Physicians are trained in pharmacology (drug therapy) and only receive scant training, if any, in the science of nutrition. As a result, medical doctors are not your best source of knowledge regarding nutrition or nutritional supplements.
The hardest part for you as a consumer is that every mineral supplier claims to have the best product.
We've found that the best mineral "delivery system" is a concentrated, water-processed liquid from humic clay (ancient plant deposit) that is rich in fulvic acid. Tablets, capsules, and even powders fall short on at least two counts: