Let’s consider the lowly onion! It may not appear to be much, but wait until you see all the nutritional and medicinal effects produced by an onion (Allium cepa). No wonder it’s so widely used around the world. Onions have been shown to be anti-hypertensive in a number of animal studies. Onions contain prebiotics, poorly absorbed carbohydrates which serve as food for the healthy bacteria in our gastrointestinal tracts.
A little bit of chemistry might help here. Polyphenols are a major class of nutritional substances, as are carbohydrates and amino acids. Primarily, they give fruits and vegetables color and flavor. Polyphenols which contain no nitrogen are called flavonoids. Quercetin is the major flavonoid found in onions, responsible for many of the health benefits. However, quercetin may be destroyed by cooking.
Polyphenols are found in high concentrations in the gastrointestinal tract, where they are anti-inflammatory. The concentrations are high because they are poorly absorbed into the blood. Allium plants, including onion, contain N-acetylcysteine (NAC), which in combination with bromelain has been shown in test tube studies to inhibit growth and spread of gastrointestinal cancer cells.
Polyphenols also protect the dopamine-producing cells of the brain from damage. According to rat studies, researchers believe that more studies should be done of flavonoids in Parkinson’s disease since they do cross the blood-brain barrier even when consumed orally.
Flavonoids are high, especially in the red, smaller, more pungent onions. The outer layers are highest. Frying onions robs them of 33% of their flavonoids; baking is best. Sweet onions are lower in flavonoids as are dried onions.
The Mediterranean diet in general is considered to be quite healthy for humans. Greeks eat large amounts of wild onions, which contain more of the health-giving chemicals than the cultivated onions. Wild greens are considered to have higher levels of flavonoids in general.
Quercetin from onion and polyphenols are natural antioxidants. By relieving oxidative stress, quercetin helps avoid the risk of cardiovascular disease. It also may resist multidrug resistance (MDR), a problem in which all chemotherapy fails. Quercetin has also been shown to increase the absorption of chemotherapeutic agents. A definite recommended dose of quercetin has not been yet determined.
Quercetin consumption reduces lung cancer risk. One study showed that those with the highest intakes of quercetin had the lowest risk of developing lung cancer. It blocks angiogenesis, beneficial in cancer treatment since cancer can’t grow when the growth of new blood vessels is blocked. Selenium, a mineral important for healing cancer, autoimmune disease, and a number of other types of diseases, is found in abundance in onions.
In one study, red onions were included in a nutritious drink provided for young male terminal cancer patients. The drink was said by the patients to improve their sexual activity, and it turned out that something in onions is a phosphodiesterase-5 inhibitor (same as Viagra.
Now, do you have more respect for the lowly onion?
Rainbow Grocery sells the following products: Flavonoids, NAC, quercetin, and onions.
Summary #984. nutrientmedicine