Could your diet be robbing your body of calcium?
Confused about how to protect yourself from bone loss? Join the club. For decades, various news reports and marketing campaigns have emphasized calcium, leading many of us to believe that if we drink more milk and take more supplements, we might avoid calcium-related disorders. But projections of osteoporosis affecting more than 15 million people in the United States—one of the most prodigious consumers of milk products and dietary supplements in the world—belie the promise.
While there’s no doubt that calcium is a major player in bone health, many factors affect the mineral’s assimilation. Its presence in both food and supplements does not necessarily correlate to its bioavailability, and it is well known that only a portion of calcium consumed is absorbed. From some high-calcium foods, assimilation is estimated to be as low as 5 percent. Calcium requires a host of synergistic vitamins and minerals, many of which need to be in balance for proper assimilation. Vitamin D, magnesium, and boron top the list, but a dozen others are also contributors, and it is anticipated that more will be identified or discovered as the function of food constituents continues to be a trendy topic.
Most health-conscious people are aware that smoking and excessive alcohol intake, along with a lack of weight-bearing exercise and sun exposure, are significant factors in bone loss. Regardless, many still vacillate between healthy eating and the high-salt, high-sugar, coffee-quaffing culture that has put us, and our progeny, on a path to bone Armageddon. Few realize that overindulgence in meat, dairy, and even many favorite health foods may be imbalancing our bodies’ ability to assimilate calcium and other key minerals and nutrients. Excess protein, sugar, salt, and caffeine are all known calcium inhibitors, but so are excess phosphorus, phytic acid, and oxalic acid found in a wide range of foods beneficial to good health.
Moderation is the key. Balancing beans, whole grains, and other healthy foods with calcium, magnesium, boron, and other nutrients from a variety of fruits and vegetables can be another significant factor in calcium absorption. The resulting balanced diet has a much greater chance of providing necessary synergistic constituents.
Phosphorus is essential to calcium assimilation, but too much will inhibit its absorption. Because phosphorus is available in some amount in most foods, it is not surprising that most Americans consume too much to allow for optimum calcium utilization. Animal products such as meat, fish, dairy, and eggs are especially high, which casts a shadow on the popular high-protein diets. But the biggest threat comes from soda pop, which presents a triple whammy with phosphoric acid, high sugar, and empty calories. Healthy beans, nuts, and whole grains also contribute a large portion of phosphorus. A mere 1/4 cup of sunflower seeds supplies half of a day’s requirement, so balancing a wide variety of types of foods is very important.
Phytic acid, a component of whole grains, especially the bran portion, is another calcium inhibitor. Phytic acid combines with calcium and other minerals that are then excreted—but I wouldn’t recommend that you stop taking bran just yet. Bran is an excellent source of fiber, (which keeps you regular), and the role of phytic acid in reducing cancer-causing free radicals is currently under investigation. Getting your bran as a component of whole-grain foods provides a better balance of nutrients, but if you do take bran alone, don’t combine it with your calcium supplements.
Oxalic acid, another calcium inhibitor found in many high-calcium greens and other vegetables, provides perhaps the biggest conundrum. The extent to which oxalic acid inhibits calcium absorption is a hotly debated topic, with some sources saying that it is blown out of proportion, while others claim that it blocks the lion’s share of calcium.
Some foods most frequently cited for their calcium as well as high oxalic content include lamb’s-quarters, beet greens, almonds, and spinach. Also high in oxalic acid are star fruit, black pepper, tea, bananas, ginger, cashews, sorrel, mustard greens, and peppers. Although all of these foods proffer many health-giving constituents, you might not want to rely heavily on them if your main focus is on building bone.
Maintaining healthy bone structure is a complex topic, but striving for a “balanced diet, rich in calcium” tops the list of the National Osteoporosis Foundation’s recommendations for preventing osteoporosis. Here are some tips to achieve it.
1. Eat a varied diet of whole, natural foods for a synergistic complement of calcium, magnesium, boron, and a host of vitamins, minerals, and phytoconstituents, which contribute to healthy bone structure. Processed foods usually contain excessive amounts of salt and sugar plus flour that is stripped of vitamins and minerals, all of which interfere with calcium absorption. Vitamin D, another critical constituent, is available from a limited number of food sources, but the best source remains exposure to the sun.
2. Consider varied sources of calcium including a variety of high-calcium, low-phosphorus vegetables; reduced-fat dairy; and balanced supplements, but don’t overdo it. Excessive calcium inhibits absorption of other critical minerals. Although many foods contain calcium, discovering the best sources has never been easy. Milk has been touted as the panacea for decades, but some studies question the calcium assimilation and cite other health concerns. Green vegetables supply ample amounts of calcium and synergistic constituents, but detractors cite the large amount needed to meet daily values. Supplements may help fill in the gaps, but it can take a great deal of effort and education to find those that are balanced and can be assimilated.
