Sunday, December 21, 2008

Nutritious, Delicious Watercress

Watercress conjures up an image of English nobles at high tea, nibbling tiny sandwiches of watercress and while balancing cups of tea. Otherwise, what is the watercress used for? Although watercress sandwiches are commonly served at English high teas, this peppery salad green is also one of the most popular vegetables in Chinese cooking and one of the most potent vegetables for fighting cancer.

The watercress of a crucifer, in the same family as broccoli, cabbage, kale, and mustard greens. These veggies are excellent sources of a family of cancer-fighting chemicals known as isothiocyanates. Most crucifers contain up to a hundred different isothiocyanates. Watercress contains a high concentration of just one, phenethyl isothiocyanate, or PEITC.

At least in preliminary studies in the laboratory, PEITC neutralizes one of the most deadly carcinogens in tobacco, a nitrosamine called NNK. When the bodies “watchdog genes” are inadequate to stop the multiplication of prostate cancer cells, other studies suggest, PEITC serves as a signal to the cancer to go through a phase called apoptosis, or “cellular suicide.” PEITC reduces the risk of breast cancer in laboratory animals. Even more importantly, PEITC deactivates the liver enzyme P450 2E1 that converts many common chemicals into carcinogens in the first place.

Eating watercress is known to lower the risk of cancer, the evidence coming from New Zealand. The nation of New Zealand as a whole has an extraordinarily high frequency of colon cancer, but the Maori population does not suffer the disease nearly as often.

A national nutrition survey even found that the relatively cancer-free Maori eat more meat, more red meat, more saturated fat, drink more alcohol, have higher rates of obesity, and eat fewer fruits and vegetables. The conventional wisdom would predict that Maoris, not non-Maoris would have the higher rates of colon cancer.

But Maoris eat large quantities of watercress and nettles. A later study found that watercress provides chemicals that stop the conversion of compounds in grilled and fried meats into their carcinogenic forms.

Eating watercress is even good for your heart. No plant foods contain more beneficial “n-3” fatty acids than mint, chia, and watercress. These fatty acids, chemically similar to those in fish oil, help the heart beat regularly and lower risk of sudden death.

And the peppery flavored watercress even affects your brain, changing the chemistry of the pleasure chemical dopamine so that you are more satisfied after eating a meal including watercress. The brain boosting effect is greatest in raw watercress, but symbiotic bacteria in your digestive tract—the good bacteria you get from yogurt—can increase both the pleasure chemicals and the anti-cancer chemicals obtained from cooked watercress.

Use watercress as you would any salad green, by itself or mixed with milder lettuces. You can add watercress to stir fries, of jazz up pasta or potatoes. Mak ea green sauce to accompany baked chicken or salmon by heating puréed watercress with a little olive oil, butter, or cream with a sprinkle of nutmeg. And, of course, you can use chopped watercress at your next afternoon tea party. Trim crusts from slices of a good white bread, lightly spread with butter, fill with watercress, raise pinky, and enjoy!

Recent reader questions:

Q. Is watercress goitrogenic (does it cause goiter, enlargement of the thyroid gland)?

A. Non-toxic goiter results from getting too little iodine in the diet, and is extremely rare in this age of iodized salt. (Toxic goiter can result from other causes and is a more serious condition with similar physical symptoms; it usually results from neck radiation for cancer.) Although it was once believed that watercress, mustard, cabbage, broccoli, collards, and other similar vegetables could deplete iodine and cause goiter, this is no longer thought to be the case.

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