Onions can make you cry (or laugh, if you watch "Cry Onion", the 1975 Western movie with Franco Nero). Just like garlic, their relative, onions originated in central Asia and they were first grown in Iran and West Pakistan over 5000 years ago. No wonder, as onions are rich in sugars (there is a higher sugar amount in onion than in apples, that's why sauces with onion are sweet) and vitamins B6, B1 and B9.

Onions make you cry because when sliced, the cells release enzymes that break down sulfur compounds that generate sulfenic acids, unstable chemicals that turn into a volatile gas that reaches the eye through the air. To decrease the likelihood of tears, onions can be chilled for 30 minutes prior to cutting in refrigerator or cold water. If the root end of the vegetable remains attached, this too reduces the level of tear-provoking gases.

Onion (Allium cepa) has been known for long to be effective against the common cold, heart disease, diabetes and osteoporosis, improving also circulation, high blood pressure and impeding blood clotting. In many areas, onions are used for curing blisters and boils. In Malta wounds caused by sea urchin are treated by tying half a baked onion to the damaged area overnight.

A team at Japan's Hokkaido Tokai University has found a new quality for the old onion: it boosts your memory! Subjects experiencing memory loss reported improved recall abilities after ingesting lightly cooked pieces of onion.

The new discovery could be useful in the fight against brain conditions like Alzheimer's and Parkinson's. The Japanese researchers found an anti-oxidant chemical in onions which seems to attach to toxins in the brain, helping in eliminating them. The sulfur containing chemical is turned on when onions are slightly heated in a pan, but overcooking can damage the chemical's memory-boosting qualities.

The same active chemical is also encountered in other members of the Allium genus, like garlic (Allium sativum) and leek (A. porrum).