Phytonutrients are nutrients derived from plant material that have been shown to be necessary for sustaining human life. Phytochemicals are non-nutritive plant chemicals that contain protective, disease-preventing compounds. Their role in plants is to protect plants from disease, injuries, insects, drought, excessive heat, ultraviolet rays, and poisons or pollutants in the air or soil or water. They form part of the plants immune system.

Although phytochemicals are not yet classified as nutrients, substances necessary for sustaining life, they have been identified as containing properties for aiding in disease prevention. Phytochemicals are associated with the prevention and/or treatment of at least four of the leading causes of death in Western countries - cancer, diabetes, cardiovascular disease, and hypertension. They are involved in many processes including ones that help prevent cell damage, prevent cancer cell replication, and decrease cholesterol levels.

One of the most important groups of phytochemicals are the phytosterols or phytohormones as they are sometimes known. These are plant-based sterols that act as precursors to our human sterols. They act to modulate or regulate the human endocrine system. One of the most important human sterols is Dehydroepiandrosterone (DHEA). This hormone is produced in our adrenal glands and serves a variety of functions. It is often called the "mother" hormone as it has the ability to convert itself into other hormones such as estrogen, testosterone, progesterone, and cortisol. Thus, it is a precursor to all other hormones and active metabolites. Precursors are substances the body uses to produce other substances.

Scientific research has suggested that adequate DHEA levels in the body can slow the aging process, and prevent, improve, and even often reverse conditions such as cancer, heart disease, memory loss, obesity, and osteoporosis. DHEA blood levels peak between ages 20 to 25 years and then decline with age in both men and women.

DHEA is the precursor of our stress hormones such as cortisol and adrenaline. That is, our body makes cortisol and adrenaline from DHEA. When our body makes these hormones, DHEA levels decline. With our stressful lives it is no wonder that most people have deficient levels of DHEA and the medical conditions, and degenerative diseases listed above.

Dioscorea, found in the Mexican yam, contains a biochemical storehouse of valuable phytochemicals for use as hormone precursors. The molecular structure is almost identical to the body's natural hormone precursors.