求一篇关于营养学方面的英文文献

Trace elements
The human body is composed by 60 various elements. According to the element in the human body, can be divided into different levels of two kinds of elements and trace elements. The total weight of all the human element, such as the above 0.01 carbon, hydrogen, oxygen, nitrogen, calcium, phosphorus, magnesium, sodium, called macro amount. The total weight of all the human element, such as 0.01% below iron, zinc, copper, manganese, chromium, selenium, molybdenum, cobalt, fluorine, called the trace element. Trace elements in human body, such as zinc content is slim body total weight only three millionth 13. Iron is only 100 PPM.

Trace elements in human body, although the content, but with person's survival and health. They absorb excessive, insufficient, or lack of different degrees of human physiological cause abnormal or disease. The most prominent role of trace element is closely related with the vigor of life, just like a match that size or less o