The MOST critical time for formation of the calcium matrix of bone which is specific for women is from about 2 years before the menses starts to about 5 years after, approximately age 9-16. Women also lose calcium from the bone easily, due to metabolic and hormonal shifts, both during pregnancy and during and after menopause. Protect women you care about by providing enough calcium in food and supplements at these times.
You must have vitamin D from supplements or sunshine to absorb dietary calcium. Daily, one half hour of sun on normally oily skin provides sufficient vitamin D precursor.
Calcium is more poorly absorbed by folks eating a high protein diet, or high phosphorus foods (such as soda pop and milk). Calcium also is not well absorbed from sesame seeds unless they are ground or pulverized. A recent study(1) compared the absorption of calcium from kale with the absorption from milk revealing absorption of calcium from kale was 40.9%, compared with 32.1% from milk.
One cup of cow's milk contains approximately 300 mg of calcium. In the USA, the recommended daily allowance (RDA) for adults ranges from 800 milligrams to 1200 mg for pregnant or lactating women. Research with pregnant and lactating women in rural African communities has shown that they maintain good bones on a much lower intake, less than 400 milligrams per day. These women get plenty of sunshine, use highly bio-available sources and their diets do not contain excessive phosphorus or protein.
USDA nutrition references report the approximate calcium content in milligrams per 8 oz (1 cup) for many foods.
Carrot juice, fresh 57
Fish, canned salmon eaten with bones 440
Fish, canned sardines or mackerel eaten with bones 569
Molasses, black strap 2820, 176.2 per tablespoon
Molasses, unsulphured 672, 42 per tablespoon
Sesame butter (unhulled sesame seeds) 1022, 63.9 per tablespoon
Sesame butter/ tahini from hulled or decorticated seeds 150 to 315.2, 10 to 19.7 per tablespoon
Soy beverage, unfortified 9.8
Soy beverage, calcium-fortified variable, check nutrition information; approx 200
Tofu, firm, prepared with calcium 1721
Tofu, regular, prepared with nigari, 260
Vegetarian support nutritional yeast, variable, check nutrition information
Dark green leafy vegetables Many dark green leafy vegetables have relatively high calcium concentrations. The calcium in spinach is however, somewhat poorly absorbed, probably because of the high concentration of oxalate. The study revealed that kale, a low-oxalate vegetable, is a good source of bio-available calcium. Kale is a member of the same family that includes broccoli, turnip greens, collard greens and mustard greens. These low-oxalate, calcium-rich vegetables are therefore also likely to be better sources of available calcium
cooked turnip greens 450
cooked bok choy 330
cooked collards 300
cooked spinach 250
cooked kale 200
cooked mustard greens 180
dandelion greens 150
romaine lettuce 40
head lettuce 10
Sea vegetables (seaweed)(dried powdered form)
agar-agar 1,000, 62.5 per tablespoon
Beans and Peas (cooked, ready to eat)
navy beans 140
pinto beans 100
garbanzo beans 95
lima, black beans 60
split peas 20
tapioca (dried) 300
brown rice, cooked 20
quinoa, cooked 80
corn meal, whole grain 50
rye flour, dark 40
tortillas, corn, calcium fortified (2) 120
tortillas, flour or unfortified (2) 23
whole wheat flour 50
raw oysters 240
salmon with bones 490
mackerel with bones 600
sardines with bones 1,000
hazelnuts (filbert) 450
sesame seeds (whole, unhulled) 2,100
sunflower seeds 260
The following herbs contain variable amounts of calcium:
borage, lamb's quarter, wild lettuce, nettles, burdock, yellow dock
Dried Herbs are rarely used in large portions, but consistently using some in your cooking will add calcium to the diet. Dried savory tops the list with 2132mg of calcium per 100g serving (213% daily need or DV), that is 85mg (9% DV) per tablespoon, and tastes great in bean dishes. Celery seed has 124mg (12%DV) of calcium per tablespoon, dried thyme has 57mg (6% DV) per tablespoon, dried dill has 53mg (5% DV) per tablespoon, dried marjoram has 40mg (4%DV) per tablespoon, dried rosemary has 38mg (4% DV) per tablespoon; sage, sisymbrium, oregano, spearmint, parsley, poppy seed, chervil and finally dried basil all make a mild showing with 21mg of calcium (2% DV) per tablespoon.
If you do not consistently get enough calcium from the food alone, consider using a calcium supplement. Take calcium supplements with meals, preferably in powder forms, for best absorption. Take enough calcium to make up the difference you are receiving from your diet and the following table, depending on your age group.
infants 600 mg/day.
children (up to 10 years old) 800 mg/day
teens 1200 mg/day
adults (to age 35) 1200 mg/day
adults (35-50) 1000 mg/day
post-menopausal women 1500 mg/day
The sources of calcium supplements include:
calcium asparginate, anhydrous highest amount of absorbable calcium per pill and does not require magnesium supplementation as the other supplements do.
calcium carbonate (Tums): highest amount of calcium per pill but may cause intestinal gas and/or constipation, and is poorly absorbed
calcium citrate: less calcium per pill but better absorbed than carbonate. No known side effects
calcium phosphate: already too much phosphorus in average diet so avoid this form
calcium lactate: The type of calcium in milk. Usually well absorbed, does not cause latose reaction in most people. Lactate is usually derived from lactic acid
calcium gluconate: Usually very well tolerated, easily absorbed. Can require many pills to get any amount of calcium
dolomite: bone meal may be contaminated with lead, know your supplier
1 Heaney RP, Weaver CM. Calcium absorption from kale. Am J Clin Nutr 1990; 51:656-657.