Unfortunately as individuals, we can't do much to control the quality of the air we breathe. Getting that control will take more advanced social organization than we have right now. Water quality is a little easier for each of us to improve. If tap water is not pure, we can boil, filter or distill it or buy clean water from reputable companies to protect ourselves.

Green plants are the foundation of everything we eat. Even meat eaters prefer the meat from animals that eat green plants to the meat from animals that eat other animals. The exception to this rule is the fish we like to eat. They usually feed on each other.

The green plants that we eat are popularly divided into fruits, vegetables, beans and grains. Until recently we categorized the components of these foods as vitamins, minerals, fiber, fat, protein or carbohydrates. Some components were further classified as antioxidants.

Now because of the discovery of chemical compounds that do not fit neatly into any of the older categories, scientists have created a new category called phytochemical. Most people have heard of beta carotene, one of the best known of the thousands of phytochemicals. Now we know that there are at least 600 other carotenes. Beta carotene in plants is the precursor of vitamin A in animals. But we do not yet know the relationship between beta and the 600 other carotenes. Some other phytochemicals are indoles, over 1700 varieties of bioflavonoids, isothiocyanates and allium compounds. This list of phytochemicals is far from complete and will continue to grow as more research is done

The next logical question is, of what importance to our health is this information about phytochemicals? Some scientists believe that eating more vegetables containing these phytochemicals will help protect us against certain diseases. For example there is a phytochemical in soybeans and soybean products like tofu and tempeh that is believed to inhibit the growth of new blood vessels that cancer cells need to develop. Without this new blood supply, the young cancer cells will not get the nutrients they need to grow and will not get any larger than the head of a pin. It is also believed that lycopene, another carotene found in tomatoes and strawberries, is probably a protective agent against prostate cancer. We now believe that eating green and yellow vegetables can protect us against bladder, breast, cervical, lung, mouth, throat, ovarianand stomach cancers. According to the National Cancer Institute, approximately thirty-five percent of all cancer cases may be caused by a poor diet, one that is low in fruits and vegetables.

Does this new discovery of phytochemicals mean that we can expect to see bottles of phytochemical pills on the shelves of health food stores? Probably. But not because it is good nutrition. Two points must be kept in mind. The first is that we can only put into a pill what we know we have taken out of a natural product. Very little is known about how these chemicals work. Perhaps there is a relationship between some or all of the carotenes that allow the lycopene to work. Maybe it is the lycopene, fiber, vitamin C connection. Maybe it is the distribution of the phytochemicals in the plant's watery medium. These are all unknowns. Therefore we don't know what to put into the pill to make it work properly in our bodies.

The second point is, why bother processing these phytochemicals? Vegetables are readily available. They are delicious to eat and we don't have to know what they are composed of for them to work well in our bodies. Broccoli will not turn into pistachio ice cream and loose all its nutrients if we cannot list all of its disease-fighting properties.

My advice therefore is to eat at least five servings of green and yellow vegetables every day, Snack on citrus fruits, berries and grapes. Add some tofu or other soybean product to your protein allowance, and take a multivitamin/mineral supplement for insurance. This way you will cover all your bases. Remember the darker-colored parts of fruits and vegetables usually have higher concentrations of phytochemical and some other valuable nutrients. For example, in a single head of lettuce the dark green leaves are richer than the white or light-tinted leaves.