Can Onions Lower Your Risk of Heart Disease?

According to the Centers for Disease Control and Prevention (CDC), heart disease kills about 647 000 Americans every year. It is the leading cause of death for men, women, and people of most racial and ethnic groups in the United States of America.

There are many types of heart disease and they include congenital heart disease, arrhythmia, coronary artery disease, dilated cardiomyopathy, myocardial infarction, hypertrophic cardiomyopathy, mitral regurgitation, mitral valve prolapse, and pulmonary stenosis. Smokers, people with high blood pressure, people with high cholesterol, diabetics, physically inactive people, alcoholics, overweight, and obese people are at high risk of having heart disease.

Cardiovascular disease leads to a heart attack, chest pain, or stroke. It is caused by the build-up of fatty deposits, and cholesterol inside your arteries leading to the narrowing or blockage of your blood vessels. Thus blood flow to the heart muscle is slowed down or blocked. This puts you at risk of blood clots and heart failure.

Onions contain a large amount of quercetin. Quercetin is a flavonoid antioxidant. Flavonoids are a class of plant pigments that have a structure based on or similar to that of flavone. Flavone is a colorless crystalline aromatic ketone found in plants.

Quercetin is found in plants and foods including red wine, onions, green tea, apples, berries, Ginkgo biloba, St. John’s wort, American elder, and buckwheat tea. Since it is an antioxidant, it has anti-inflammatory properties. It helps decrease triglycerides and cholesterol levels thereby reducing blood pressure and heart disease risk. You can get quercetin supplements like these from Amazon.

Scientific evidence:

Verena Brull and colleagues, 2015, investigated the effects of regular intake of a quercetin-rich onion skin extract on 24-hour ambulatory blood pressure and endothelial function in overweight-to-obese patients with hypertension. It was a randomized double-blinded placebo-controlled cross-over trial. They found out that quercetin from onion skin extract reduced ambulatory blood pressure in patients with hypertension.

They concluded that the results suggested a cardioprotective effect of quercetin. However, there is need for studies on the mechanisms responsible for the blood pressure-lowering effect of quercetin.

Mehranghiz Ebrahimi-Mamaghani and colleagues, 2014, performed a randomized controlled clinical trial to evaluate the effects of raw red onion consumption on metabolic features in overweight and obese women with polycystic ovary syndrome.

The researchers found out that raw red onion consumption significantly lowered low-density lipoprotein cholesterol (bad cholesterol), and total cholesterol. They concluded that the intake of raw red onions appears to be an effective cholesterol-lowering food agent in women with polycystic ovary syndrome.

Nicholas K Gabler and colleagues, 2006, evaluated the potential health benefits of onions consumed at two levels of intake, using the pig model. They found out that eating onions regularly decreased plasma triglycerides levels. However, this study was done on pigs. Results obtained from animal experiments may be different from those obtained from humans. More studies need to be done on human subjects.

Marcela Alejandra Vazquez-Prieto and colleagues, 2011, evaluated the anti-inflammatory and antioxidant properties of garlic and onion in fructose-fed rats. They found out that garlic and onion consumption reduced oxidative stress, reduced vascular cell adhesion molecule-1 expression, and increased endothelial nitric oxide synthase activity. They concluded that the results showed the anti-inflammatory and antioxidant effects of garlic and onion.


In addition to reducing your risk of heart disease, onions have got many other health benefits including fighting against cancer, helping you control your blood glucose levels, boosting your digestive health, and fighting against bacteria.


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