Top 7 Health Benefits of Onions [Plus Nutrition & Side Effects]

December 1, 2021

Every great cook knows the flavorful punch onions add to any dish. But you may not be as familiar with the health benefits of onions, which include everything from supporting both heart and skin health to fighting inflammation and even Alzheimer’s disease!

So, what makes onions so health-promoting? First, medium-sized onions are only 44 calories and don’t contain any fat. They also contain 11 grams of carbohydrates and 1 gram of protein. [1]

Finally, onions are healthy and delicious additions to many meals, whether they’re raw or cooked, and there are many varieties of onions to suit your needs for different dishes. Let’s take a closer look at the different types of onions and when to use each.

The Different Types of Onions

Onions are a part of the Allium family, which is made up of hundreds of flowering and vegetable plants. Other well-known plants in the Allium family include scallions, garlic, chives, leeks, and shallots.

If you know your way around the kitchen, you know that there are many different types of onions. They come in many colors, shapes, and sizes with the most popular varieties being red, yellow, green, and white onions.

Aside from their differences in color, each variety of onion has distinct benefits.

Yellow onions contain the most flavonoids, which have a variety of health benefits ranging from anti-inflammatory properties to cancer prevention. [2, 3] And red and yellow onions contain more antioxidants than white onions. [4]

Despite these differences, there are many onion benefits you can receive from each variety. Here’s a quick cheat sheet to help you know which onions work best for different dishes.


Benefits of onions - Dr. Pingel

The Top 7 Health Benefits of Onions

There are many ways that onions influence your health for the better by eating them in everyday meals. Here are a few of the top benefits of onions.

1. Support heart health

Onions benefit your heart health in numerous ways, from reducing your risk for heart disease to lowering your blood pressure. [5]

Studies show that onions can lower the levels of triglycerides in your blood. [6, 7] As you may know, triglycerides are a kind of fat that circulate in your bloodstream.

High levels of triglycerides put you at risk for developing heart disease and stroke. They can even harden your arteries to cause a serious condition called atherosclerosis.

Another study found that reducing cholesterol levels is another one of the top heart-healthy benefits of onions.

Researchers split study participants into two groups: One group consumed 40 to 60 g of raw red onion each day, while the control group only had 10 to 15 g. All participants were women with polycystic ovary syndrome who were either overweight or obese.

They measured the participants’ cholesterol levels over the course of eight weeks. While both groups experienced a decrease in cholesterol over the course of the study, the group that consumed the most raw red onion had a significantly larger decrease than the control group. [8]

2. Support skin and hair health

When it comes to the health benefits of onions, did you know that onion juice can help to regrow your hair? That’s right!

In a study from 2014, researchers followed the effect of crude onion juice on hair growth for people with alopecia areata. (This type of alopecia is an autoimmune disorder that causes patchy hair loss.)

The researchers directed the experimental group to apply crude onion juice to their scalps twice a day, while the control group did the same with water. Nearly 87 percent of those who applied crude onion juice to their scalps experienced hair regrowth. [9]

Interestingly, men experienced higher success with over 93 percent reporting regrowth, compared to 71 percent of women.

3. Improve bone density

If you’re searching for a natural solution to prevent osteoporosis, look no further! As you age, your risk for osteoporosis increases, but you may be able to improve your bone density with the help of onions.

Onions benefit your bones and can help prevent osteoporosis in multiple ways. Not only can it prevent bone loss, but it can also increase bone density.

One study found that onions prevent bone resorption in rats, while another found that bone mineral density in women improved with onion juice supplementation. [10, 11]

Additionally, it confirmed that women who eat onions at least once a day have a 5 percent higher bone density than women who eat them once a month or less.

So, what does this mean? If you’ve already been diagnosed with osteoporosis or your bone density is decreasing, onions may help you reverse some of your bone loss.

And if you don’t have lowered bone density, consuming onions daily can have a protective effect to help prevent bone loss in the future!

4. Contain anti-inflammatory properties

Another one of the incredible health benefits of onions is that they also contain anti-inflammatory properties.

Quercetin is an antioxidant found in onions, and it’s packed with benefits that can improve your health in many ways, including fighting inflammation. [12]

But onions don’t just treat inflammation on their own. Onion bulb extract can improve the effectiveness of steroids for anti-inflammatory treatments. [13] It’s even been shown to reduce colitis symptoms in mice by stopping the molecules that are responsible for inflammatory responses. [14]

5. Aid digestion

Did you know that one of the health benefits of onions is that they are a good source of prebiotics, which can help support your digestive system? [15]

Prebiotics are the insoluble fiber eaten by the bacteria in your gut. This encourages an ideal balance of flora that influences your gut health in positive ways and aids digestion.

Studies show that onions may also play a role in preventing colorectal cancer. The bacteria in your gut that are fed by the prebiotics in onions produce butyric acid.

So, consuming more prebiotics also increases the amount of butyric acid in your gut, which is shown to prevent colorectal cancer. It may even discourage the spread of cancer that is already present. [16]

However, if you’re experiencing symptoms of gastroesophageal reflux disease (GERD), you may want to rethink your gut health strategy. Onions can make GERD worse, so talk to your doctor about how you can improve your gut health in other ways.

6. Support immune health

Your immune system helps you fight off pathogens that can make you sick. And while people often talk about the immune system benefits of elderberries and vitamin C, did you know that one of the incredible health benefits of onions is that it supports your immune system?

Rats that consumed onion peel water extract supplements experienced a variety of benefits to their immune systems. They had higher levels of immune-related cells and some cytokines. [17]

Mice also experienced immune-boosting benefits when they consumed bunching onion mucus. [18]

A strong immune system is so important to protect yourself from bacteria, viruses, and other pathogens—and eating onions is an easy way to give yourself an extra boost to stay healthy.

7. May help prevent Alzheimer’s disease

Last, but not least, the benefits of onions also extend to your brain.

Alzheimer’s is a devastating neurodegenerative disease that causes you to lose your memory. Fortunately, there’s potential for onions to help improve memory for Alzheimer’s patients because they are high is quercetin.

One study found that mice with early-stage Alzheimer’s disease experienced significantly improved memory recall after they ingested onion powder that had high levels of quercetin. [19] Onion powder with lower levels of quercetin didn’t have as great an effect.

Considering the financial and emotional burden of Alzheimer’s disease, this finding is particularly significant. If people with Alzheimer’s disease can improve their memory, their quality of life may improve.


How to Use Onions

You can use onions in many different ways to experience the benefits they have to offer. Cooking with them, eating them raw, and drinking or applying the juice to your body can all benefit you in numerous ways.

One of my Top 5 Fast Healthy Dinner Ideas is to stock up on fruits and vegetables.

We all know that these are the key ingredients to a healthy lifestyle. Well, onions in particular are great to stock up on because they have a lengthy shelf life.

In fact, you can expect them to last up to three months if you leave them whole and keep them in a cool, dry place in your kitchen.

If you’re looking for a quick and delicious recipe you can use to tap into the health benefits of onions, check out my Ultimate Simple Pico de Gallo recipe. It’s an easy and refreshing snack that’s sure to put a smile on your face!

Key Takeaways

  • Onions are an easily accessible ingredient that can improve your health in many ways. No matter the variety, the health benefits of onions can be experienced throughout your body.
  • Many onion benefits are due to the high amount of quercetin they contain. This and other nutrients help onions fight inflammation, improve memory, support heart healt, and more!
  • Colorectal cancer and heart disease are two major illnesses that onions may help prevent, making onions a potentially life-saving food.
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