All the world is nuts about
Almost Everything You Want To Know
And Are Not Afraid To Ask
Tell someone you are vegan, and invariably the first question you are asked is "How do you get your protein?" If you have not already discovered it, we have simplified your response by providing answers to that query in our Protein Basics.
Most likely, the second frequently asked question you'll hear is "If you don't eat dairy products, how do you get enough calcium?" In this article we endeavor to present common questions about calcium in the diet. Each question is answered with a quotation or quotations from those we consider reliable sources like physicians, dieticians, and researchers.
If after reading this article you find a dietary calcium question we have not addressed, send it to us so that we can research the answer and include it in this article.
Q: What is calcium?
A: "Calcium is a mineral that the body needs for numerous functions, including building and maintaining bones and teeth, blood clotting, the transmission of nerve inpulses, and the regulation of the heart's rhythm. Ninety-nine percent of the calcium in the human body is stored in the bones and teeth. The remaining 1 percent is found in the blood and other tissues."
A: "The body gets calcium it needs in two ways. One is by eating foods that contain calcium. Good sources include dairy products, which have the highest concentration per serving of highly absorbable calcium, and dark leafy greens or dried beans, which have varying amounts of absorbable calcium.
"The other way the body gets calcium is by pulling it from bones. This happens when the blood levels of calcium drop too low, usually when it's been a while since having eaten a meal containing calcium. Ideally, the calcium that is 'borrowed' from the bones will be replaced at a later point. But, this doesn't always happen. Most important, this payback can't be accomplished simply by eating more calcium."
A: According to the Office of Dietary Supplements of the National Institutes of Health, the amount needed varies by age group but not by sex. The chart below contains their recommendations:
Source: Office of Dietary Supplements, NIH Clinical Center, National Institutes of Health
Dr. John McDougall takes a different view. He writes, "Studies have shown that an intake of 150 to 200 mg of calcium daily is adequate to meet the needs of most people, even during pregnancy and lactation. And in fact, most of the world's population injests 300 to 500 mg of calcium each day. Calcium is so efficiently absorbed by the human intestine and so sufficient in diets of mankind, that calcium deficiency of dietary origin is unknown in human beings.
"Only in those places where calcium and protein are eaten in relatively high quantities does a deficiency of bone calcium exist at such epidemic rates, due to an excess of animal protein."
A: According to a Continuing Survey of Food Intakes of Individuals conducted by the US Department of Agriculture between the years 1994 and 1996, the following percentage of Americans did not meet the recommended intake for calcium:
A: Dr. Holly Roberts says, "If you have a calcium deficiency, you may develop twitching, nerve sensitivity, brittle nails, insomnia, depression, numbness, and heart palpitations. Painful muscle cramps in the calves may occur often during pregnancy, particularly in women who are deficient in calcium."
A: Dr. Walter Willett says, " Milk is clearly the most efficient way to get calcium from food, since it delivers almost 300 mg per eight-ounce glass. Few other foods come close to packing in that much calcium. But milk delivers more than just calcium, and some of its other components--like extra calories, saturated fat, and the sugar known as galactose--aren't necessarily good for you. What's more, as many as 50 million adults in the United States can't completely digest the milk sugar known as lactose. Nor can most of the world's population.
"Dairy products shouldn't occupy the prominent place that they do in the USDA Pyramid, nor should they be the centerpiece of the national strategy to prevent osteoporosis. Instead, the evidence shows that dietary calcium should come from a variety of sources and, if more calcium is really needed, from cheap, no-calorie, easy-to-take supplements. Then you can look at dairy products as an optional part of a healthy diet and take them in moderation, if at all."
Dr. Willett adds, "If no one really knows the best daily calcium target, then why not play it safe and boost your calcium by drinking three glasses a day? Here are five good reasons: lactose intolerance, saturated fat, extra calories, a possible increased risk of prostate cancer, and a possible increased risk of ovarian cancer." Source: Eat, Drink, and Be Healthy, 144
Dr. Neal Barnard writes, "Dairy products contain sex hormones, too. Farmers keep dairy cattle pregnant virtually constantly. This keeps their milk production high. The hormones circulating in a pregnant cow's blood easily pass into her milk. In fact, one of the ways farmers test whether their cows are pregnant or not is to measure estrogens in their milk. You cannot taste them, but they are there. These hormones end up in milk regardless of whether the farmer gives extra hormones to the cow; the cow makes them herself and they go straight into her milk. Several population studies have shown a correlation between dairy product consumption and breast cancer incidence."
