Incredible health benefits of onions

As you read this, no doubt you have an onion in your pantry, ready and waiting to create the flavour base of a dish, to be caramelised into deliciousness or take the role of the hero in a simple soup or salad. Onions are incredibly versatile but they are also amazingly healthy. We will elaborate on the health benefits of onions...

Health benefits of onions

Image scource: Pixabay

The onion is very much an everyday pantry staple. A solid, dependable and versatile vegetable that lends itself to almost any cuisine worldwide. Looking back in history, it seems we are not the first to sing its praises.

The Ancient Egyptians depicted onions in paintings found in their pyramids, with traces of onion found in tombs. It’s believed that they were a symbol of eternal life, the layers representing the eternity of existence. Medicinally, they appreciated the circulatory, anti-inflammatory and “anti-snake” properties an important element at the time! Ancient Egyptians also used onion for antiseptic and deodorising, which is another useful trait both for everyday use and in preparing mummies for the afterlife.

The Greeks and Romans revered the healing properties of onions, using them liberally for food and medicine, and cementing their position of importance in the Mediterranean diet. In terms of medicinal use, Louis Pasteur, renowned biologist and microbiologist, was the first to discover the antibacterial qualities of onion (and garlic) juice in the 1800s, marking the beginning of research into this area.

Health benefits of onions: Healing punch

Onions (Allium cepa) are part of the Allium family along with their cousins garlic, leek, shallots, spring onions and chives. They are known for their high levels of organosulphur compounds, which are responsible for the pungent nature of these vegetables, along with a number of health benefits. These sulphur compounds transform to glutathione inside the body, which is one of our most important and powerful antioxidants. Sulphur compounds have been shown to have antibacterial, anti-inflammatory, antifungal, neuroprotective, anti-asthmatic and antithrombotic properties. They are protective of your liver and have also shown evidence of being anti-obesity, though more research is needed. These sulphur compounds are released from the onion when cut or crushed, so letting your onions sit for a few minutes after cutting and before cooking may help to preserve them, allowing you to get the most benefit.

It’s not only the sulfur compounds that contribute to the health benefits of onions, however. Other phytochemicals such as saponins, sapogenins and flavonoids have been shown to have further benefits. Flavonoids such as quercetin play an important role in cardiovascular health, protecting against LDL cholesterol oxidation and showing benefits for blood and circulation. They also have anti-spasmodic effects, which may help to explain the traditional use of onion in digestive complaints, helping to calm and reduce cramping or pain.

More recent research has looked at the cancer-preventive qualities of onions with positive results. For example, there seems to be a protective effect against lung cancer for those who have onions regularly in their diets, and there’s an association between onion consumption and reduced colon, ovarian and oral cancers. Studies have shown this effect via various biological pathways, however more research is needed, as these are only limited in number.

Looking at more traditional nutrients, onions are rich in vitamin C, which aids their anti-inflammatory and antioxidant effect further. They also contain biotin, copper, folate and vitamins B1 and B6. They are a great source of fibre and function as a prebiotic, assisting the growth of good bacteria in our guts and promoting a balanced microbiota.

Health benefits of onions: Cooking your onions

In terms of cooking methods, the flavonoid compounds of onion seem to be quite stable over sautéing and roasting at low temperatures. Boiling creates a loss of around 30 per cent, but this is transferred to the cooking water, so when making soups or stews you are still able to capitalise on maximum flavonoid action.

When preparing your onions, peel off as little skin as possible as much of those gorgeous flavonoids reside in the outermost layers. They love to be stored at room temperature in a well-ventilated area, away from heat and bright light. A wire basket or colander is perfect as it allows this airflow. Stored in this way, they should keep for about a month. Spring onions, however, should be kept in the fridge. Go for organic if possible, as the phenolic and antioxidant properties have been shown to be significantly greater in organic onions compared to conventionally grown.

The culprit that causes our tears when chopping these nutritional bombs is a gas called 1-propenyl-L-cysteine sulphoxide, also known as lachrymatory factor. Not everyone is irritated by this gas, but if you are, you may also be familiar with a number of suggestions to try to reduce this. Cutting onions by an open window may help, as might chilling the onions before cutting to attempt to slow down the lachrymatory factor production. I find after many years of sobbing over my onions that a nice sharp knife and a focused, quick job make for the best outcome. That, or borrowing my daughter’s swimming goggles.

I hope this has renewed your love and respect for the onion. It’s such a hard-working vegetable and it’s wonderful that it’s so accessible, flexible and delicious.