Eating Onions Has An Unexpected Effect On Your Cholesterol

Hypercholesterolemia affects a significant number of Americans. The U.S. Centers for Disease Control and Prevention (CDC) reports that approximately 2 in every 5 people across the country have high cholesterol levels that are equal to or exceed 200 mg/dL. That equates to roughly 40% of Americans.

Having high cholesterol can place us at an increased risk for potentially life-threatening health conditions such as stroke and cardiovascular disease. For this reason, it's important to keep our total blood cholesterol levels within normal range. Maintaining a healthy weight, exercising on a regular basis, and keeping alcohol consumption to a minimum are a few of the different ways in which we can protect ourselves from hypercholesterolemia. Diet is also a key factor. Eating high-fiber foods like beans, oatmeal, and avocados can help keep our "bad" LDL cholesterol down while boosting our "good" HDL cholesterol (per CDC). As it turns out, there's a powerhouse vegetable that can do the same. It may be a little pungent and it might make you cry; but it's the mighty, cholesterol-lowering onion.

Onions may lower bad cholesterol and boost good

Some of the different nutrients you'll find in 1 cup of cooked onions free of salt include 349 milligrams (mg) of potassium, 73.5 mg of phosphorus, 46.2 mg of calcium, and a little over 23 mg of magnesium (per U.S. Department of Agriculture). 

Onions also contain a flavonoid known as quercetin. Researchers from a 2017 study published in Lipids in Health and Disease set out to better understand the relationship between quercetin and its potential effects on reverse cholesterol transport (RCT), or the process in which the body removes cholesterol from the cells. Using mice who had been fed a high-fat diet, it was found that quercetin boosted cholesterol transfer, lowered cholesterol levels, and enhanced "good" HDL cholesterol functioning.

Even alternate forms of onion have been shown to offer these same cholesterol-lowering benefits. In an 8-week study published in 2015 in Plant Foods for Human Nutrition, researchers found that drinking quercetin-rich onion juice significantly reduced LDL cholesterol levels in patients with mildly high cholesterol.

Can onion supplements lower cholesterol levels?

We'd be hard-pressed to find a meal that onions wouldn't instantly make better. Whether you enjoy them cooked or raw, this vegetable can complement any salad, chili, burger, stew, and more. However, if you don't enjoy eating onions, onion supplements may also potentially lower one's cholesterol levels. Researchers from a 2021 meta-analysis published in Food Science & Nutrition examined ten different clinical trials and concluded that onion supplementation appears to lower levels of bad cholesterol, increase levels of good cholesterol, and regulate total cholesterol levels. However, no relationship was observed between onion supplementation and improvement in triglyceride levels and the researchers emphasized that more study is still needed.

Certain factors can place a person at an increased risk for hypercholesterolemia. This includes eating foods that are rich in trans fat or saturated fat, a sedentary lifestyle, smoking, genetics, age, and more (per CDC). The presence of alternate health conditions can also be a risk factor, such as type 2 diabetes or obesity. If you have concerns about your cholesterol, be sure to talk to your healthcare provider and keep up with routine physical exams.