In our last column, we listed some well-known and not-so-well-known greens and gave a brief overview of their relative nutritional values. In this column, we talk more about greens in general and how you can make the best use of them in your diet.
With greens, it is the leaves and stems that are the source of nutrients. Many varieties of greens are rich in beta carotene and other carotenoids we know less about but which may turn out to be just as important as, or more important than, beta carotene. They also may be high in vitamin C and folic acid, which we now know is very important, especially for women of childbearing age. Greens also contain important substances that may help protect against cancer and other diseases.
And, as if that weren't enough, greens may be a good source of iron, calcium and other minerals, not to mention fiber. In countries with primarily vegetarian diets, like rural China, for instance, greens often provide the total intake of dietary calcium. Some greens high in iron and calcium (like spinach) are also high in substances called oxalates, which limit the availability of those nutrients to the body. But because of the complex makeup of the plant, greens still contribute enormously to a healthy diet.
Last, but not least, like most vegetable products, greens are fat free--as long as you don't sabotage them with high-fat add-ons.
As good as greens are, it is important for people taking blood-thinning medications such as Coumadin to be aware that many green, leafy vegetables are high in vitamin K, which helps promote blood clotting and may interfere with the action of the drug. Consult with your physician or other health-care professional about possible problems.
When shopping for greens, be sure they are refrigerated or kept on ice. Look for bunches without wilted or decayed leaves. Once you get them home, keep your greens in a plastic bag. If they were fresh, they should keep for at least a few days. Don't make the mistake that many people do of throwing away the dark green outer leaves, because they are usually the most nutritious.
If you have never tried cooking salad greens or using greens that you would normally cook as raw salad greens, you've missed a treat. By combining a large variety of greens in a salad, you will end up with a powerful nutrient package. Conversely, if you saute or braise lettuce or any other salad greens, you can serve it as a side dish or add it to soups and stews. There is no wrong way to do this.
Greens tend to be available year-round because most of the domestic crop comes from California. In your local farmers' markets, look for baby greens, which tend to be sweeter and more tender than more mature versions.
Food packagers have made it very easy to purchase a variety of greens without buying more than you need. You can now buy premixed greens in packages or in bulk, and although the per-pound price may give you some initial sticker shock, a bag that contains enough to make several salads weighs so little that it is actually a good bargain, especially when you consider how nutrient-dense it is. And the best part is that you can buy as much or as little as you want and have no waste.
People are often intimidated by making salad dressing and tend to purchase bottled varieties that can be very high in fat. But fear not. It is quite easy to produce your own dressing to control both the fat content and the flavor.
A classic vinaigrette dressing is the simplest to make. Normally you would combine 3 to 4 parts oil to 1 part vinegar. To cut down on the fat, you can try using a mild vinegar (like rice or balsamic vinegar and a stronger flavored oil, like sesame or walnut). That way you'll get all the flavor and be able to cut down on the amount of oil used. Vinaigrette can be seasoned with salt, pepper, garlic, herbs, spices, mustard, soy sauce, ginger, poppy seeds or any other flavorings that you particularly like.
If you want to try something creamier, try adding catsup or tomato paste and some pickle relish to plain, fat-free yogurt to make a dressing that's just as good as the high-fat Thousand Island version. You can also experiment with seasonings such as cumin, hot pepper sauce, cilantro or curry to add some zing to fat-free yogurt.
Don't make too much dressing at a time, so that you can vary the flavors from meal to meal. Three to four tablespoons of dressing should be more than enough for the equivalent of about two quarts of greens. Use the salad as an opportunity to add a wide variety of vegetables and other nutrient-dense foods to your meal.
Dr. Sheldon Margen is professor of public health at UC Berkeley; Dale A. Ogar is managing editor of the UC Berkeley Wellness Letter. They are the authors of several books, including "The Wellness Encyclopedia of Food and Nutrition." Send questions to Dale Ogar, School of Public Health, UC Berkeley, CA 94720-7360, or e-mail email@example.com.