Meeting Vegetarian Calcium Needs for Good Health
For vegetarians, the amount of calcium that is actually absorbed and retained from dietary sources is probably a good deal higher than for most Americans, so recommended intakes could theoretically be lower. How much lower depends on a few factors.
The protein factor: The amount of protein in your diet probably has a greater bearing on the health of your bones than does the amount of calcium in your diet. Scientists think that the ideal ratio of calcium to protein is about 16:1.
The sodium factor: Like protein, sodium has a profound calcium-depleting effect on the body. Table salt and processed foods contain lots of sodium, as do canned foods and condiments such as ketchup, mustard, and pickles.
Read the labels on the packaged foods, and try to limit your sodium intake to not more than about 2,000 milligrams each day — good advice for vegetarians and nonvegetarians alike.
The phosphorous factor: Too much phosphorus (found in red meats and soft drinks) causes the body to lose calcium, as does the caffeine found in such things as cola drinks, other soft drinks, coffee, and tea.
The phytates and oxalates factor: Substances such as phytates and oxalates, found in plant foods, inhibit your body’s ability to absorb the calcium in the foods that contain them.
Whole grains are high in phytates, and spinach is high in oxalates, making most of the calcium in these foods unavailable to your body; however, cooking destroys oxalates makes the calcium easier to absorb. Some research shows that the calcium in kale, Chinese cabbage, and broccoli is absorbed better than the calcium found in cows’ milk.
The physical activity factor: The more weight-bearing exercise you include in your daily routine, the more calcium you’ll hang on to. People who walk regularly or engage in strength training by using a weight set at home or at the gym have denser bones than people who are couch potatoes.
The sunshine factor: Your body manufactures vitamin D when you are exposed to sunlight. And vitamin D helps your body absorb calcium.
The absorption factor: Your body adjusts the absorption of many nutrients, including calcium, according to its needs.
Protein from plant sources doesn’t have the same effect on the human body as protein from animal sources does because proteins from animal sources have more sulfur-containing amino acids. When you eat meat and other forms of animal protein, your blood becomes more acidic.
To neutralize the acid in the blood, your body draws calcium from your bones and sends it into the bloodstream. This calcium is eventually lost through your urine as your kidneys filter your blood. The sulfur also has an effect on the kidneys that causes more calcium to be lost in the urine.