People who have had kidney stones should read the section on kidney stones before considering supplementation. In that report, only bonemeal exceeded federal levels. People who decide to take bonemeal, dolomite, or oyster shell for long periods of time should contact the supplying supplement company to request independent laboratory analysis showing minimal lead levels. Vitamin D is needed for calcium to absorb. Therefore, many nutritionally oriented doctors recommend that those supplementing with calcium also supplement with 400 IU of vitamin D per day.
Calcium competes for absorption with a number of other minerals.
Therefore, individuals taking calcium for more than a few weeks should also take a multimineral supplement. Lysine supplementation increases the absorption of calcium and may reduce its excretion. As a result some researchers believe that lysine may eventually be shown to have a role in the prevention and treatment of osteoporosis . Refer to the drug interactions summary for calcium for a list of those medications. For the convenience of the reader, the information in the table listing the supplements for particular conditions is also categorized.