Allium cepa (Onion)

Chapter 62 Allium cepa (Onion)

Allium cepa (family: Amaryllidaceous or Liliaceous)

Common name: onion

image History and Folk Use

Although not as valued a medicinal agent as garlic, onion has been used almost as widely. Like garlic (Allium sativum), onion has been used as an antispasmodic, carminative, diuretic, expectorant, stomachic, anthelmintic, and anti-infective agent. Externally, it has been used as a rubefacient and poultice, giving relief for skin diseases and insect bites.13

Onions originated in the central part of Asia, from Iran to Pakistan, and northward into the southern part of Russia. Onions have been revered throughout time not only for their culinary use but also for their therapeutic properties. As early as the sixth century, onions were used as medicine in India. Although they were popular with the ancient Greeks and Romans, they were often dressed with extra seasonings, because many people did not find them spicy enough. Yet it was their pungency that made onions popular among poor people throughout the world, because this inexpensive vegetable could spark up meals. Onions were an indispensable vegetable in the cuisines of many European countries during the Middle Ages and later even served as a classic healthy breakfast food. Christopher Columbus brought onions to the West Indies, and then their cultivation spread throughout the Western hemisphere. Today, China, India, the United States, Russia, and Spain are among the leading producers of onions.

World onion production has increased dramatically, with current production around 44 million tons per year, making onions 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, often used in many dishes, and accepted by almost all traditions and cultures.4

image Pharmacology

Onions and garlic, due to their similar constituents, have many of the same pharmacologic effects. However, significant differences make one more advantageous than the other in certain conditions.

One of the key nutritional qualities of onions is their high content of quercetin. To determine uptake as well as in vivo antioxidant effects of quercetin from onions, six healthy nonobese, normocholesterolemic female volunteers participated in a randomized two-phase crossover supplementation trial to compare the antioxidant effects associated with (1) a meal of fried onions and (2) a meal of fried onions and fresh cherry tomatoes.5 Plasma flavonoids, lymphocyte DNA damage, plasma ascorbic acid, tocopherols and carotenoids, urinary malondialdehyde, and 8-hydroxy-2-deoxyguanosine were determined to assess flavonoid absorption and antioxidant efficacy. The results indicated that the flavonoid glucosides (quercetin-3-glucoside and isorhamnetin-4-glucoside) were significantly elevated in plasma after ingestion of the onion meal, and the increases were associated with an increased resistance of lymphocyte DNA to DNA strand breakage.

A significant decrease in the level of urinary 8-hydroxy-2-deoxyguanosine was evident 4 hours after ingestion of the onion meal. After the combined tomato and onion meal, only quercetin was detected in plasma. Endogenous base oxidation was decreased, but resistance to strand breakage was unchanged. No significant change in the excretion of urinary malondialdehyde occurred after either meal. The conclusions from the study were that both meals—onions and onions with tomatoes—led to transient decreases in biomarkers of oxidative stress, although the particular biomarkers affected differed. It is possible that the differences in patterns of response reflect the different uptakes of flavonoids, but the underlying mechanism is not yet understood.

Antimicrobial Activity

Although onions exhibit antibacterial, antifungal, and anthelmintic activity, it is not nearly as potent as that of garlic. This suggests that garlic may be better indicated in cases of infection,2,3,6 but onion can usually be consumed in larger quantities than garlic, which may increase the concentration of antimicrobial constituents in vivo to approximate those of garlic.

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Sep 12, 2016 | Posted by in MANUAL THERAPIST | Comments Off on Allium cepa (Onion)
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