In order for minerals in food to be utilized within the cells of the body, they must first be extracted from food, carried through the intestinal membranes, transported in the blood stream, and finally carried through the cell membrane to the interior cellular mechanisms. There are several barriers to this process. The most difficult being the intestinal wall. The cells that line the intestinal wall present a negative charge on the membrane surface. Minerals that have been dissolved in the digestive fluid which have lost their neutrality and have become positively charged will be attracted to the membrane and held tightly. In this instance, the minerals will not be allowed to pass through, and will remain held to the wall until another secretion cleanses them away. Picolinic acid is the body's prime natural chelator. There is an important reason for the body to construct this molecule: it is the most efficient chelator for minerals such as chromium, zinc, manganese, copper, iron, and perhaps molybdenum. A group of researchers led by Dr. Gary W. Evans at the USDA Human Nutrition Laboratory in Grand Forks, N.D., has been investigating Picolinic acid. Dr. Evans has found that Picolinic acid is produced from the amino acid tryptoph an in the liver and kidneys, and is transported to the pancreas. During digestion. Picolinic acid is secreted from the pancreas into the intestine. Dr. Evans has also determined that human milk contains fairly large amounts of Picolinic acid, whereas cow milk has little. Zinc is an essential trace mineral, which is second only to iron as the most plentiful trace element in the body. It aids in the absorption of B vitamins, it is a constituent of at least 25 enzyme systems, it is a component of insulin and of superoxide dismutase. Zinc is essential for growth and development of sexual organs, is important in nucleic acid synthesis and plays a role in carbohydrate and phosphorus metabolism.