Why Are Fruits and Vegetables Important for Health

Why Are Fruits and Vegetables Important for Healthwhy are fruits and vegetables important for health

In childhood, you were told countless times to "eat your vegetables." Eating fruits and vegetables is good for your health. But why?

Plants contain phytochemicals, or plant-derived chemicals. So far, more than 5,000 phytochemicals have been identified, of which vitamin C and vitamin E are well known. The functions and mechanisms of action of these two phytochemicals have been well researched and documented. Vitamin C and vitamin E are known as essential nutrients. However, we still have limited knowledge of the functions and mechanisms of the actions of thousands of other phytochemicals derived from vegetables and fruits.

Rooted deeply in the soil, plants are immobile and cannot move around. Unlike animals, they cannot just run away when threatened or in danger. To protect themselves against insects and other pathogens, the flowers, leaves, stems, and roots of plants contain insecticides and pesticides, collectively called phytochemicals. These phytochemicals can ward off bacteria and viruses and prevent damage by insects. Phytochemicals allow immobile plants to cope with adverse environmental conditions. From an evolutionary viewpoint, animals—particularly humans—evolved and adopted the natural defense mechanisms of phytochemicals in plants to cope with unfavorable environmental conditions. Phytochemicals became part of the cellular alarm system in the human body. As phytochemicals enter the cells, an alarm bell rings, signaling an immediate danger. Once inside a cell, phytochemicals activate transcription factors, which then move from the cytoplasm into the nucleus, where transcription factors trigger the expression of antioxidant genes in chromosomes and produce a host of antioxidant enzymes. Thus phytochemicals serve as cellular messengers to activate and strengthen antioxidant functions in the cell.

The phenomenon in which a small quantity of phytochemicals can induce profound amplification in cellular antioxidant functions is called "hormesis." Hormesis is a normal biological phenomenon characterized by low-dose stimulatory and high-dose inhibitory effects. For example, a small amount of vitamin A enhances vision, but a high amount can lead to anorexia, headaches, and lethargy. In toxicology, this phenomenon is called a "biphasic" reaction. Many known chemicals exhibit biphasic reactions in the body, including hydrogen peroxide, nitric oxide, and curcumin, and so does exercise. That's right—exercise also exhibits biphasic hormetic effects. Proper exercise improves cognition and strengthens muscle. Nevertheless, extreme exercise can be harmful to the body.

Phytochemicals are not easily absorbed in the intestines, and only a small quantity from food sources enters the bloodstream. The various colors of different parts of plants—red, yellow, green, blue, purple, and the others—are derived mainly from phytochemicals. It is best to include different colors of vegetables and fruits in your diet. Not only will this provide sufficient amounts of vitamin A, vitamin C, and vitamin E, but it will enhance the body's antioxidant capacity and immune functions.