What Phytochemicals Are and What They Do

By Jonathan Wright, Linda Larsen

Phytochemicals are natural compounds found in fruits and vegetables that help protect against the many causes of disease. Scientists think that plants developed these compounds to protect themselves against stress and environmental toxins. For instance, the brightly colored skins of many fruits and vegetables protect against the sun’s ultraviolet rays.

You won’t find phytochemicals in most refined foods. The cooking and processing necessary to produce refined foods destroys many phytochemicals. So why not avoid those products and enjoy whole foods instead?

Phytochemicals have many important roles in your body. They can act as any of the following:

  • Antioxidants: Antioxidants are natural chemicals that protect your cells against free radicals, which are rogue molecules that can cause damage that leads to diseases like cancer, diabetes, and heart disease. Some common antioxidants include carotenoids, flavonoids, polyphenols, anthocyanidins, and allyl sulfides.
  • Hormone imitators and helpers: Some phytochemicals can help regulate your body’s hormones. For example, isoflavones in soy can imitate the action of female estrogens to help reduce the symptoms of menopause. And a polyphenol in cinnamon can help improve insulin function.
  • Cholesterol reducers: Phytosterols reduce the cholesterol counts in your bloodstream and help accelerate your body’s natural cholesterol excretion methods.
  • Collagen producers: Anthocyanidins help boost collagen production in blood vessels and may help reduce the effects of arthritis.
  • Immune system stimulators: Flavonoids and phytoestrogens can help suppress tumor growth, and terpenes block proteins that overstimulate cell growth and reproduction. Other phytochemicals help increase the production and movement of white blood cells that protect your body against infection.
  • Enzyme stimulators: Indoles, which are found in cabbage, broccoli, cauliflower, Brussels sprouts, bok choy, and other vegetables, aid enzymes that protect cells against damage by balancing good and bad estrogens in the body. Protease inhibitors and terpenes also boost production of enzymes that inhibit the formation of cancer.
  • DNA replication interrupters: This category includes saponins, which are natural detergents found in many plants. These phytochemicals interfere with cell replication, possibly preventing the out-of-control cell growth that’s typical in cancer cells, but they don’t reduce or interfere with normal cell growth.
  • Cell binders: Some phytochemicals go directly to cell walls and bind to them, protecting the cells against pathogens like bacteria and viruses. The proanthycyanidins in cranberries, for instance, can help prevent urinary tract infections by blocking bacteria.
  • Bacterial, viral, and fungal fighters: Some phytochemicals destroy the invaders that enter your body through the food, water, and air you take in. For instance, allicin, a compound found in garlic, has antibacterial properties.

Because these powerful chemicals protect your cells, fight bacteria and other intruders (including free radicals), manage hormones, and aid enzymes, it’s no wonder that nutritionists have been urging people to eat lots of the fruits and vegetables that provide phytochemicals.

You can get phytochemicals in pill form, but you benefit more from eating them in their natural form as part of your diet. Here’s why:

  • Fruits and vegetables contain phytochemicals in many different forms and combinations that are impossible to replicate in a single pill. And the size of a pill that contained all the antioxidants available in fresh produce would be impossible to swallow!
  • Scientists haven’t discovered all the phytochemicals that nature provides, so you can’t find them in any available supplement.
  • The way these natural chemicals react in the body is extremely complicated and difficult to test and replicate in a lab, so relying entirely on supplements rather than fruits and vegetables is problematic.