What would the art of cooking be without onions? These pungent members of the Allium family are integral in creating the base flavors of many soups, sauces and stews. Red onions in particular, with their sweet and tangy flavor, can liven up a salad like nothing else.
Along with their vast culinary significance, onions have been scientifically found to have potent qualities that help protect the body from cancer. While all onions work to serve this important purpose to varying degrees, red onions contain additional cancer-fighting compounds, which also give them their vibrant color.
Researchers have long known that onions have a noteworthy role to play in cancer prevention. Part of their anticarcinogenic nature stems from their organosulfur content. Sulfur is a very important mineral to the human body; it supports optimal cardiovascular function, as well as optimal nervous system and muscular health.
Natural sulfur compounds, such as those found in onions, have also been found to have strong antioxidant properties that help prevent both cancer and liver damage
A 1988 study, published in the journal Carcinogenesis, tested eight organosulfur compounds derived from both onions and garlic.
The authors of the study concluded, “in evaluating relationships between diet and cancer, it would be useful to consider the possible role of garlic and onion organosulfur compounds as protective agents.”
Another study, performed in 2001 and published in the journal Nutrition and Cancer, declares, “there is evidence that onions and garlic protect against cancer in humans. It has been suggested that this effect is due to the organosulfur compounds in these vegetables and that these substances act through induction of phase II detoxification enzymes.”
Flavonoids, another group of antioxidants contained in onions, also contribute significantly to their anticarcinogenic effects. These types of antioxidants, also called flavonoid glycosides, have been found to help boost the immune system and strengthen capillaries, along with protecting against many cancers.
Dr. Rui Hai Liu, an associate professor of food science at Cornell University, states,
“onions are one of the richest sources of flavonoids in the human diet. And flavonoid
consumption has been associated with a reduced risk of cancer, heart disease and
diabetes. Flavonoids are not only anti-cancer but also are known to be anti-bacterial,
anti-viral, anti-allergenic and anti-inflammatory.”
A 2005 study published in the Journal of Agricultural and Food Chemistry found seven different flavonoids in southern Italian red onions. One of the flavonoid types found in the highest concentration was quercetin.
Quercetin, along with being linked to reducing the risk of heart disease and alleviating symptoms of allergies, prostatitis and inflammatory conditions such as rheumatoid arthritis, has also been found to inhibit the growth of breast, colon, endometrial, lung and prostate cancers.
Along with the rich anticarcinogenic benefits of other onions, red onions contain anthocyanins, a group of flavonoid antioxidants that gives them their purple-red pigment. Anthocyanins have been associated with heart health, improved cognitive function, longevity and protection from cancer. They are also linked to healthy eyesight, alleviation of allergy symptoms and guarding the stomach lining from damage.
It is important to note that much of the antioxidant content of red onions is found in the outer layers very near the peel. Because of this, it is crucial to peel the onion as little as possible to keep the maximum amount of these valuable compounds.
It is ideal to eat red onions raw. However, if you choose to cook them, let them sit for 10 or 15 minutes after slicing before you cook, in order to release more sulfur compounds and encourage heat resistance. When cooking, low and slow is best to maintain maximum quercetin content.
There are a virtually endless number of ways to incorporate red onions – both raw and cooked – into recipes. One delicious raw preparation is to simply slice them, add them to your favorite raw, leafy greens (such as arugula or spinach), and dress with extra virgin olive oil, sea salt and a splash of fresh lime juice.
However you choose to eat them, making red onions an everyday part of your healthy meals may do wonders for your health, and might even help you to avoid the scourge of cancer.
Sources:
http://www.sciencedirect.com/science/article/pii/S0308814606006005
http://pubs.acs.org/doi/abs/10.1021/jf048152r
http://www.ncbi.nlm.nih.gov/pubmed/11962257
http://carcin.oxfordjournals.org/content/9/1/131
http://www.whfoods.com/genpage.php?tname=foodspice&dbid=45
http://www.news.cornell.edu/stories/2004/10/some-onions-have-excellent-anti-cancer-benefits
http://www.wisegeek.com/what-are-flavonoid-glycosides.htm
http://www.marksdailyapple.com/why-you-should-eat-sulfur-rich-vegetables/#axzz2zJ1o6wMN
http://umm.edu/health/medical/altmed/supplement/quercetin
http://www.chiro.org/nutrition/FULL/Anthocyanins.shtml
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