by Marion Nestle
Jan 16 2008

Today’s question: calcium absorption

Amanda asks: “I also read that once you take the fat out of milk, it is difficult to absorb the calcium from it. Marion, can you state whether this is true?”

Oops. No. Where this idea came from, I can only guess. Fat is required for absorption of fat-soluble nutrients like vitamins A and E but minerals like calcium are water-soluble so would be expected to be absorbed better from watery solutions. As it turns out, calcium absorption has been measured under all kinds of fat conditions. The result: about the same proportion is absorbed from dairy products–about 30%–no matter how much fat they have. We tend to absorb smaller proportions of calcium from foods that contain a lot of oxalates (spinach and rhubarb for example). When dairy products are added to spinach, more of the spinach calcium is absorbed, so maybe that’s where the idea came from. Does this help?

And while we are on the subject, how’s this for a proposed solution to the non-problem of calcium absorption: genetically modified carrots! Bet you never thought of that one.