But however the kidney patient takes in calcium, it has to be done the right way, or the body won’t absorb it. You might think that just eating calcium-rich foods — like spinach, yogurt, nuts, or canned salmon — would be sufficient. But spinach contains oxalic acid, which binds to the calcium and prevents its being absorbed in the intestines. Milk contains lots of calcium, yet it’s eaten with spinach, again the absorption is hindered. Compounds in tea might produce a similar effect.
Most of the time, these small hindrances don’t matter much, as a person’s complete, healthy diet usually provides the calcium they need. But two factors come into play with kidney disease is involved. Adults, especially, already tend to absorb less calcium. If they’re not careful, their bodies get to a point where they use up stored calcium in bones and teeth more quickly than it’s replenished. Now add the fact that with kidney disease, the calcium/phosphorus balance is skewed so that, again, calcium drains from the body more quickly than it’s replaced. So how calcium is ingested, and with what, becomes important.
First of all, Vitamin D is necessary for absorption of calcium. So foods rich in this vitamin (fatty fish and beef liver, for example) will help produce the intestinal proteins that allow calcium to absorb. Even 15-20 minutes of direct sunlight each day, especially in summer, which allows the skin to create Vitamin D, can be enough. And most calcium supplements add the vitamin for this very purpose.
But it doesn’t hurt to investigate which foods, eaten together, might hinder the intake of calcium. (Too much magnesium may hinder the good work of Vitamin D, for example.) And learning which supplements may be better is also a good idea. For instance, it’s wise to avoid calcium derives from seashells, which may contain high amounts of lead.
Among all the side health issues stemming from kidney disease, calcium levels are very important. Careful monitoring and research into diet can help mitigate the problem.