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How Phytochemicals Work

What are Phytochemicals?


­Phytochemicals are natural compounds found in fruits and vegetables. They are substances that don't fall within any other categories -- they are not vitamins, proteins, carbohydrates, fats or minerals. Although they are not nutrients -- that is, necessary for sustaining life -- phytochemicals are beneficial to our health.

Each type of fruit or vegetable may contain hundreds of phytochemicals. An orange alone may contain 170 or more different phytochemicals.

Phytochemicals originated to help plants survive in an often hostile environment. When the Earth was young, there was very little free oxygen in the atmosphere. Plants, which take in carbon dioxide and release oxygen, eventually increased the oxygen composition. But by doing so, they polluted their own environment. To protect themselves from the highly reactive oxygen, plants developed antioxidant compounds, including phytochemicals. Today, thanks to these antioxidants, plants can survive -- and thrive -- in our oxygen-rich environment. Phytochemicals also protect plants against bacteria, fungi, viruses and cell damage.

The same phytochemicals that protect plants also help the humans who eat them. Researchers know that phytochemicals have antioxidant properties (meaning that they protect against substances called "free radicals" which can damage healthy cells -- see HealthCheck Systems: Understanding Free Radicals and Antioxidants to learn more). Scientists are also researching additional benefits:

  • Phytochemicals appear to protect against arterosclerosis -- the build up of fatty plaque on the artery walls that can increase the risk of heart attack and stroke.
  • Phytochemicals appear to protect against certain types of cancers.
But it remains uncertain how phytochemicals work and how much of them we need to eat to get the most benefit.

The Many Colors of Phytochemicals

Photo courtesy CDC, Morguefile

­Phytochemicals not only improve our health -- they also improve our enjoyment of food by painting the fruits and vegetables we eat in a rainbow of colors.

There are almost 2,000 different plant pigments in the foods we eat. Anthocyanins give strawberries, cherries, cranberries and raspberries their rich red color. Carotenoids give carrots their characteristic orange hue.