|reproduced from The Vegetarian Resource Group - URL: www.vrg.org/nutrition/calcium.htm - Credits|
Calcium, needed for strong bones, is found in dark green leafy vegetables, tofu made with calcium sulfate, and many other foods commonly eaten by vegans. High protein diets appear to lead to increased calcium losses. Calcium requirements for those on lower protein, plant-based diets may be somewhat lower than requirements for those eating a higher protein, flesh-based diet. However, it is important for vegans to eat foods regularly that are high in calcium and/or use a calcium supplement.
Tofu is commonly recommended as a good source of calcium. Actually, the amount of calcium in tofu depends on the coagulating agent used to precipitate the soy protein in the process of making tofu. Calcium sulfate and nigari (magnesium chloride) are two commonly used agents. The agent used will be listed on the label under ingredients. Tofu which is prepared with calcium sulfate will contain more calcium than tofu made with nigari.
The amount of calcium in tofu varies from brand to brand. To calculate how much calcium is in the tofu you buy, look at the label. Calcium content will be listed as percent of the Daily Value. Since the current Daily Value for calcium is 1000 milligrams, multiply the percent Daily Value by 10 to get the amount of calcium (in milligrams) in one serving. For example, tofu with 10% of the Daily Value for calcium would have 100 milligrams of calcium in one serving.
It is much more likely that protein intakes will be excessive on a meat-based diet or a diet high in dairy products as shown in Table 2. In addition, it appears that soy protein, even at high levels, does not increase calcium excretion the same way that protein from animal sources does . Diets which are too low in protein (around 44 grams a day) also appear to have a negative effect on calcium status . Sodium also increases calcium losses with 5 to 10 milligrams of calcium lost with each gram of salt eaten .
Calcium requirements for those on lower protein, plant based diets may be somewhat lower than requirements for those eating a higher protein, flesh-based diet. However, it is important for vegans to regularly eat foods high in calcium and/or use a calcium supplement.
We recommend that three or more servings of good sources of dietary calcium Table 1 be eaten daily by adults (4 or more servings for those age 51 and older), along with the use of a diet without excessive protein. Regular weight-bearing exercise such as walking, running, or aerobic dance is also recommended to promote strong, healthy bones. Table 3 shows several menus which contain more than 1000 milligrams of calcium.
Other factors which increase the risk of osteoporosis include small frame size, female gender, aging, heredity, cigarette smoking, excessive alcohol, Caucasian or Oriental race, steroid use, early menopause, prolonged immobilization, and inadequate vitamin D.
The most promising way that nutrition can reduce the risk of osteoporosis is by promoting development of a favorable peak bone mass during the first 3 to 4 decades of life. Several studies have shown that lacto-ovo vegetarians have the same [15-16] or larger  bone masses than do omnivores. We have little information about the bone health of vegans. A study which included 8 vegan women found that their bone density was not significantly from that of lacto-ovo vegetarians . A study of only 11 elderly vegan women found lower bone density in vegans although this may not be due to the vegan diet since some of the subjects had been vegan for only 2 years  . Further studies of bone mass of vegans of all ages are needed.
Food Amount Calcium (mg) Soy or ricemilk, commercial, 8 ounces 150-500 calcium-fortified, plain Collard greens, cooked 1 cup 357 Blackstrap molasses 2 Tbsp 342 Tofu, processed with calcium sulfate* 4 ounces 200-330 Calcium-fortified orange juice 8 ounces 300 Commercial soy yogurt, plain 6 ounces 250 Turnip greens, cooked 1 cup 249 Tofu, processed with nigari* 4 ounces 80-230 Kale, cooked 1 cup 179 Okra, cooked 1 cup 176 Soybeans, cooked 1 cup 175 Sesame seeds 2 Tbsp 160 Bok choy, cooked 1 cup 158 Tempeh 1 cup 154 Mustard greens, cooked 1 cup 152 Figs, dried or fresh 5 medium 135 Tahini 2 Tbsp 128 Almonds 1/4 cup 97 Broccoli, cooked 1 cup 94 Almond butter 2 Tbsp 86 Soymilk, commercial, plain 8 ounces 80*Read the label on your tofu container to see if it is processed with calcium sulfate or nigari.
Note: Oxalic acid, which is found in spinach, rhubarb, chard, and beet greens is often said to bind with calcium and reduce absorption. These foods should not be considered good sources of calcium. Calcium in other green vegetables, like kale, collard greens, Chinese mustard greens, and Chinese cabbage flower leaves is well absorbed.[10-11]. Fiber appears to have little effect on calcium absorption except for the fiber in wheat bran which does have a small effect 
Sources: Composition of Foods. USDA Nutrient Data Base for Standard Reference, Release 12, 1998. Manufacturer's information.
