While some nutritional scientists were studying populations and disease rates, others were using new analytical tools to probe deeper into the biochemistry of food and how it interacts with the human body. By the mid 1950s clues about degenerative diseases and their prevention were pointing researchers towards oxygen free radicals and antioxidants.
A free radical is an unstable molecule that is missing at least one electron. It will react with almost any other molecule it might bump into creating biochemical chaos in the process. As free radicals randomly react with proteins, carbohydrates, fats and DNA, they can disrupt normal cellular functioning throughout our bodies.
The seriousness of this random chemical activity within our carefully organized biological system can be seen from the list of ailments thought to be related to oxygen free radical activity. These include: cancers, heart disease, stroke, arthritis, Parkinson's disease, Alzheimer's disease, cataracts, and emphysema. Free radical damage is even thought to cause much of the tissue degeneration that we think of as normal aging.
Where do these troublesome molecules come from? Normal cellular activities create some free radicals so there is no avoiding some of them. We are also exposed to varying amounts of additional external sources of free radicals, coming from cigarette smoke, pollutants, some drugs and ultraviolet light or radiation.
How can we defend our bodies from oxygen free radical damage? Some of the external free radicals can be reduced through prudent actions, such as quitting smoking and using sunscreen. However, it has become increasingly difficult to avoid environmental pollutants. We have introduced more than 80,000 man-made chemicals into the environment in the past sixty years and the long-term impact of most of them is unknown. Until our industries and the environmental groups that monitor them can significantly reduce the load of pollutants, nutritional science may be our best ally.
Antioxidants are molecules that neutralize the oxygen free radicals and can prevent the damage to our cells. Like the free radicals they neutralize, some antioxidants are internally produced by our bodies and some must come from external sources. There is not much we can do about internally produced antioxidants, but fruits and vegetables are rich sources of external ones and eating more of these foods is a realistic way to increase antioxidant activity in our bodies.
Having observed that people who ate more fruits and vegetables had fewer cancers, scientists next tried to isolate the active antioxidant ingredients that were responsible for reducing the risk of cancers. They focused first on beta-carotene, the pigment that makes carrots, pumpkins, and sweet potatoes orange. They were quite shocked when three large well-structured studies showed that beta- carotene alone did not reduce cancer risk. Very gradually the scientific community stopped looking for the antioxidant Silver Bullet. They came to believe the anti-cancer benefit derived from a huge variety of antioxidant compounds, including 670 different carotenoids, found in a wide range of whole fruits and vegetables all working together.
It is ironic that the most sophisticated biochemical research has shown that our best defense against the more than 50 diseases linked to oxygen free radical damage is exactly what everyones mom suggested, "Eat your fruits and vegetables." This is why the simple message to eat five or more servings of fruits or vegetables every day can be such a powerful force for good health throughout the world.