Onion´s History:

Onions are one of the oldest cultivated vegetables in our history, originated from central Asia.
Ancient civilizations that used them became really dependent on them. Onions were easy to grow and easy to store. Onions proved to have a lot of benefits, so it was not strange to see that this vegetable quickly entered into religious ceremonies of several ancient civilizations. This was most apparent in Egypt, where onions were symbols of eternity, endless life and were part of burial ceremonies. Egyptians pained onions on the walls of their structures, pyramid, and tombs.  Onions were also an important part of the famous Egyptian mummification process.

Nutrition Facts:

Onions are vegetables that have been used for cooking and medicinal purposes for millennia. They contain a number of antioxidant compounds that are can help the body by neutralizing the free radicals present in our body. The impressive health benefits of onions include: prevent and relieve symptoms of cancer, heart disorders, and diabetes. They also help common colds, asthma, bacterial infections, respiratory problems, angina, and cough.

Health Benefits of Onion:

1- Reducing the Risk of Heart Ailments:
Onions act as anticoagulants (blood thinners) and this prevents the red blood cells from forming clumps. The use of onions is linked to preventing and reducing the risk of atherosclerotic disease. These clots can lead to heart disorders.

2- Anticancer Potential:
Onions have quercetin, which is a very powerful antioxidant, consistently linked to the prevention of the spread of cancer.
Onions also have Vitamin C, which also can reduce the presence and impact of free radicals in the body.
*Free radicals: chemical by-products of cellular metabolism and they can cause healthy cells to mutate into cancerous cells.

3- Relieve Stomach Aches:
Onions have anti-inflammatory and antibacterial properties that can relieve an upset stomach and related gastric syndromes.

https://www.organicfacts.net/health-benefits/herbs-and-spices/onion.html