Is spinach a good source of calcium?
Although food tables show that a cup of cooked spinach has almost
as much calcium as a cup of milk, the calcium isn't available in
a form that our bodies can absorb.
"The percentage of a nutrient that is actually absorbed from a
food is known as its 'bioavailability'," says Dr. Paul Nakata,
a plant physiologist at the USDA/ARS Children's Nutrition Research
Center at Baylor College of Medicine. Humans only absorb about five
percent, or 12 out of 244 milligrams, of the calcium present in
a cup of cooked spinach. On the other hand, about 100 of the 300
milligrams present in milk is absorbed.
Although bioavailability varies from food to food and nutrient
to nutrient, this isn't something consumers should worry about if
they're eating a healthy diet, says Nakata. The dietary recommendations
set for nutrients, such as calcium, have taken bioavailability into
consideration and also have a considerable margin of safety built
To make sure you're eating a healthy diet, follow the guidelines
set by the USDA/ARS Food Guide Pyramid. Those guidelines emphasize
a variety of foods that provide all the nutrients needed by healthy
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