"Got Milk?" We've all seen and heard the ads and "experts" telling us to increase our dairy intake in order to get enough calcium to keep our bones strong and decrease our risk for osteoporosis. If this is the case, then why does the U.S. have such a high rate of osteoporosis and one of the highest rates of dairy consumption? In fact the only countries with higher rates of osteoporosis have even higher rates of dairy consumption. So what's the deal? What the heck is going on here?
Here's the story, dairy foods are, in fact, high in calcium. However they are also high in animal protein. Several studies have proven that diets higher in animal protein and salt actually causes a leaching of calcium from the bones, and then it is lost in the urine. Unfortunately the rate of calcium loss from the animal protein and sodium is greater than the rate at which the calcium is absorbed. So you end up with a net calcium loss.
Absorption is another issue. The calcium found in plant foods is actually more readily absorbed by the body, without the detrimental effects of animal protein. The following table is taken from Disease Proof Your Child by Joel Fuhrman, M.D.:
100 calories of calcium % amount absorbed
Skim Milk 334 mg 32% 107 mg
Kale 449 mg 59% 265 mg
Bok Choy 787 mg 54% 435 mg
Broccoli 189 mg 53% 100 mg
So another way to state it would be to say, the less sodium and animal protein you consume, the less calcium you need.
I was shocked when I learned about this, and these are actually good studies! So think twice before you load up on the cheese and yogurt to "bone up" on calcium. You may want to consider reaching for some fruits and veggies instead.
Wednesday, May 12, 2010
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Good stuff, Melissa!
ReplyDeleteWe made up some hummus the other day and ate it all up.
Do you think this topic is related to the acid-ash hypothesis? The idea is that the net acidity or alkalinity of the diet as registered at the kidneys affects mineral absorption. While a couple of meta-analyses have not found broad support for it, I have read some compelling studies on the topic.
If it is true, since most whole grains and animal products are net acid forming, while vegetables and fruits are alkaline forming, eating a bunch of vegetables with grains and animal products could help with mineral absorption.
What are your thoughts on phytic and oxalic acids from grains and plants and their ability to reduce mineral bioavailability?
Yes, it does have to do with the theory that some acidic foods decrease this body's pH level (making it a more acidic environement).
ReplyDeleteRegarding specific acids and their effect on mineral bioavailability, I'm not sure. I'd have to research it. A great source for more detailed information on this topic would be Dr. T. Colin Campbell, nutritional biochemist, professor emeritus at Cornell University, and author of The China Study.