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Researchers extract cancer-fighting properties from Ontario grown onions

New research at the University of Guelph has found a way to safely extract the free-radical fighting properties of Ontario-grown onions, creating new opportunities for Ontario farmers and the nutraceutical and food production industries.

In the not-so-distant future, you could be enjoying the healthy properties of onions through supplements, additives and creams.

Scientist have long known that onions carry the highest content of quercetin (an antioxidant flavonoid) of nearly 40 different fruits and vegetables. Flavonoids like quercetin attract and neutralize free radicals – the naturally-occurring molecules in human tissue that can lead to cancerous cells.

Suresh Neethirajan, a bioengineering researcher in the School of Engineering at the University of Guelph, is in the final phase of an Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) funded project examining the varying levels of quercetin in Ontario-grown onions.

“This is the first study that’s looked specifically at the 17 or 18 major varieties of onions grown in Ontario to determine if the level of flavonoids varies among varieties,” says Neethirajan.

After extracting flavonoids from the Ontario onion varieties using a new water-based extraction technology developed in Neethirajan’s lab, there was a clear winner.

“We put the onion flavonoids in direct contact with human breast and colon cancer cells, and measured the rate of apoptosis (cancer cell death) among the different varieties. Red onions have a four-fold increase in the ability to trigger cancer cell death compared to any other variety,” he says.

For Ontario onion growers, the news gets even better.

“Onions grown in Ontario, especially in the Holland Marsh, are able to retain more nutrients and antioxidants,” Neethirajan says, attributing this largely to good management practices and soil type.

With the strong demand for antioxidant nutraceuticals, Neethirajan sees potential for a new high-value crop potential for farmers and a residue-free, onion-based antioxidant for manufacturers.

“We want farmers to know what manufacturers might be looking for, so they can be ready with sufficient supply,” he says.

The extraction process removes most of the onion smell and taste, opening options for adding the substance to drinks, bakery items, encapsulating in a pill form, and even skin-based products.

“Now that we have developed a new, safer protocol for extracting flavonoids from onions, and scientifically verified the activity on breast and colon cancer cells, the next step is to look at economical ways to produce and manufacture products with onion-extracted flavonoids,” he says.

And if you’re wondering if you could just add more raw onion to your diet for the same healthful effect, it’s not that simple.

Neethirajan says you’d need to eat a few kilograms of raw onion a day to realize the potential cancer-fighting effects from onion flavonoids, compared to levels concentrated through the extraction process.

Photo source: S. Neethirajan, University of Guelph

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