"The most essential mineral elements of the body composition, in the order of their apparent importance, are iodine, copper, calcium, phosphorus, manganese, sodium, potassiuim, magnesium, chlorine, and sulfur. All but the first of these iodine, which is a native of the sea, have their source in soil. We would naturally suppose that when we eat products of the soil we should secure an ample supply of them. That is no doubt what Nature intended. But Nature did not foresee that man would remove the trees and other growth allowing the rains to erode the soil, leaching out the essential minerals and, by means of our creeks and rivers, carrying them down to the sea. The result has been mineral-starved soils, in turn producing mineral-starved foods. The obvious result is that humans, who depend upon these mineral-starved foods for our supply of minerals, are literally starving in the midst of plenty.
It is easy to know when one is hungry for sweets, starches, or fats. The body sends out distress signals almost immediately and, if we are in normal health, our appetite tells us what is needed.
Once we learn to know them, the signs of mineral hunger are quite as definite and the results, if our body's SOS is long ignored, are far more serious.
There have developed within the last few generations especially here in the United States, where food is most -abundant and the average person eats most generously, a whole series of "deficiency diseases." It is recognized that each of these diseases is due to a lack of vital elements in the diet, and the essentials most often lacking are the essential minerals. The thyroid requires iodine. The parathyroid requires cobalt and nickel. The adrenal glands require magnesium. The pancreas requires cobalt and nickel. The anterior pituitary gland needs manganese. The posterior pituitary needs chlorine. The gonads require iron.
An entirely new respect is being acquired for iron, copper, manganese, zinc, and aluminum, for it has been discovered that these minerals have a most profound influence as catalysts, or electrifiers, or self-starters, in our body processes in general and upon the formation of good and plentiful blood in particular."
more here:
http://www.jcrows.com/kelp.html