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Researchers con­duct­ing a promis­ing study in Canada pre­dicted that red onion extract will even­tu­ally be added to food prod­ucts and sold as a nat­ural can­cer pre­ven­ta­tive. According to the lead author Abdulmonem Murayyan, ​“We found onions are excel­lent at killing can­cer cells.”

Scientists know that a high con­sump­tion of onions is asso­ci­ated with a reduced risk of sev­eral types of can­cer. Moreover, as this veg­etable is a part of the Mediterranean diet (MedDiet), it may be par­tially respon­si­ble for the low inci­dence of the dis­ease in Southern Europe. Researchers Murayyan and Suresh Neethirajan at the University of Guelph wanted to ascer­tain which vari­ety of onions has the most anti­cancer prop­er­ties.

In the study pub­lished in the jour­nal Food Research International, they tested the effects of five kinds of onions on human colon can­cer cells and found Ruby Ring onions had the high­est effi­cacy in fight­ing the dis­ease.

“Our study con­firmed that red onion vari­eties are more potent in inhibit­ing can­cer cells than other onion vari­eties,” Suresh Neethirajan told Olive Oil Times. ​“They showed a 3.5- to 4‑fold increase in the num­ber of cells under­go­ing apop­to­sis (can­cer cell death), com­pared to the other types.”

What is so spe­cial about red onions? While all vari­eties of the veg­etable con­tain a high quan­tity of an anti­cancer flavonoid called quercetin, red onions are also rich in antho­cyanin, a com­pound that boosts the scav­eng­ing prop­er­ties of quercetin, explained Murayyan.

“Anthocyanin is instru­men­tal in pro­vid­ing color to fruits and veg­eta­bles, so it makes sense that the red onions, which are dark­est in color, would have the most can­cer-fight­ing power,” added Murayyan.

Neethirajan also shared how the health­ful com­pound in onions fights can­cer.

“Free rad­i­cals in the human sys­tem can lead to can­cer­ous cells that could develop into tumors, and they increase the risk of dia­betes or heart dis­ease if left unheeded,” he said.

“The quercetin mol­e­cules in onions attract and neu­tral­ize the free rad­i­cals. A hall­mark of can­cer cells is their abil­ity to avoid apop­to­sis. By trig­ger­ing apop­to­sis in abnor­mally divid­ing cells, can­cer cells and metas­ta­sis can be put in check. Onion-based flavonoids are best at trig­ger­ing apop­to­sis. Out of 28 veg­eta­bles and nine fruits, onions lead in quercetin con­tent.”

In addi­tion to the cur­rent dis­cov­ery, the researchers recently found onions were effec­tive at erad­i­cat­ing breast can­cer cells. Next, they plan to eval­u­ate the vegetable’s anti­cancer effects in human clin­i­cal tri­als.

Although it can be ben­e­fi­cial to put red onions in sal­ads and ham­burg­ers, the team believes onion extract will be added to food prod­ucts such as juice or baked goods in the future. They also antic­i­pate that it will be sold in pill form as a nutri­tional sup­ple­ment for fight­ing can­cer.

• Food Research International


• University of Guelph