Onions belong to the allium family of vegetables and herbs, which includes chives and garlic. Ancient civilizations cultivated onions for their flavor and their health benefits. They were grown 5,000 years ago in parts of Iran and West Pakistan, and they were also cultivated in parts of China, India, and Egypt around 3500 B.C. Today, onions are consumed around the world. The biggest producers of onions are China and India, followed by the United States.
Onions vary in size, shape, color, and flavor.
- Yellow onions: most common type with a pungent flavor and aroma
- Sweet onions: contain extra sugar and have a light color
- White onions: white skin and sweeter taste compared to yellow onions
- Red onions: magenta color with a sweet and mild flavor
- Shallots: small brown-skinned onions with purple flesh
- Green onions: immature onions that have not formed a bulb
- Leeks: look like overgrown scallions and have a mellow flavor
Onions contain plenty of antioxidants and sulfur compounds. A medium-sized onion is made mostly of water, but it also has fiber, carbohydrates, and protein. Onions contain vitamins and minerals including vitamin B6, vitamin B9, vitamin C, potassium, and folate. Their unique flavor and sulfur compounds make onions one of the best choices for flavor and prevention.
Health Benefits of Onions
In addition to many nutrients that have beneficial effects, onions also contain sulfur compounds, which have the ability to boost health and prevent cancer.
Studies show that the sulfur compounds contained in onions can help prevent the development of tumors by protecting cells from mutation. Regarding colorectal cancer, for example, results showed that consuming more than seven servings of onions per week can reduce the risk of developing this type of cancer. Using data from an integrated network of Italian and Swiss studies, researchers analyzed the relationship between frequency of onion intake and cancer. Results showed an inverse association between the frequency of consumption of allium vegetables such as onions and garlic, and the risk of common cancers, such as stomach and colorectal cancers.
Onions also contain vitamin C that helps fight the formation of free radicals, which can cause cancer. Additional studies related to prostate cancer found that men with the highest consumption of allium vegetables had the lowest risk of prostate cancer. Another team of researchers demonstrated that onions have potential protective effects on esophageal and stomach cancer.
Onions can enhance bone mineral density, which lowers the risk for fractures. A study on the relationship between onion intake and bone density in perimenopausal and postmenopausal non-Hispanic white women 50 years and older found that bone density increased in women who ate more onions. Women who consumed onions once a day had a higher bone density than those who consumed onions once a month. The team of scientists concluded that consuming onions frequently may decrease risk of hip fractures by more than 20%.
Onions have anti-inflammatory properties, and for this reason, they are an excellent food choice for people who suffer from inflammatory diseases like arthritis. Onions contain quercetin, a chemical compound that can may be a natural drug for treatment of arthritis. Quercetin helps inhibit inflammation-causing leukotrienes, prostaglandins, and histamines that worsen pain.
A study conducted in Korea found that onion extract can help fight diabetes by lowering plasma glucose concentrations and body weight. Onions are an excellent natural way to control blood sugar levels, and they provide the body with chromium, an essential mineral that regulates blood glucose and may reduce the risk of developing diabetes. Studies examining the role of chromium in insulin resistance showed that people with type 2 diabetes have lower blood levels of chromium than those without the disease.
The antioxidants contained in onions can have an impact on sperm health parameters. A study investigating the androgenic activity of onions on spermatogenesis in rats found that the total testosterone and sperm concentration increased in the rats that received high doses of onions over the course of 20 days.
Onions also contain folate, which helps to reduce depression. Researchers concluded that individuals with depression have lower serum levels of folate than individuals without depression. Folate also prevents an excess of homocysteine from forming in the body. Homocysteine is associated with cerebral diseases, depression of mood, and also interferes with the production of serotonin, dopamine, and norepinephrine, neurotransmitters that regulate mood, sleep, and appetite.
Cooking with Onions
Onions are versatile vegetables. They can be roasted, grilled, caramelized, chopped, and added to salads or used as garnish for tacos. Their flavor ranges from pungent to sweet.
