Calcium Q & A

Susan Whiting, PhD, Professor and Head, Division of Nutrition and Dietetics, College of Pharmacy and Nutrition, University of Saskatchewan, Canada has been studying the role of nutrition in osteoporosis and dietary factors affecting calcium utilization. Her studies have been published in the Journal of the Canadian Dietetic Association, Nutrition Research, Nutrition Reviews, American Journal of Clinical Nutrition and Journal of Bone and Mineral Research.Q: Is it ever too late to start getting enough calcium?A: While calcium needs to be in the diets of children and adolescents to maximize peak bone mass, calcium consumption is effective at any age. In fact, a study has just been published by Recker and colleagues in the Journal of Bone and Mineral Research1 in which elderly women (average age 75 years) benefited from extra calcium, especially women who had fractures. So it is never too late to benefit from getting enough calcium in your diet.Q: We know dairy products such as skim milk, nonfat yogurt and nonfat cheese are  good lowfat sources of calcium, but what about plant sources and their benefits?A: While we know that dairy products are a good source of calcium, plant sources of calcium are often overlooked.Perhaps too much emphasis was placed on spinach, which unfortunately is not a good source because the availability of calcium is low due to the oxalic acid content. Other green vegetables, such as broccoli, kale and Chinese cabbage are very available sources of calcium.It is important to have generous servings of these and other foods such as oranges, calcium-set tofu, canned salmon or sardines. The vegetarian pyramid recommends a tablespoon of blackstrap molasses a day for calcium. These are all wholesome foods providing other necessary nutrients;  moreover, the advantages of fruits and vegetables are to keep salt intake low and to provide an alkaline diet to balance the acidity of a diet high in animal protein.Another good reason to eat fruits and vegetables is that they contain the mineral boron. An early report2 found that a boron supplement was effective at reducing bone loss in postmenopausal women lacking estrogen. Some evidence suggests boron is helpful in calcium metabolism although more research needs to be done before supplements could be advocated.Q: What are your comments about increasing the RDA for calcium?A: It is very likely that the high calcium we recommend for North Americans (likely to be 1000 mg. for adults in the new RDAs and even up to 1500 mg. for seniors and teens) is because we do not have an optimal lifestyle in terms of physical activity and overall diet. National survey data shows that most people are not eating enough fruits and vegetables or getting enough exercise.There appears to be a minimum amount of calcium needed no matter what the diet is, but other factors in the diet such as salt, caffeine,  and high protein do require us to have even more calcium. And beyond diet, there are other factors like exercise, smoking and genetics that are very important.1Recker RR, et al. Correcting calcium nutritional deficiency prevents spine fractures in elderly women. J Bone Miner Res 11:1961-1966, 1996.2 Nielsen FH et al. Effect of dietary boron on mineral, estrogen and testosterone metabolism in postmenopausal women. FASEB J 1:394-397, 1987.Using Food Labels for Bone HealthThe Nutrition Facts panel on most food labels helps you select food products for optimum bone health.The amount of calcium in a given food product is given as a percent of Daily Value. The Daily Value of calcium for a 2000 calorie diet is 1000 mg. Therefore, if a food product says 10% of the DV for calcium, then it has 10% of 1000 mg or 100 mg of calcium in each serving.To be a fair source of calcium, a food has to have at least 5% of the DV 50 mg) for calcium for each 100 calories.Calcium TriviaHerbs  which contain >20 mg calcium per teaspoon include: fresh chervil, fresh spearmint leaves, dried basil, dill seed, dried oregano and dried thyme.Fruits which contain >30 mg calcium per serving: blackberries, boysenberries, dried figs, oranges and papayas.Vegetables which contain >30 mg calcium per serving: artichoke,  beet greens, bok choy, broccoli florets, cabbage, carrots, celery, chicory greens, dandelion greens, fennel, grape leaves, kale, kohlrabi, snow peas, red cabbage,  butternut squash, canned tomatoes and turnip greens.Source: Bone Appetit