Health & Wellbeing

Onions and Garlic: 2 Veggies That Can Help Prevent Cancer

Natalia J.

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We have written time and again about types of foods one should avoid to prevent cancer, with processed and red meat, alcohol, and even fruit juices being among the worst offenders. But are there any specific food recommendations for those who want to prevent cancer beyond the usual tips like “eat more fiber” or “eat more fruit and vegetables”? Tomatoes are one possible addition, but there’s a catch, so we recommend reading our article about tomatoes and cancer prevention here. Other recommendations, those we’ll focus on in this article, are onions and garlic, that have been time and time again associated with cancer-fighting properties.

onions and garlic prevent cancer selection of onions and garlic

More specifically, these pungent veggies have been shown to prevent breast cancer and colorectal cancer, as well as prostate and stomach cancer. The strongest and latest evidence is in relation to colorectal and breast cancer. At the beginning of 2019, one study at the First Hospital of China Medical University has shown that the two vegetables seemed to contribute to the prevention of colorectal cancer, one of the top five most widespread cancers.

The researchers concluded that the more onions and garlic you eat, the better the protective effects. The authors matched 833 participants with colorectal cancer with an equal number of control subjects matched by age, sex, and area of residence, and found a 79% decrease in colorectal cancer recurrence in the group of subjects who ate the most onions and garlic.

A more recent article researching breast cancer in women in Puerto Rico also found that high onion and garlic consumption seems to lower one’s risk of breast cancer. Similarly to the Chinese study, the Puerto Rican research matched 314 women aged 30-79 with a history of breast cancer between 2008 and 2014 demographically to an equal number of control subjects.

The study reported a 67% lower breast cancer risk in the group of participants who had the highest sofrito intake, which is a popular Puerto Rican condiment consisting predominantly of onions and garlic.

onions and garlic prevent cancer green onions

Understandably, this last study had some limitations, as the authors point out themselves, "Although the recipe for sofrito varies to some extent, other ingredients, such as bell peppers, tomatoes, cilantro, and black pepper are usually added. Since we did not adjust our models for these ingredients, we cannot be sure that our results were due to the sole effect of onions and garlic."

Still, the cancer hindering effects of onions and garlic are becoming increasingly robust, and scientists may have even discovered why. The compounds associated with cancer-fighting properties of onions and garlic, also known as allium vegetables in medical terminology, are flavanols and organosulfur compounds. These two groups of chemicals naturally occurring in onions, garlic, spring onions, and leeks have been found both epidemiologically and in a lab, setting to hinder the development of several types of cancer cells, and so consuming these vegetables in high quantities is beneficial.

Needless to say, the consumption of healthy foods like these and others alone will not prevent cancer on its own, you also need to avoid high-risk foods, as well as stay active and stress-free, not to mention undergo preventative medical examinations on a regular basis.