Protect against: Cancer, birth defects, heart disease
Another member of the cruciferous vegetable family, Brussels sprouts contain the potent anticancer compound sinigrin which ’ persuades’ pre-cancerous cells to commit suicide - a natural process called apoptosis.
According to scientists at the Institute of Food Research in Norwich, the effect is so powerful that even the occasional meal of sprouts can destroy these cells.
Unfortunately for sprouthaters, the milder the sprout, the less potent the anticancer effect.
However, all sprouts are an excellent source of folate (the food form of folic aid) and can help reduce the risk of birth defects if eaten prior to and during pregnancy. Folate also reduces levels of a heart disease risk factor in the blood called homocysteine.
Protects against: Cataracts and macular degeneration
Two antioxidants in spinach - lutein and zeaxanthin - seem to protect against age- related eye diseases, including cataracts as well as macular degeneration.
It is thought the two phytochemicals - found in concentrated amounts in the retina - neutralise harmful free radicals generated in the eye through sun exposure.
In one American study, people who ate spinach 5-6 times a week had an 86pc lower risk of having advanced macular degeneration.
Curly kale is also rich in lutein and zeaxanthin.
Protects against: Osteoporosis, anaemia, fibroids
Eating 75g of watercress provides 16 pc of the recommended daily allowance (RDA) for calcium and 12 pc of the RDA for iron, helping to prevent osteoporosis and anaemia.
Women who eat lots of watercress and other green vegetables also have a lower chance of being diagnosed with fibroids (benign growths on the womb), according to researchers in Italy, though the reason why is not clear.
ONIONS AND GARLIC
Protect against: High cholesterol, heart attack, hay fever, cancer, inflammation
The sulphur compounds in garlic mean that a regular intake can help lower cholesterol levels and reduce blood clotting.
In a study at Newcastle’s Royal Victoria Infirmary, onions eaten with a breakfast fry-up reversed the normal tendency of the blood to clot after a fatty meal. Garlic also displays immune-boosting, anti-bacterial, decongestive and anti-cancer properties. A recent study of women in Iowa, U.S., found that those who ate garlic more than once a week were only half as likely as non-garlic eaters to develop colon cancer.
Yellow, and especially red (but not white), onions provide very high levels of quercetin, an antioxidant of the flavonoid family.
Quercetin is believed to help quell inflammation (for example of the joints) and allergic reactions (for example hay fever), as well as reduce the incidence of heart attacks.
Frying onions does not reduce their quercetin content.