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Calcium Absorption
Is there a problem with calcium absorption from some foods?
Calcium from many foods such as milk, cheese, yogourt, kale and tofu is well absorbed. Some substances in other foods bind calcium and make it unavailable for absorption. This is not a problem in a balanced and varied diet. Two common calcium-binding substances are oxalates (found in many green vegetables and chocolate) and phytates (found in unleavened grain products).
Ideas for Action:
- If green vegetables, legumes, nuts and seeds
are your main calcium sources, it is especially
important to depend on those that contain well-absorbed
calcium.
- If greens are significant calcium sources for
you, be sure to rely on low oxalate sources such
as broccoli, kale and bok choy or other mustard
greens.
- Don't worry about the oxalates in chocolate
milk. There aren't enough oxalates to interfere
with the much larger quantity of calcium.
- Try the Calcium
Calculator to discover a variety of calcium-rich
foods.
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Did You Know?
- Calcium absorption is dependent on many factors. The total amount of calcium in your diet and your calcium needs are probably most important in determining how much calcium you absorb from a food.
- Most researchers agree that the effect of calcium binding substances is not a problem if you eat a variety of well-absorbed calcium-rich foods. However, the calcium in high oxalate foods, such as those listed below, is unavailable for absorption.
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High oxalate foods
- beet greens
- chard
- rhubarb
- spinach
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Low oxalate, calcium-rich vegetables
- broccoli
- collards
- kale
- mustard greens
- turnip greens
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Phytate seems to be a problem only when whole grain
cereals are a major part of the diet (i.e. not just for
breakfast)
and calcium intake is low. Leavened bread does not present
the same problem since yeast fermentation breaks down
phytate.
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