Most people believe that they are getting all the minerals they need simply by eating a balance of food from the four food groups. The sad truth is that most food is produced from soil that is grossly deficient in minerals, because farmers typically add to the soil just three minerals (nitrogen, potash or potassium, and phosphorus) to maximize their crop yield. Adding more minerals increases costs without producing more crops, so farmers have no incentive to do so.
The U.S. Government was concerned enough about the mineral deficiency back in 1936, when the Senate produced document number 264, which stated that food produced on mineral deficient land was starving us of perfect health. Nothing has happened since then to correct the problem.
Luckily, we can obtain the missing essential minerals from nutritional supplements. These vary in effectiveness depending on their form and source. Tablets usually contain just a few minerals in the metallic form and are 5% to 15% absorbable by the body. Some are in the form of chelated minerals, bound with an amino acid, and are a little better at 30% to 60% absorbable. Best of all are minerals in plant-derived colloidal form -- these are over 90% absorbable.
These highly absorbable trace minerals are combined with major minerals, vitamins and other beneficial ingredients, to produce very effective multi-supplements.