3. Eat more cooked green vegetables, many of which are excellent sources of calcium, magnesium, and boron. Cooked greens actually provide more minerals because their reduced volume allows a person to consume significantly more than would be possible in raw form. Minerals are not affected by the heat of cooking. They can, however, leach into cooking water and be discarded. Collards, kale, bok choy, and broccoli are high in minerals, as are both black and green beans. Not all vegetables are as worthy as others when it comes to calcium assimilation. The nightshade family, which includes potatoes, tomatoes, and eggplant, is thought to negatively affect calcium absorption.
4. Add variety to your salads. Spicy, bitter greens such as arugula, cress, dandelion, chicory, and even nasturtium leaves and flowers are loaded with calcium. Celery, cucumber, and fennel all contain the big three: calcium, magnesium, and boron. Lettuce is high in calcium and boron. Most of the same greens and vegetables that are high in calcium, magnesium, and boron are excellent sources of beta-carotene, which converts to vitamin A in the body. Last year, a study in the Journal of the American Medical Association reported a 40 percent higher incidence of hip fractures in women who consumed high amounts of vitamin A from animal foods and supplements, which may reduce the body’s ability to utilize vitamin D. While this conclusion remains controversial, other studies have also suggested a correlation between the fat-soluble vitamin A and bone loss but no connection with the water-soluble beta-carotene, which is found in plant foods.
5. Drink more herb teas. When you’re thinking of all of those dark, leafy greens, include herbs. Red clover (Trifolium pratense), peppermint (Mentha ¥piperita), nettles (Urtica dioica), alfalfa (Medicago sativa), raspberry leaf (Rubus idaeus), chamomile (Matricaria recutita) and oatstraw (Avena sativa) are all high in calcium. Not only will these render numerous minerals and other constituents, but herbal teas are a good substitute for soft drinks and coffee whose sugar, phosphoric acid and caffeine are leading causes of calcium malabsorption.
6. Garnish heavily with culinary herbs, which also contain the big three and should be included as dark, leafy greens. Marjoram, summer savory, oregano, sage, parsley, rosemary, cumin, chervil, and tarragon are high in calcium. Cilantro and chives are loaded with magnesium. Parsley, cumin, marjoram, sage, and cilantro contain a good amount of boron, and basil; thyme, dill, and celery seed supply all three.
7. Make a few of your meals vegetarian and include some tofu in your diet. Various studies have shown that excessive protein, particularly from animal sources, inhibits calcium absorption. Not surprisingly, other reports refute this research, but teenage vegetarians reportedly start out with bone mass equal to omnivores but end up with significantly more as they age. Tofu is high in both calcium and phytoestrogens, which may help prevent bone loss, especially during menopause. All soy, however, does not provide equal amounts of calcium, and labels on soy products vary significantly. One soy yogurt manufactured with calcium carbonate listed 8 percent of the daily value of calcium per serving, while another of the same size manufactured with tricalcium phosphate claimed 50 percent. Tofu processed with calcium sulfate contains more calcium than other varieties.
8. Eat fruit in place of pastries and high-sugar desserts. Plums, strawberries, peaches, apples, and figs contain boron, which attracts calcium to the bone, making them a better choice than calcium inhibitors such as high-sugar confections.
9. Try using kelp and herb blends instead of table salt. Kelp contains calcium and magnesium but is low in phosphorus. It does, however, contain a high percentage of sodium, so large amounts are not recommended.
10. Embrace the great outdoors. Dietary availability of vitamin D, a critical component of calcium absorption, is limited. Sources include bee products, mushrooms, alfalfa sprouts, sunflower seeds, basil, raspberry leaf and watercress, but the most reliable and readily available source for most people is still some exposure to the sun.
Debbie Whittaker, the Herb Gourmet, is a culinary herbalist and instructor.
National Osteoporosis Foundation
Osteoporosis and Related Bone Diseases National Resource Center
1232 22nd St. NW
Washington, D.C. 20037
The Weston A. Price Foundation’s “Myths and Truths About Osteoporosis,”
Plants for a Future
Agricultural Research Service
Various branches and entities, including www.ars-grin.gov
Journal of the American Medical Association
Women’s Bodies, Women’s Wisdom
by Christiane Northrup, M.D. (Bantam, 1998)
Nutrition for the 21st Century
by William L. Kyle, N.D. (Kyle, 1995)
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