Dr. Fuhrman says, "Hip fractures and osteoporosis are more frequent in populations in which dairy products are commonly consumed and calcium intakes are commonly high. For example, American women drink thirty to thirty-two times as much cow's milk as the New Guineans, yet suffer forty-seven times as many broken hips. A multicountry analysis of hip-fracture incidence and dairy-product consumption found that milk consumption has a high statistical association with higher rates of hip fractures."
Dr. T. Colin Cambell says: "Americans consume more cow's milk and its products per person than most populations in the world. So Americans should have wonderfully strong bones, right? Unfortunately not. A recent study showed that American women aged fifty and older have one of the highest rates of hip fractures in the world. The only countries with higher rates are in Europe and in the South Pacific (Australia and New Zealand) where they consume even more milk than the United States."
Dr. Fuhrman states, "There are many good reasons not to consume dairy. For example, there is a strong association between dairy lactose and ischemic heart disease. There is also a clear association between high-growth-promoting foods such as dairy products and cancer. There is a clear association between milk consumption and testicular cancer. Dairy fat is also loaded with various toxins and is the primary source of our nation's high exposure to dioxin. Dioxin is a highly toxic chemical compound that even the U.S. Environmental Protection Agency admits is a prominent cause of many types of cancer in those consuming dairy fat, such as butter and cheese. Cheese is also a power inducer of acid load, which increases calcium loss further. Considering that cheese and butter are the foods with the highest saturated fat content and a major source of our dioxin exposure, cheese is a particularly foolish choice for obtaining calcium."
A: Dr. Holly Roberts says, "Calcium deficiency can occur, not only if your diet is low in calcium, but also if your diet is high in phosphorus. The ratio of calcium to phosphorus in your bones is 2.5 to 1. If your diet includes higher levels of calcium than phosphorus, it is more likely that you will maintain this healthy ratio and healthy bones. To do this, it is best if you maintain a ratio of phosphorous to calcium within your diet of 1:1. The diet of many Americans contains a phosphorous-to-calcium ratio of 4:1. Calcium is a positive ion, which means it will bind with negative ions. Foods that contain phosphorus form negative ions. So if you have excess phosphorus in your diet, it will bind calcium to it and you will excrete both of these minerals. If such a situation develops, you may actually lose more calcium than you took in, and you will deplete the calcium stored in your bones. Phosphorus is present in carbonated drinks, meat, eggs, and cheese spreads.
"You will absorb higher levels of calcium if your diet contains adequate amounts of vitamin D, magnesium, dairy products, and vitamin C. Regular exercise helps the body absorb calcium. However, if you follow a high-fat or high-protein diet that is rich in phosphorus, it will be more difficult for your body to absorb calcium."
A: The Linus Pauling Institute at Oregon State University states, "Abnormally elevated blood calcium (hypercalcemia) resulting from the over consumption of calcium has never been documented to occur from foods, only from calcium supplements. Mild hypercalcemia may be without symptoms, or may result in the loss of appetite, nausea, vomiting, constipation, abdominal pain, dry mouth, thirst, and frequent urination. More severe hypercalcemia may result in confusion, delirium, coma, and if not treated, death. Hypercalcemia has been reported only with the consumption of large quantities of calcium supplements usually in combination with antacids, particularly in the days when peptic ulcers were treated with large quantities of milk, calcium carbonate (antacid) and sodium bicarbonate (absorbable alkali). The condition was termed milk alkalai syndrome, and has been reported at calcium supplement levels from 1.5 to 16.5 grams/day for 2 days to 30 years. Since the treatment for peptic ulcers has changed, the incidence of this syndrome has decreased considerably.
A: Registered dieticians Vesanto Melina and Brenda Davis write:
"Because calcium needs are influenced by a host of factors, it is extremely difficult for nutrition experts to determine exactly how much calcium an individual needs to function at optimum levels and to continue into old age with healthy, strong bones. In fact, it has been such a challenge that the recommendations are now called 'Adequate Intakes' (AI) and are a sort of 'best guess,' used when there is insufficient data to make a firm recommendation. These Adequate Intakes may seem high. Remember that they are based on the needs of the general North American population, with high amounts of sodium and meat-centered diets providing much more protein than needed. To make things worse, the population is largely sedentary, a factor that works against the retention of minerals in bones.
