Ah, nutrient controversies. Where would we be without them? Take the current shifting of the winds over calcium.
We really need structurally sound skeletons, that’s for sure. So, like every other disease on the planet, we should take steps to avoid osteoporosis, which affects about twice as many women as men. But does that mean popping calcium pills daily? Who knows? Problem is, opinions are rapidly shifting as breakthrough info (soon to be passé) on vitamin D starts altering researchers’ mindsets. The bottom line on bone protection is don’t assume that what you heard five years ago still counts.
What the experts say
“Most adults need about 1,000 mg of calcium a day. More is recommended if you’re over 50. Just how much more isn’t really known, and the reason I’m less certain than I might have been is that we’re changing our ideas about vitamin D. It may be that if you have adequate vitamin D, you can do without the extra calcium. We’d always said that pregnant women need more calcium, and then we realized that all the hormones in pregnancy actually make absorption more efficient. Magnesium is important, but there’s no need to take it with calcium. If you eat a good diet, you get magnesium from all the food groups. Some of the [anti-milk] groups promote misinformation. It’s been proven through rigorous testing that people absorb the calcium in milk very well. Very high levels of calcium – for example, if you’re eating a roll of Tums or Rolaids every day – can cause kidney damage. It can affect your vascular system, too. Kidney stones are another problem.”
SUSAN WHITING, professor of nutrition, University of Saskatchewan, Saskatoon
“People used to think taking too much vitamin D would make you absorb too much calcium, but there is a threshold point where your calcium absorption efficiency doesn’t get any higher. Because people have been relatively vitamin-D-deficient, the compensation has been to take more calcium. My contention is, if you had enough vitamin D, you wouldn’t need as much calcium, but nobody has done that kind of clinical trial. There’s a difference between theory and reality. The milk industry is not going to fund research to figure out whether you can get away with drinking less milk. Companies pretend there’s a difference [between brands of calcium supplements], but the reality is there isn’t.”
REINHOLD VEITH, department of nutritional sciences, faculty of medicine, U of T
“The typical Western diet of cereal grains (wheat, rice, barley, corn, oats), meat and fish is net acid-producing. This affects the way the kidneys handle calcium, so you get increased calcium excretion. The body has many mechanisms for buffering and neutralizing acid, but they’re not perfect. So, if you habitually eat a net acid-producing diet, you’ll always have some acid floating around, chewing up your calcium. We found experimentally that if you neutralize the acid in the diet, calcium excretion in the urine goes way down. Take adequate amounts of vitamin D and eat a diet more like that of our pre-agricultural ancestors.”
ANTHONY SEBASTIAN, MD, professor of medicine, University of California, San Francisco
“A study in the UK looked at close to 35,000 people – meat eaters, fish eaters, vegetarians and vegans. Vegans had about 1.3 times more fractures than the non-vegetarians. But once researchers controlled for calcium, the vegans did as well as or better than the others. Soy milk has calcium levels similar to those in cow’s milk – 32 per cent in cow’s and 25 per cent in soy. You need to be really picky about which green vegetables to eat. Some have almost no calcium. Spinach, beet greens and Swiss chard contain oxalic acid, which prevents the absorbtion of calcium. You absorb 40 to 70 per cent of the available calcium (higher than milk) from broccoli, kale and mustard greens. Tofu is another source, but you have to check the amount of calcium sulphate on the label. Another source is legumes. Two tablespoons of blackstrap molasses has about the same amount of calcium as a cup of milk.”
BRENDA DAVIS, dietitian, author, Becoming Vegetarian, Becoming Vegan, Kelowna, BC
