour and health. Onions are rich in two chemical groups that have perceived benefits to human health. These are the flavonoids and the alk(en)yl cysteine sulphoxides (ACSOs). Two flavonoid subgroups are found in onion, the anthocyanins, which impart a red/purple colour to some varieties and flavanols such as quercetin and its derivatives responsible for the yellow and brown skins of many other varieties. The ACSOs are the flavour precursors, which, when cleaved by the enzyme alliinase, generate the characteristic odour and taste of onion. The downstream products are a complex mixture of compounds which include thiosulphinates, thiosulphonates, mono-, di- and tri-sulphides. Compounds from onion have been reported to have a range of health benefits which include anticarcinogenic properties, antiplatelet activity, antithrombotic activity, antiasthmatic and antibiotic effects. Here we review the agronomy of the onion crop, the biochemistry of the health compounds and report on recent clinical data obtained using extracts from this species. Where appropriate we have compared the data with that obtained from garlic (Allium sativum L.) for which more information is widely available. Read More.
Onion: nature protection against physiological threats
Onion (Allium cepa L.) is found in various regions of Europe, North America, Asia, and Africa. It is one of the classic examples of Allium species used not only for culinary preparations but also for medicinal purposes. Onion with a variety of purposes is often used as a raw material in many dishes and accepts almost all of the traditions and culture. Owing to its storage characteristics and durability of shipping, onions have been traded more widely than most vegetables. The pungent fractions of garlic are mostly sulfur-containing moieties while its two chemical groups have marked effect on human health. These are flavonoids and ALK (EN)-based cysteine sulfoxides (ACSOs). Compounds in onions have been reported with a range of health benefits, including anticancer properties, antiplatelet activity, antithrombotic activity, antiasthmatic activity, and antibiotic effects. Read More.
Allium cepa; functional benefits; health promoting potential; nutritional benefits; physicochemical characteristics
Garlic and onions: Their cancer prevention properties
The Allium genus includes garlic, onions, shallots, leeks, and chives. These vegetables are popular in cuisines worldwide and are valued for their potential medicinal properties. Epidemiological studies, while limited in their abilities to assess Allium consumption, indicate some associations of Allium vegetable consumption with decreased risk of cancer, particularly cancers of the gastrointestinal tract. Limited intervention studies have been conducted to support these associations. The majority of supportive evidence on Allium vegetables cancer preventive effects comes from mechanistic studies. These studies highlight potential mechanisms of individual sulfur-containing compounds and of various preparations and extracts of these vegetables, including decreased bioactivation of carcinogens, antimicrobial activities, and redox modification. Allium vegetables and their components have effects at each stage of carcinogenesis and affect many biological processes that modify cancer risk. This review discusses the cancer preventive effects of Allium vegetables, particularly garlic and onions, and their bioactive sulfur compounds and highlights research gaps.
Keywords: garlic, onion, cancer prevention, Allium
Altering dietary habits may be a practical and cost-effective means of reducing cancer risk and modifying tumor behavior. Approximately 30–40% of cancers are preventable by appropriate food and nutrition, physical activity, and maintenance of healthy body weight (1). This means choosing foods that help to maintain a healthy body weight, reducing consumption of foods such as red or processed meats that may increase cancer risk, and increasing consumption of foods that may decrease cancer risk, including foods of plant origin (1). There is an increasing public health demand to identify those dietary patterns, bioactive foods, and components that may decrease cancer risk. One particular group of foods that has raised considerable interest for their putative cancer preventive properties is the Allium genus.
Allium is the Latin word for garlic. It is part of a monocot genus of flowering plants frequently referred to as the onion genus. The genus includes approximately 500 species (2), including edible onions (A. cepa), garlics (A. sativum), shallots (A. ascalonicum), chives (A. schoenoprasum), and leeks (A. porrum). Garlic and onions are originally native to central Asia and are among the oldest cultivated plants in the world (2). Garlic’s edible bulbs are an important culinary spice and constituent of traditional Chinese medicine. The bulbs and leaves of onions have a wide variety of flavors and textures, and therefore many culinary uses. Shallots, which are closely related to onions, are characterized by their less pungent onion flavor and are commonly used in cooked dishes or are pickled. Chives are distinguished by their edible green scapes with mild onion flavor. Leeks have edible leaf sheaths with mild onion flavor. All of these vegetables have been valued in many cultures for their pungent flavors and culinary uses and for their health benefits for over 4000 years (3, 4). Ancient medical texts from Egypt, Greece, Rome, China, and India cite therapeutic applications for Allium vegetables (2). An Egyptian medical papyrus, The Codex Ebers (~1550 B.C.), lists 22 preparations in which garlic was added. Hippocrates advocated garlic as a laxative and a diuretic, and Aristophanes and Galenal suggested garlic for the treatment of uterine tumors. Furthermore, several medicinal uses for both garlic and onion were cited by the Roman naturalist Pliny the Elder in his Historia naturalis.