The Diet Detective's Guide to Phytochemicals

Fruits and vegetables, whole grains, nuts, beans, seeds - yes, there are reasons why you're constantly being told to eat them. They're healthy. And one of the key elements that makes these foods healthy is a group of compounds called phytochemicals.

What are phytochemicals?

Phytochemicals are compounds naturally occurring in plant foods (e.g., fruits, vegetables, grains, beans, nuts, seeds). The word "phyto" is taken from the Greek word meaning plant. So phytochemicals are plant chemicals. They are nature's way of protecting the plant from disease, and they affect humans in a variety of ways -- from imitating hormones (e.g., phytoestrogens) to altering blood ingredients in ways that may protect against some diseases.

According to Karen Collins, M.S., R.D., nutrition adviser to the American Institute for Cancer Research, there are two key concepts to understand about phytochemicals. "First, different plant foods contain different phytochemicals, each of which seems to act in slightly different ways on parts of cells. So to get the widest array of benefits, eating a variety of plant foods is important. And second, phytochemicals seem to work best in combination with one another. So even though you can get some particular phytochemical that you hear about as beneficial in supplement form, current research suggests that it will not function the same way when taken in isolation as it does when consumed as part of a food and a plant-based diet supplying a host of other phytochemicals."

What is the difference between an antioxidant and a phytochemical?

Antioxidants are a type of phytochemical with specific properties that seem to protect humans against diseases such as heart disease, cancer, diabetes and more. "However, exciting research continues to identify pathways through which phytochemicals impact health that seem to be outside their role as antioxidants. For example, some phytochemicals seem to stimulate enzymes that deactivate carcinogens before they can cause the initial cell damage that can begin the process of cancer development, while others can 'turn on' tumor-suppressor genes that trigger already-formed cancer cells to stop dividing and self-destruct," says Collins.

Are phytonutrients the same as phytochemicals?

According to Collins: Currently, the terms are being used interchangeably to describe those plant compounds that are thought to have health-protecting qualities.
Would you say that industrially processed foods are likely to contain fewer phytochemicals than unprocessed foods and therefore be less beneficial?
Unprocessed foods such as vegetables and fruits in their natural state, 100 percent whole grains, nuts and beans contain more protective phytochemicals. When a food is processed, most times it's stripped of many of these protective phytochemicals.

Can you explain the importance of bioavailability of phytochemicals?

"To be effective, a phytochemical generally needs to be absorbed by the cells of our body. So effects seen in test tube studies don't necessarily show what a phytochemical will do in our bodies," says Collins. For instance, a lab study might use grapes in much larger quantities than we would ever consume in order to show their ability to prevent disease.
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