"It is possible that the calcium requirements of vegans and of other vegetarians are lower than the general population, particularly if:
"However, note that salt, tamari, and miso are vegan food ingredients. Though plant proteins are somewhat lower in sulfur-containing amino acids, vegans should not assume they are protected from osteoporosis because of lower protein intakes." Source: Becoming Vegan, 95
Melina and Davis point out, "On average, North Americans absorb about 30% of the calcium that is present in our diets, but when you take into account the amounts lost in urine and feces, the actual amount we retain may be as low as 10% of what was in our food. From the calcium that makes its way into our bodies, there can be substantial losses, depending on certain characteristics of our diet, particularly the protein and sodium contents. A single fast food hamburger could result in calcium losses of about 23 mg. However, if we retain only 10% of what was in our diet, that one burger would, in effect, increase dietary calcium needs by 230 mg."
Dr. John McDougall says: "Humans have a highly efficient intestinal tract that, under almost every circumstance, will absorb the correct amount of calcium to meet the body's needs. The intestinal cells act as regulators for the amount of calcium that enters the body. When the calcium content of the diet is low, a relatively higher percentage of calcium will be absorbed from the foods. If the diet is high in calcium, a smaller percentage of the calcium will be absorbed. But the body's need is always the controlling factor regulating the entry of calcium into the cells of the intestinal wall."
A: Dr. Fuhrman provides the following list:
Dr. Neal Barnard provides his list:
Davis and Melina say, "When the kidneys excrete excess sodium, 23 to 26 mg of calcium is lost along with every gram of sodium excreted."
A: Dr. Neal Barnard explains: "A meat-based diet is disastrous for bones. Switching from beef to chicken or fish does not help because these products have as much animal protein as beef or even a bit more. Bodybuilders and others who take protein supplements have even greater calcium losses. The problem is not just the amount of protein in meats but also the type. Meats are loaded with what are called sulfur-containing amino acids, which are especially aggressive at causing calcium to be lost in the urine."
In looking at calcium loss, Dr. Joel Fuhrman states, "Published data clearly links increased urinary excretion of calcium with animal-protein intake but not with vegetable-protein intake. Plant foods, though some may be high in protein, are not acid-forming. Animal-protein ingestion results in a heavy acid load in the blood. This sets off a series of reactions whereby calcium is released from the bones to help neutralize the acid. The sulfur-based amino acids in animal products contribute significantly to urinary acid production and the resulting calcium loss. The Nurses Health Study found that women who consumed 95 grams of protein a day had a 22% greater risk of forearm fracture than those who consumed less than 68 grams."
Dr. Dean Ornish says, "The real cause of osteoporosis in this country is not insufficient calcium intake, it's excessive excretion of calcium in the urine. Even calcium supplementation is often not enough to make up for the increased calcium excretion. Vegetarians, in contrast, excrete much less calcium, and this is why they have very low rates of osteoporosis even though their dietary intake of calcium is lower than those on a meat-eating diet."
A: "Dairy products are not the healthiest source," says Dr. Neal Barnard. "They do contain calcium, but only about 30% of it is absorbed. The remaining 70% never makes it past the intestinal wall and is simply excreted with the feces. Dairy products have many other undesirable features, including animal proteins that contribute to some cases of arthritis and respiratory problems, lactose sugar that is linked to cataracts, frequent traces of antibiotics, and other problems that lead many doctors to suggest that we avoid them and get calcium from healthier sources.
"The healthiest calcium sources are 'greens and beans.' Green leafy vegetables are loaded with calcium. One cup of broccoli has 178 milligrams of calcium. What's more, the calcium in broccoli and most other green leafy vegetables is more absorbable than the calcium in milk. An exception is spinach, which has a form of calcium that is not well absorbed."
"Beans, lentils, and other legumes are also loaded with calcium. We think of beans as a humble food, but they are an extraordinary source of nutrition. They have calcium, omega-3 fatty acids, the cholesterol-lowering soluble fiber that many people thought was only in oat bran, and healthy complex carbohydrates. If you make green vegetables and beans regular parts of your diet, you'll get two excellent sources of calcium."
Dr. Fuhrman agrees by writing, "You do not need dairy products to get sufficient calcium if you eat a healthy diet. All unprocessed natural foods are calcium-rich; even a whole orange (not orange juice) has about 60 mg of calcium."
