Calcium Conundrum

An interview with Connie Weaver, Ph.D. Director, National Institutes of Health Botanical Center for Age-Related Diseases, Purdue University She is 54 years old, she is one of the world’s top experts on calcium, and she rarely takes a calcium supplement. “I don’t have to,” says Connie Weaver. “I drink plenty of milk.” While her three boys were growing up, the world-renowned researcher had one unwavering mealtime rule: milk for breakfast, lunch and dinner. Call her the dairy queen, but the old-fashioned dictum was a direct result of evolving research on a mineral that is clouded by confusion and misinformation. Weaver has masterminded studies that helped to form the most compelling advice yet for calcium intake in the world and in this country, where osteoporosis afflicts 25 million people. Much of her research at Indiana’s Purdue University has focused on children during their peak bone-growing years, between the ages of 12 and 15. The results, however, have implications for men and women of all ages. As the number of bone fractures escalates across the globe, Weaver has found herself invited to advise nations like Malaysia and Thailand, countries that only a few decades past dismissed osteoporosis as a Western disease. “About 60 percent of bone strength is determined by genetics,” Weaver says. “You can’t do anything about choosing your parents, but you can make a huge amount of difference in the other 40 percent with diet and exercise. My kids were such daredevils, they were constantly crashing and burning. I think their good bones saved them lots of problems.” Q: Is there a role for calcium in the body beyond bone strength? If you don’t maintain calcium in your body, you’ll die. Calcium is needed in every life process: it’s needed for your nerves to act, your muscles to contract, your brain to function, for practically every activity in the body. Ninety-nine percent of the body’s calcium is in the skeleton, and only 1 percent, concentrated in your blood, is used for all of those vital functions I just mentioned. Although it’s a small amount, the calcium in your blood must be maintained. So either you keep the blood replenished from your diet, or your body will take it from the big bank it has, the bones, because they are a lower priority. Q: How many of us get enough calcium? Over the age of about 11, people on average get only half of the calcium they need. Q: How does that calcium deficit affect most people? A deficiency in calcium doesn’t play out with an immediate consequence: you don’t get a canker sore, you don’t have a collapse right away. It plays out in later years, and often in the form of weakened bones. Look at the statistics: hip fractures occur in one out of every four Caucasian women over 50 and in one out of ten African-American women (who are the most protected genetically for having strong bones). Twenty percent of hip fractures occur in men, so they’re not immune. Twenty percent of people who have a hip fracture die because their lack of mobility harms their lungs and they get pneumonia. Q: Is it true that children are now suffering more bone problems? Bone fractures in children are tripling. There’s a vulnerable period at the start of your adolescent growth when you spurt up before your bones can fill in. Fractures are rising during this lag time when kids have relatively low bone density. Years ago it was more common to have milk with every meal: there wasn’t such a plethora of soda and other calcium-absent drink choices. Bone strength is also improved with weight-bearing exercise like walking, aerobics, basketball. But today people are much more sedentary, addicted to television and computer games. There’s one more factor: with the increase in childhood obesity, children are falling with greater force because of their weight, so the impact is higher. Q: Bone density is established during adolescence, but we can still influence bone strength later in life, right? After adolescence you can’t do very much more in building bone, just in preserving it. Hips finish growing first, about age 16. By the time you’re 17, you have 95 percent of your bone. Your spine is still pliable through college, up until the late twenties, 30. But at Purdue, we’re finding that sedentary women students are losing spine bone already. Others who exercise, drink milk or get other forms of dietary calcium continue to gain spine throughout that period. Q: What kind of exercise do you follow? I practice Aquacize [water aerobics] twice a week, circuit training when I can, and my vacations are active with skiing, hiking, etc. But I also wear a pedometer much of the time, take the stairs and practice other ways to get my daily 10,000 steps. Q: Can you get a daily dose of calcium from vegetables alone? Although calcium is well-absorbed from vegetables like bok choy, broccoli, kale and so forth, the amount you would need to eat is immense: the calcium in 21/4 cups of broccoli or nearly 5 cups of red beans rivals that in 1 cup of milk. Q: So how do you explain cultures that rarely eat dairy but have few problems with osteoporosis and hip fractures? If you have an Asian beside a Caucasian and they