Having high cholesterol raises the risk of heart attack and stroke, and taking immediate action to lower your cholesterol can help reduce the chances that either of these will happen to you. Including onions in your diet, along with making other lifestyle changes such as exercise, might help you accomplish that goal.

Alliinase and Other Beneficial Compounds

The compound in onions that might help lower cholesterol is called alliinase. This compound is released when an onion is cut or sliced, and it's also what makes you cry when you're chopping the vegetable. It's also the primary contributor to a decrease in heart problems when it comes to eating onions, according to a 2012 article published in the "Indian Journal of Clinical Biochemistry." In addition to alliinase, onions contain a variety of other compounds that might help lower cholesterol and improve health. For example, onions contain quercetin, plant sterols and saponins, all of which work together to make onions so beneficial to health.

Onions and LDL Cholesterol

Adding onions to a healthy and well-balanced diet might help lower cholesterol levels. An animal study performed in rats showed that the compounds in onions can reduce low-density lipoprotein, according to a 2012 study published in the "European Journal of Experimental Biology." LDL is the "bad" cholesterol that increases the risk of heart disease. Another animal study published in the "British Journal of Nutrition" in 2009 shows that onions can reduce serum and liver cholesterol levels.

Onions, HDL Cholesterol and Blood Pressure

At the same time that the compounds in onions can lower LDL cholesterol, they might also raise high-density lipoprotein, which is the beneficial kind of cholesterol that helps keep your heart healthy. The article in the "European Journal of Experimental Biology" notes that the compounds in onions can raise HDL cholesterol. The compounds in onions might also help lower blood pressure, a study published in the "Indian Journal of Clinical Biochemistry" notes. Combined with lower cholesterol, this effect can protect you from heart disease and heart attack.

Onions as Part of a Healthy Diet

Chop fresh onions and add them to spinach or pasta salads, or toss diced onions into vegetable or chicken noodle soup. Onions also add flavor to tacos, burritos, enchiladas, spaghetti and pizza. Saute sliced onions and add them to hamburgers or grilled cheese sandwiches as another way to include them to your diet. Slice onions into thick slices, brush them with olive oil and lay them directly on your outdoor grill. Flip the onions after about three minutes and grill them until they're soft and cooked through. Serve the onions with grilled meat and potatoes for a well-balanced and nutritious meal.