Why You Should Always Choose Organic Red Onions

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Red and white onions have both been found to have antioxidant properties, but a new study suggests that the former variety may be more potent at fighting cancer cells. Canadian researchers found out that organic red onions produced from Ontario are more effective at killing colon and breast cancer cells than white onions and four other types of onions which include Lasalle, Fortress, Safrane, and Stanely. ^[1]

Onions are rich in quercetin, a type of flavonoid that has been found by researchers to help inhibit the growth of cancer cells. ^[2][3] The University of Guelph study tested five onion types grown in Ontario. It discovered the Ruby Ring onion variety as the most powerful in terms of promoting an unfavorable environment for cancer cells. Quercetin molecules are aided by another type of compound, anthocyanins, which stimulate the former’s scavenging properties.

Anthocyanins are naturally-occurring pigments that are responsible for the red, blue, purple, and black hues of many fruits and vegetables. ^[4] They are also considered to have powerful nutritional qualities. Richly colored fruits and vegetables have long been regarded as more nutritious, so it is not surprising that red onions have more cancer-fighting power than white.

The researchers produced quercetin extracts from the five onion varieties using a technique involving heated water in a pressurized container. They exposed the colon cancer cells to the extracts to determine their efficacy in inducing apoptosis, reducing the rate of proliferation, and slowing the migration of cancer cells into an exclusion zone.

The study did not utilize any toxic solvents or chemicals for the extraction of quercetin. Other methods use solvents which leave residues that are ingested in food, according to lead author Suresh Neethirajan who is an engineering professor at U of G. Their technique is important because it presents the potential of onion’s cancer-fighting compound in nutraceuticals and pill form. Neethirajan and colleagues published their findings in the journal Food Research International.

There is another study that correlates with the findings of the Guelph investigation. Published in the Journal of Agricultural and Food Chemistry, the 6-year study has also proven that organic red onions offer higher bioactive compound levels than conventionally grown ones. It found that total flavonoids were higher in red onions when grown under organic soil treatment. ^[5] The researchers also measured higher antioxidant activity in red onions than in conventional varieties.

These recent studies are two of the many that have shown the anti-carcinogenic potential of red onions and other varieties of the bulb. Scientists at Cornell University affirmed the higher anti-cancer chemical content of red onions. They identified shallots, a small elongated onion with reddish skin, as more effective against liver cancer cells than nine other onion varieties. ^[6]

Lab tests do not necessarily “translate” to how the onion will fare in actual human subjects. However back in 2006, a study presented data on the inverse relationship between the frequency of use of allium vegetables and the risk of several common cancers. The study focused on southern European populations. ^[7]

The chemopreventive activity of Allium vegetables such as onions and garlic was attributed by a 2004 study to their content of organosulphur compounds. This research first appeared in the British Journal of Cancer. ^[8]