have equal bone density, the Caucasian will be more vulnerable on average to getting a fracture because their hip-bone length is longer. Asians’ geometry is such that if they fall, they’re much less likely to crack that shorter bone. There is nothing about diet that can change that. It’s an advantage that Asians have over Caucasians. Now to say that Asians don’t have a problem with osteoporosis isn’t my observation. Even though they’re protected by their bone geometry, they do have a problem, an increasing problem. In over a decade of reporting hip fractures in Hong Kong, researcher Edith Lau has seen the incidence triple. She attributes that to poor diet, low calcium and, ironically, to better overall nutrition that is causing the Asian population to get taller—consider the Chinese professional basketball players of today. Just like fat children, taller people fall harder on their bones and are more likely to break them with a harder impact. Q: Why do calcium needs change as we age? In my sixties will I need more calcium for those nerve actions? It’s not that the need for the biological activity of calcium changes, but the ability to utilize calcium for those activities changes. During adolescence, you absorb the most calcium and you excrete the least. About age 40, your efficiency starts declining so your calcium requirements go up to offset that deficiency. Q: Why does menopause make a difference? Estrogen suppresses calcium coming out of the bone, or bone resorption, so during menopause, all of a sudden you have an estrogen deficiency and resorption really escalates. You’re in this really rapid bone-loss period for the first few years after menopause, until your body readjusts, and then it sort of levels off on average to probably about 0.7 to 1 percent bone loss per year. Q: So someone age 55 is probably losing more than someone 65. Right, but then you go into another vulnerable period above age 80, when calcium efficiency declines again. Q: Do you think that the focus on calcium for women has shortchanged men? The research is way behind for men. Only recently have there been research trials in men and have we been able to make clinical guidelines for physicians working with men. But it’s still not in the practice of most physicians to even think, “Oh we should do a bone scan on an elderly man that comes in.” In many areas of the country, a man has to break a bone before anything is done. Q: Can we believe advertisements that suggest calcium can help in weight loss? The evidence isn’t strong enough to make a conclusion. I think there are good reasons to consume calcium, but research has yet to determine whether weight management is an important one. Q: Many people believe that protein leaches out calcium and thus milk isn’t a good source of calcium. It’s true that increasing protein increases calcium loss in urine, but that loss is offset by increased calcium absorption. So there’s no net disadvantage of extra protein in the diet. Q: If a person is not a fan of dairy, how do you suggest he or she get enough calcium? We have done a lot of work on different sorts of fortified foods, and many of them are as good as milk. Soymilk fortified with calcium carbonate is as good as milk as long as you shake it up to make sure the calcium gets into your mouth. Fortified orange juice seems to be quite a good substitute. If you can’t get enough of either dairy (which provides a package of nutrients needed for bone health including calcium, potassium, magnesium and vitamin D) or calcium-fortified foods, use supplements. Q: Can you overdose on calcium? There is an upper level of 2,500 milligrams (mg) per day, a level that is far above what you need. You just need to approach calcium with a little education. Don’t drink a quart of milk plus fortified cereal plus fortified juice plus a supplement. Healthy people excrete the extra calcium, but there are situations in which too much calcium can exacerbate renal problems and other conditions. Q: Do salty meals block calcium absorption? Every ion of sodium that a Caucasian excretes pulls out an ion of calcium with it. That can cause problems for bones. African Americans, on the other hand, retain a lot of sodium, which in adults can lead to high blood pressure. It does protect their bones, though, because they retain more calcium. Q: What about caffeine? We don’t know whether the calcium is coming from the bones or from the diet, but caffeine can increase the amount of calcium lost through urine. Some reports say that 2 to 4 tablespoons of milk will offset the effects of 5 cups of coffee. Lattes, for example, are good. Q: Do you have milk with every meal? My priority is milk with meals but that can’t always be accomplished. I’m 54, I need 1,200 mg calcium a day. I drink about two glasses of milk, giving me 600 mg, and in the rest of my diet—vegetables, cheese, fortified whole-grain cereal—I get another 400 to 600. I don’t take a supplement or even a multivitamin; I just try to follow the dietary guidelines. You ought to be thinking about a calcium source, a fruit, a vegetable and a whole grain at just about every meal to meet your dietary guidelines. —Allison J. Cleary