Red onions add color and zest to many dishes. Being low in calories and carbohydrates, as well as fat-free, they are also diet-friendly. Though all onions contain healthy compounds called flavonoids, red onions have the highest concentration of them, as reported in the December 12, 2007 issue of "Journal of Agricultural and Food Chemistry."
Red onions contain a compound called quercetin, which helps give them their deep color. Quercetin also delivers several health benefits, one of which is its anti-cancer properties, according to the University of Maryland Medical Center. Quercetin is an antioxidant which has been shown to halt cancer cells from growing and multiplying, as well as initiate the spontaneous death of cancer cells. UMMC reports that quercetin in lab and animal studies showed inhibitory success against lung, breast, prostate, ovarian, colon and endometrial cancers.
Lower Blood Pressure
The quercetin in red onions not only prevents cancer, it also lowers your blood pressure. High blood pressure puts you at risk for kidney disease, heart disease and stroke. Tossing red onions in your salad or adding them to a sandwich helps you lower your risk of hypertension. Researchers stated that quercetin effectively lowers blood pressure and that a diet rich in quercetin containing fruits and vegetables will help prevent the negative health consequences associated with hypertension, according to results published in the January 2009 issue of "Pharmacological Reports."
Lower Blood Sugar
High blood sugar has dire consequences for your overall health. The Centers for Disease Control explains that high blood sugar negatively affects everything from your dental health to your heart, kidneys and nerve endings. A diet that includes red onions can help lower your risk of developing diabetes. Researchers in Sudan studied the effects of raw, red onion on type 1 and type 2 diabetic patients. In both groups the consumption of red onion significantly lowered blood sugar levels. In some cases, the addition of red onion to the diet enabled patients to reduce their antidiabetic medication. The researchers concluded that red onion could be used as a dietary means of controlling blood sugar, according to the October 14, 2010 issue of "Environmental Health Insights."
When tested alongside garlic and white onions, red onions were found to be the most effective at helping to lower cholesterol levels. A study published in the May 2010 issue of "Phytotherapy Research" found that when pigs were fed high-cholesterol diets supplemented with garlic and onions, the group fed the raw red onions did not experience a rise in total cholesterol levels. This result was also true of pigs fed red onions that had been blanched for 90 seconds. The study concluded that blanching red onions may help preserve their health-promoting compounds.
- Journal of Agricultural and Food Chemistry: Onions: A Source of Unique Dietary Flavonoids
- University of Maryland Medical Center: Quercetin
- Pharmacological Reports: Antihypertensive Effects of the Flavonoid Quercetin
- Centers for Disease Control and Prevention: Diabetes Health Concerns
- Environmental Health Insights: Preliminary Study of the Clinical Hypoglycemic Effects of Allium cepa (Red Onion) in Type 1 and Type 2 Diabetic Patients
- Phytotherapy Research: The Influence of Raw and Processed Garlic and Onions on Plasma Classical and Non-Classical Atherosclerosis Indices: Investigations in Vitro and in Vivo
A certified nutritionist who majored in health, fitness and nutrition, Traci Vandermark has been writing articles in her specialty fields since 1998. Her articles have appeared both online and in print for publications such as Simple Abundance, "Catskill Country Magazine," "Birds and Blooms," "Cappers" and "Country Discoveries."