Onions belong to the Allium family of plants, which also includes chives, garlic, and leeks. These vegetables have characteristic pungent flavors and certain medicinal properties.
Onions vary in size, shape, color and flavor. The most common types are red, yellow and white onions. The taste of these vegetables can range from sweet and juicy to crisp, spicy and tangy, often depending on the growing season and consumption.
Farmers have been growing allium vegetables for centuries. According to the Food and Agriculture Organization of the United Nations, China is the world’s largest producer of onions.
It is common knowledge that chopping onions causes watery eyes. However, onions can also offer potential health benefits. These can include reducing the risk of several types of cancer, improving mood, and maintaining healthy skin and hair.
In this article, we discuss the possible benefits of onions, their nutritional content, and how to include more of them in the diet.
Benefits of eating onions
Onions can have positive effects on several different aspects of health.
Researchers have extensively examined allium vegetables in relation to cancer, particularly stomach cancers and colorectal cancer.
The researchers found that the risk of colorectal cancer was 79% lower in those who regularly ate allium vegetables, such as onions.
Experts do not fully understand the exact mechanism by which certain compounds in onions inhibit cancer. Some hypothesize that onions inhibit tumor growth and cell mutation.
One cup of chopped onions also provides at least 13.11% of an adult’s recommended daily intake of vitamin C. As an antioxidant, this vitamin helps to counter the formation of radical compounds linked to cancer.
A 2015 review found a general relationship between increased consumption of allium vegetables and a reduced risk of cancer, particularly cancers of the stomach and gastrointestinal tract.
The authors note that there are compounds called organosulfides in onions, some of which suppressed aspects of tumor growth. However, they conclude that not all organosulfides have antioxidant properties.
More research is needed to confirm which compounds in onion have protective effects against cancer.
The review also identified gaps in the research to date. The authors suggested that onions and other allium vegetables do not prevent cancer in isolation but work in tandem with other lifestyle factors to reduce risk.
They also reported that while research has revealed some associations between consuming allium vegetables and reducing cancer risk, it is not yet clear how much a person should consume to get the maximum benefit.
Skin and hair
As a good source of vitamin C, onions can support the building and maintenance of collagen.
Collagen structures the skin and hair.
Moderation of blood pressure
A 2019 review found that quercetin, a compound in onion skin, had links to lowering blood pressure when researchers extracted it and gave it as a supplement.
However, the study did not examine the potential effects on blood pressure of eating onion as part of the diet rather than taking quercetin in supplement form.
Onions are a nutrient-dense food, which means they’re high in vitamins, minerals, and antioxidants while being low in calories.
One cup of chopped onion provides:
- 64 calories
- 14.9 grams (g) of carbohydrate
- 0.16 g fat
- 0 g of cholesterol
- 2.72 g of fiber
- 6.78 g of sugar
- 1.76 g of protein
Onions are a good source of the following nutrients, according to the Recommended Daily Allowance (RDI) and Adequate Intake (AI) values of the Dietary Guidelines for Americans.
Onions also contain small amounts of:
- the iron folate
- the antioxidants quercetin and sulfur
Risks associated with eating onions
Onions pose little risk to the people who eat them.
However, some people may have an allergy or intolerance to bunions. Anyone who experiences a reaction after eating them should be sure to see a doctor.
Why does chopping onions cause tears?
Onions have a reputation for making people cry during the cutting or chopping process. This response occurs due to the presence of a gas called syn -propanethial-S-oxide.
This chemical is a liquid compound that acts like a tear agent, which means it causes tears or stings the eyes.
To reduce tears while chopping, the National Onion Association recommends cooling an onion for 30 minutes, then cutting off its top. The person should then peel the outer layer of the onion and leave the root intact, as this part has the highest concentration of tear gas.
Despite the tears they can produce, onions can be a healthy addition to any diet. However, the overall diet of a person is the most important in disease prevention and good health.
When selecting onions, people should look for ones that are dry and firm with little to no fragrance before peeling them.
Including onion in a dish is a great way to boost flavor without adding calories, fat, or sodium.
Onions are a staple in many cuisines and complement most dishes. People can use raw chopped onion in a sandwich topping or as a salad garnish. This vegetable is also a tasty addition to salsas and dips.
Healthy recipes that include onions as a main ingredient include:
- Pickled onions
- Spanish omelette with potato and onion
- Dairy Free Onion Dip
- They also taste great when people sauté, roast, grill or caramelize them.
While onions are a great addition to a balanced, healthy diet, people should eat a variety of foods rather than focusing on individual options.
Are spring onions as nutritious as regular onions?
They are similar in nutritional content, but spring onions contain more plant-based antioxidants than bulbs because the leafy green part of the plant is more extensive.
Spring onions also contain B vitamins and many minerals, including copper, iron, manganese, and calcium. In addition, the leafy green part of the plant is a good source of folic acid.
However, as people tend to use spring onions as condiments and in smaller amounts than bulb onions, the nutrient intake is generally less.