Food Amount Protein (gm) Cow's milk 8 ounces 8 Egg 1 6 Salmon, pink, canned 4 ounces 22 Beef, ground, lean, baked 4 ounces 27 Chicken, baked 4 ounces 37Adapted from Havala, S.: Osteoporosis, Beyond a Simple Answer. Vegetarian Journal 5:11, 1986.
Calcium (mg) Breakfast: 1 serving Cindy's Light and Fluffy Pancakes (p. 23) 195 1 cup Plain Soymilk 80 Lunch: 1 serving Hummus on Pita Bread (p. 27) 178 6 Dried Figs 162 1/4 cup Almonds 97 Dinner: 1 serving Scramble Tofu and Bok Choy over Brown Rice (P. 96) 190 1 serving Green Salad and Tangerine Dressing (p. 39) 30 1 serving Chocolate Pudding (p. 114) 92 --- TOTAL 1024 Breakfast: 1 serving Tropical Fruit Smoothie (p. 16) 102 1 toasted bagel with 66 2 Tbsp Almond Butter 86 Lunch: 1 serving Mini Pizzas (p. 34) 235 1 serving Creamed Spinach (p. 68) 121 Dinner: 1 serving Lemon Rice Soup (p. 46) 82 1 serving Tofu Squash Burgers (p. 102) 135 1 cup steamed Broccoli 94 with 1 Tbsp Sesame Seeds 80 --- TOTAL 1001Page numbers refer to recipes in the book Simply Vegan.
Additional foods should be added to these menus to provide adequate calories and to meet requirements for nutrients besides calcium.
2. Report on Health and Social Subjects: No. 41, Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. Report of the Panel on Dietary Reference Values of the Committee on Medical Aspects of Food Policy. London: HMSO, 1991.
3. Recommended Dietary Allowances for Japan. Tokyo, Japan: Ministry of Health and Welfare, 1991.
4. Recommended Daily Dietary Allowances, Korea. Kyongi, Korea: Ministry of Health and Social Affairs, 1989.
5. Zemel MB: Calcium utilization: Effect of varying level and source of dietary protein. Am J Clin Nutr 1988; 48: 880-883.
6. Kerstetter JE and Allen LH: Dietary protein increases urinary calcium. J Nutr 1990; 120: 134-136.
7. Linkswiler HM, Zemel MB, Hegsted M, Schuette S: Protein-induced hypercalciuria. Fed Proc 1981; 40: 2429-2433.
8. Heaney RP. Calcium: How your diet affects requirements. Veg Nutr and Health Letter Feb 1998; 1(3): 1-2.
9. Kerstetter JE, Caseria DM, Mitnick ME, et al. Increased circulating concentrations of parathyroid hormone in healthy, young women consuming a protein restricted diet. Am J Clin Nutr 1997; 66:1188-1196.
10. Weaver, CM, Plawecki KL: Dietary Calcium: adequacy of a vegan diet. AM J Clin Nutr 1994; 59 (Suppl.): 1238S-1241S.
11. Weaver CM, Heaney RP, Nickel KP, et al. Calcium bioavailability from high oxalate vegetables: Chinese vegetables, sweet potatoes, and rhubarb. J Food Sci 1997; 62: 524-525.
12. Weaver CM, Heaney RP, Martin BR, et al. Human calcium absorption from whole-wheat products. J Nutr 1991; 121: 1769-1775.
13. Feskanich D, Willet WC, Stampfer MJ, Colditz GA. Milk, dietary calcium, and bone fractures in women: A 12 year prospective study. Am J Public Health 1997; 87: 992-997.
14. Owusu W, Willett WC, Feskanich D, et al. Calcium intake and the incidence of forearm and hip fractures among men. J Nutr 1997; 127: 1782-1787.
15. Hunt IF, Murphy NJ, Henderson C et al: Bone mineral content in postmenopausal women: comparison of omnivores and vegetarians. Am J Clin Nutr 1989; 50: 517-523.
16. Marsh AG, Sanchez TV, Chaffee FL et al: Bone mineral mass in adult lacto-ovo-vegetarian and omnivorous males. Am J Clin Nutr 1983; 37: 453-456.
17. Marsh AG, Sanchez TV, Mickelsen O et al: Cortical bone density of adult lacto-ovo-vegetarian and omnivorous women. J Am Diet Assoc 1980; 76: 148-151.
18. Barr SI, Prior JC, Janelle KC, et al. Spinal bone mineral density in pre-menopausal vegetarian and nonvegetarian women: cross sectional and prospective comparisions. J Am Diet Assoc 1998; 98: 760-765.
19. Marsh AG, Sanchez TV, Michesen O, et al. Vegetarian life-style and bone mineral density. Am J Clin Nutr 1988; 48: 837-841.
|This article originally appeared in the book Simply Vegan: Quick Vegetarian Meals by Debra Wasserman. Nutrition section by Reed Mangels Ph.D., R.D. (ISBN 0-931411-20-3)|
January 15, 1999
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