Mankind evolved on Earth when it was already filled with plant life, and plants influenced human evolution. Plants interact with the atmosphere differently than humans. While humans consume oxygen and produce carbon dioxide, plants take in carbon dioxide from the air and produce oxygen. This oxygen produced by plants is a chemically reactive compound that would damage and kill the plant, so plants evolved the ability to make antioxidants such as Vitamin C, Vitamin E and colorful chemicals to protect their cells from the damaging effects of oxygen. This system sometimes breaks down and the damage from oxygen can be seen when a houseplant gets too little light or water and its leaves turn brown.
The oxygen we breathe can also damage human tissues, as illustrated by the damaging effects of 100 percent oxygen in intensive care units, where the lung tissue can be destroyed without proper protection. Like plants, humans evolved defense systems that are based on circulating substances and proteins. These systems are reinforced with the intake of antioxidants in the diet from colorful fruits and vegetables. There is overwhelming data showing that populations that consume a diet rich in colorful fruits and vegetables have lower risks of many common chronic diseases.
It takes very little to avoid vitamin and mineral deficiencies, but the optimal levels of intake of antioxidants are likely greater than the amounts needed to avoid deficiency.
For example, humans, unlike many species of animals, have lost the gene for making Vitamin C, because it was part of ancient mankind’s diet, which was rich in Vitamin C from fruits and vegetables. Eating a single orange provides twice the recommended amount of Vitamin C needed to prevent Vitamin C deficiency. In the 1750s, sailors in the British navy developed the disease called scurvy, characterized by bleeding gums, corkscrew hairs and ultimately death, from a lack of Vitamin C. It was customary for sailors to eat no plants at sea. However, once it was discovered that eating limes or other citrus prevented scurvy, citrus became part of the sailors’ diets (which is why British sailors were called limeys).
Today, inadequate intake of antioxidants is not as noticeable as the deficiency disease of scurvy, but the inadequate intake of plants, including colorful fruits and vegetables, is thought to be associated with many chronic diseases of aging.
Recent studies in mice have indicated an interrelation between energy balance, diet, and the composition of the gut bacteria.
The Fitness Textbook will teach you the basic principles of human performance nutrition, including muscle metabolism and fuel utilization before, during and after exercise.