A new study suggests that compounds in onions may protect the brain from additional damage linked to stroke.
This is hardly the first good news about onions, which I wrote about in depth in my book, “The 150 Healthiest Foods on Earth”. In a number of impressive published studies, the consumption of onions (and other members of the allium vegetable family) demonstrated protective effects against stomach cancer.
In one study, eating onions (as well as other members of its family like garlic, scallions, chives, and leeks) significantly lowered the risk for prostate cancer. Onions (and their close relatives have also been shown to have the same effect against esophageal cancer. In the new study, Korean researchers reduced blood flow in the brains of two groups of mice and then fed one of them onion extracts. The results showed that the onion group had significantly reduced brain edema (water in the brain, a common effect of stroke). No such reduction in brain edema was seen in the mice that didn’t get the onions. Other stroke-like damage was also reduced in the group that consumed the onion extracts.
Onions belong to the allium family, which also includes leeks, garlic, and shallots. They contain a whole pharmacy of compounds with health benefits, including thiosulfinates, sulfides, sulfoxides, and other smelly sulfur compounds. (Sulfur is great for you, but it stinks—think the New Jersey Turnpike!)
But those same smelly compounds offer a lot of nutrition bang for the relatively small price of a little eye-watering. In a study in the European Journal of Clinical Nutrition, onions are one of a very select group of foods that in combination was found to reduce mortality from coronary heart disease by an impressive 20 percent (the others included broccoli, tea, and apples).
Onions contain powerful antioxidants and are anti-inflammatory, antibiotic, and antiviral.
They are a great source of quercetin, one of my favorite anti-inflammatory compounds and one that is associated with beneficial effects on chronic disease like cancer and heart disease.
The class of chemicals that quercetin belongs to—flavonoids—have antiallergic properties as well, and quercetin in particular is frequently used by nutritionists as part of their arsenal for treating allergies with natural substances.
Quercetin can help relieve asthma and hay fever by blocking some of the inflammatory responses in the airways.
Our bodies absorb quercetin from onions very easily, though you’ll probably need quercetin supplements if your main interest is using it therapeutically as an anti-inflammatory.
Onions also contain a number of sulfides very similar to those in garlic, which may lower blood lipids and blood pressure.