Dr. John McDougall says, "A vegetable-based diet is rich in calcium and all the other nutrients the body needs. Let's not forget that the original source of all calcium is the earth, and plants make this mineral available to animals, including humans, in delicious, digestible packages. That's where all the animals get it and you can, too."
A: Dr. Charles Attwood says, "Infants fed whole cow's milk have low intakes of iron, linoleic acid, and vitamin E, and excessive intakes of sodium, potassium, and protein, illustrating the poor nutritional compatability of solid foods and whole cow's milk.
"Whole cow's milk displaces some and, in many cases, most solids in this age group. I regularly find children in my practice over the age of 1 year who consume up to a half-gallon of cow's milk daily and barely any solids at all. This leads to respiratory allergies, obesity, iron deficiency anemia, and, not least of all, elevated cholesterol levels due to the excess of saturated fat."
Dr. John McDougall says, "Dairy protein can cause severe constipation. A 1998 study published in the New England Journal of Medicine looked at sixty-five severely constipated children averaging only one bowel movement every three to fifteen days. Though these children did not respond to strong laxatives (lactulose and mineral oil), forty-four of the sixty-five (68%) found relief of their constipation by removing cow's milk from their diet. Related problems, such as inflammation of the bowel, anal fissures, and pain, were all resolved as well with the elimination of cow's milk. When cow's milk was reintroduced into their diet eight to twelve months later, all of the children redeveloped constipation within five to ten days."
A: In Becoming Vegan the authors write, "Vitamin D is a major player in a team of nutrients and hormones that keep blood calcium at optimal levels and support bone health during growth and throughout life. It stimulates the absorption of the bone-building minerals calcium and phosphorus from the intestine and helps regulate the amount of calcium in bone. It is important for proper functioning of cells throughout the body (in muscle, nerves, and glands) that depend on calcium. If more blood calcium is needed, vitamin D is able to act in three places:
A: Dr. Walter Willett writes, "Until recently, vitamin K was thought to be necessary mostly for the formation of proteins that regulate blood clotting. It turns out, though, that this fat-soluble vitamin also plays one or more roles in the regulation of calcium and the formation and stabilization of bone. So too little vitamin K may help set the stage for osteoporosis. In the Nurses' Health Study, women who got more than 109 micrograms of vitamin K a day were 30 percent less likely to break a hip than women who got less than that amount. Vitamin K is mainly found in green vegetables such as dark green lettuce, broccoli, spinach, Brussels sprouts, and kale. Eating one or more servings of these foods a day should give you enough vitamin K.
*All items vegan
*Oxalates prevent the complete absorption of calcium.
*Oxalates prevent the complete absorption of calcium.
About the Experts
Dr. Neal D. Barnard is an adjunct associate professor of medicine at George Washington University of Medicine and president of the Physicians Committee for Responsible Medicine, a nonprofit organization that promotes preventive medicine, conducts clinical research, and encourages tougher standards for ethics and effectiveness in research. He is the author of numerous books including Foods That Fight Pain, Dr. Neal Barnard's Program for Reversing Diabetes, Breaking the Food Seduction, Turn Off the Fat Genes, and Eat Right, Live Longer.
Dr. T. Colin Campbell is a Jacob Gould Schurman Professor Emeritus of Nutritional Biochemistry at Cornell University. He has been a nutritional researcher for over 40 years and served as director of the China Study, the most comprehensive study of diet, lifestyle, and disease ever done with humans in the history of biomedical research. The New York Times described the project as the "Grand Prix of Epidemiology."
Brenda Davis is a registered dietitian and co-author of Becoming Vegetarian. and Becoming Vegan. Her other books include Dairy-free, and Delicious, Defeating Diabetes and The New Becoming Vegetarian. She is a past chairperson of the Vegetarian Nutrition Dietetic Practice Group of the American Dietetic Assocation.
Dr. Joel Fuhrman is a board-certified family physician who specializes in preventing and reversing disease through nutritional and natural methods. He devotes his career to applying the comprehensive body of scientific literature that establishes that disease has known nutritional and environmental causes. Dr. Fuhrman is the author of Eat to Live, Fasting and Eating for Health, and Disease-Proof Your Child.