Yellow onions are the most common type, and they can be prepared in a variety of ways. If a recipe does not specify which type of onions to use, you can assume that a yellow onion will do the job.
Sweet onions are great for caramelizing, while white onions are perfect for fresh salsa and guacamole. Red onions and green onions can be added to salads and sandwiches.
Onions can offer health benefits whether raw or cooked, but raw onions have higher levels of sulfur compounds, which can help the body in numerous ways.
Here are a couple of recipes with raw onion.
Israeli Couscous Greek Salad
This salad is rich in flavor and nutritional value, but light and easy to digest. It is a fast recipe—perfect for weeknights.
Ready In: 30 Minutes
- 1 cup Israeli couscous
- 1 Roma tomato
- 1 cucumber
- 1/4 cup minced onion
- 1/2 cup Kalamata olives
- 4 tablespoons extra virgin olive oil for the dressing
- 3 tablespoons extra virgin olive oil to cook the couscous
- 2 tablespoons apple cider vinegar
- 2 tablespoons honey
- Black pepper
- Mince the onion.
- Dice the tomato and cucumber.
- Chop the olives.
- Put all the veggies in a big bowl and set aside.
- Cook the couscous in extra virgin olive oil for 5 minutes until it gets golden.
- Add 2 cups of water to the couscous and cook for around 12 minutes.
- Dressing: whisk extra virgin olive oil, apple cider vinegar, honey, salt, and pepper.
- When the couscous absorbs the water, turn off the heat, pour the couscous in the bowl with veggies, and add the dressing.
- Couscous: made with whole-wheat or white flour. Like pasta, it fuels brain and muscles.
- Tomato: contains antioxidants, which reduce the risk of heart disease and cancer. It is also an excellent source of vitamin C.
- Cucumber: helps you stay hydrated and improves digestion.
- Olives: offer up antioxidants that can help prevent cancer and heart disease.
- Onion: contains sulfur compounds and minerals that can help protect against cancer and reduce the risk of diabetes.
- Extra virgin olive oil: lowers high blood pressure and supports brain health.
- Apple cider vinegar: helps lower cholesterol and blood pressure.
- Honey: contains antioxidants and is an excellent alternative to sugar.
- Black pepper: helps digestion and reduces high blood pressure.
Guacamole is an excellent snack and a great way to entertain guests. The mayonnaise makes it creamy and even more delicious.
Ready In: 15 Minutes
- 1 avocado
- 1/2 cup diced tomato
- 1/2 cup minced onion
- 1/4 cup lime juice
- 1 teaspoon mayonnaise
- 2 cloves garlic
- A few stems of cilantro
- A dash of cayenne pepper
- Black pepper
- Cut the avocado and mash it with a fork in a small bowl.
- Add mayonnaise and mix.
- Dice tomato and onion, and mince the garlic.
- Add the veggies to the bowl and mix.
- Add salt, pepper, and cayenne pepper.
- Add the stems of cilantro.
- Serve with tortilla chips.
- Avocado: high in heart-healthy monounsaturated fatty acids and helps lower bad cholesterol and promote weight loss.
- Tomato: packed with antioxidants, which help reduce the risk of heart disease and cancer. It is also an excellent source of vitamin C.
- Onion: full of sulfur compounds and minerals, which can help prevent cancer and reduce the risk of diabetes.
- Garlic: loaded with compounds that help fight diseases, from common colds and infections to diabetes and cancer.
- Lime: improves heart health and boosts immunity.
- Cilantro: protects against oxidative stress and helps lower blood sugar levels.
- Black pepper: helps digestion and reduces high blood pressure.
- Cayenne pepper: lowers blood pressure and supports digestion.
- Mayonnaise: contains amino acid-rich eggs, but also a lot of fat. Experts recommend consuming mayonnaise in moderation because it is high in calories. Make sure you buy a good quality mayonnaise, possibly organic, without added flavors.