Garlic and onions are in the same plant family and share numerous properties. The official name for garlic is Allium sativum L, whereas onions are known as Allium cepa L. Each has a long use as food and in traditional medicine, and these days you can find both plants in supplemental form, such as capsules or extracts, as well as on grocery store shelves. Always consult a health care provider before using a plant medicinally.
Active Components
The primary active compound in garlic is allicin, which gives the bulb its characteristic odor along with many of its healing benefits. Before garlic is crushed, it contains the odorless sulfur-containing chemical alliin, which converts to allicin upon crushing. Onions activate sulfur-containing compounds, mainly thiosulfinates including allicin, when they are processed, such as being minced or crushed via the enzyme alliinase. Onions also contain the flavonoid quercertin, which is found in a higher concentration in onions than any other fruit or vegetable.
Mechanism of Action
Allicin and other antioxidant compounds in garlic boost health by helping to neutralize free radicals. Free radicals damage your cells and are believed to contribute to numerous health conditions including heart disease and cancer, as well as the aging process, according to University of Maryland Medical Center. Antioxidants might prevent or reduce some of the damage by free radicals that is caused over time. Onions also boost health by helping to neutralize free radicals and contain flavonoids like quercertin that provide strong antioxidant action. Depending on the variety, onions also can contain the flavonoids kaempferol, found in leeks, and anthocyanins, found in red onions.
Garlic Research
Clinical research on garlic is promising in three main areas, according to University of Maryland Medical Center. The first is decreasing the progression of cardiovascular disease by helping reduce blood pressure and cholesterol. Garlic also strengthens the immune system, which might help your body fight off disease and protect against cancer. Garlic also might help prevent the onset of the common cold. Garlic also is being studied for properties that might help protect against parasites like roundworm; antiviral, antifungal and antibacterial uses; and combating fatigue.
Onion Research
The top uses for onions supported by clinical data are preventing appetite loss and age-related changes in your blood vessels, such as with potential cholesterol-lowering effects, according to the World Health Organization. Clinical studies also demonstrate possible antihyperglycaemic effects, which might help you manage diabetes, but more research is needed, according to WHO. Onion also has been studied for use as a diuretic, treating bacterial infections like dysentery, treating ulcers, as an asthma aid, and promoting healing of wounds.
References
- University of Maryland Medical Center: Garlic
- Health Canada: Garlic
- World Health Organization: Bulbus Allii Cepae Monograph
- "Onions and Other Vegetable Alliums"; James L. Brewster; 2008
- "Journal of Medicinal Food"; The antioxidant properties of garlic compounds: allyl cysteine, alliin, allicin, and allyl disulfide; L.Y. Chung; 2006
- "International Journal of Food Sciences and Nutrition"; Bioaccessibility of flavonoids and total phenolic content in onions and its relationship with antioxidant activity; s.M. Shim et al.; 2011
Member Comments