Dr. John McDougall is certified as an internist by the Board of Internal Medicine and the National Board of Medical Examiners. He is a renowned physician and researcher, lecturer, radio and television personality, and author of numerous best-selling health books like The McDougall Plan: 12 Days to Dynamic Health, McDougall's Medicine: A Challenging Second Opinion, The McDougall Program for Maximum Weight Loss, The New McDougall Cookbook, The McDougall Program for Women, and The McDougall Program for a Healthy Heart. Dr. McDougall is the founder and medical director of the nationally renowned McDougall Program, a ten-day, residential program located at a luxury resort in Santa Rosa, California.
Vesanto Melina is a registered dietitian and co-author of Becoming Vegetarian. and Becoming Vegan. She coordinated the vegetarian section of the Manual of Clinical Dietetics, 6th edition, a joint project of the American Dietetic Association and Dietitians of Canada. She has taught nutrition at University of British Columbia and Bastyr University.
Dr. Dean Ornish is the founder, president, and director of the non-profit Preventive Medicine Research Institute in Sausalito, California, where he holds the Bucksbaum Chair. He is Clinical Professor of Medicine at the University of California, San Francisco. For the past 25 years, Dr. Ornish has directed clinical research demonstrating, for the first time, that comprehensive lifestyle changes may begin to reverse even severe coronary heart disease, without drugs or surgery. He is the author of five best-selling books, including New York Times' bestsellers Dr. Dean Ornish's Program for Reversing Heart Disease, Eat More, Weigh Less, and Love & Survival. He recently directed the first randomized controlled trial demonstrating that comprehensive lifestyle changes may affect the progression of prostate cancer.
Dr. Holly Roberts is board certified in obstetrics and Gynecology and Pathology. She has advanced fellowship training in cancer surgery and is a cofounder of a nonprofit series on health and wellness.
Dr. Walter C. Willett is a Frederick John Stare Professor of Epidemiology and Nutrition and chairman of the Department of Nutrition at the Harvard School of Public Health and a professor of medicine at the Harvard Medical School. A world-renownd researcher, he is one of the leaders of the famous Nurses' Health Study and Health Professionals Follow-up Study.
Attwood, Charles R. Dr. Attwood's Low-Fat Prescription for Kids. New York: Viking, 1995.
Barnard, Neal. Eat Right, Live Longer: Using the Natural Power of Foods to Age-Proof Your Body. New York: Harmony Books, 1995.
Campbell, T. Colin with Thomas M. Campbell II. The China Study: Startling Implications for Diet, Weight Loss and Long-Term Health. Dallas, Texas: Benbella Books, 2004.
Davis, Brenda and Vesanto Melina. Becoming Vegan: the Complete Guide to Adopting a Healthy Plant-based Diet. Summertown, Tennessee: Book Publishing Co., 2000.
Fuhrman, Joel. Eat to Live: The Revolutionary Formula for Fast and Sustained Weight Loss. Boston: Little Brown, 2003.
Harvard School of Public Health. "Calcium & Milk." http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/calcium-full-story/#where
Linus Pauling Institute at Oregon State University. "Calcium." http:lpi.oregonstate.edu/infocenter/minerals/calcium
McDougall, John A. Dr. McDougall's Digestive Tune-Up. Summertown, Tennessee: Healthy Living Publications, 2006.
McDougall, John A. Recipes by Mary McDougall The McDougall Program for a Healthy Heart: a Life Safing Approach to Preventing and Treating Heart Disease. New York: Dutton, 1996.
National Institutes of Health Office of Dietary Supplements. "Dietary Supplement Fact Sheet: Calcium." Source: http://dietary-supplements.info.nih.gov/factsheets/calcium.asp
The NutriBase Nutrition Facts Desk Reference. New York: Avery, 2001.
Ornish, Dean. Dr. Dean Ornish's Program for Reversing Heart Disease: the Only System Scientifically Proven to Reverse Heart Disease Without Drugs or Surgery. New York: Ballantine Books, 1990.
Roberts, Holly. Your Vegetarian Pregnancy: a Month-by-Month Guide to Health and Nutrition. New York: Simon & Schuster, 2003.
USDA National Nutrient Database for Standard Reference http://www.nal.usda.gov/fnic/foodcomp/search/
Willett, Walter C. Eat, Drink and Be Healthy: the Harvard Medical School Guide to Healty Eating. New York: Simon & Schuster, 2001.