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.

  • Fentry

    Genetically Modified Carrots? Why is it that we’ll try any invention, any promise, craze, fad or guru, but we don’t do the one thing we know really works: eating (normal) foods properly and taking exercise?

    The implicit claim is that we need a Brave New World to be healthy–when we can be perfectly healthy in this one. Quite frankly, do people really believe more corporate foods/inputs will make Americans healthier?

  • Someone is probably confusing absorption and utilization. Vitamin D, which is fat soluble, is required for the utilization of calcium. Therefore, fat is required, albeit indirectly, for calcium to be utilized. As you say, it is probably absorbed equally well with or without fat. But I’m not sure how much good that does us if the body can’t properly use what it absorbs.

  • In the free transcripts of a series of
    seven useful and congenial audio interviews with leading nutritionist
    T. Colin Campbell, Ph.D., co-author of China Study, Dr. Campbell emphasizes that dairy is not helpful for prevention of osteoporosis:
    Dr. Campbell also details in the transcripts vitamin D metabolism and ways to get a sufficiency of calcium.

  • Hi Marion, To avoid bothering you, I googled CalciumAbsorption and learned more than necessary but have concluded that I ought to take the pills at the end of meaols even though practically everything interferes with their absorption, and here I am bothering you anyway. If you come to my house I can replace your broken sculpture with a more intact one. Sincerely, Joan von B.

  • Kelly

    Do you have any information on raw cow’s milk? We get ours from a local, organic dairy and love it. Just wondering how raw is different than pasteurized and the details, but have never been able to find a study. Thanks!

  • Others may disagree, but my understanding is that raw and pasteurized milk are essentially equivalent nutritionally. There are a few nutritional differences, but they are small. The main difference is that pasteurization kills most harmful bacteria in milk. I hope this answers your question.