Q: I know I need to get more calcium in my diet because my diet is pretty bad. I don’t exercise much, and I’ve always been on the thin side, so I guess I could be at risk for osteoporosis. If I’m taking a multivitamin with calcium in it, do I really need to take a separate calcium supplement too?
Calcium is bulky, so there is no way to fit a day’s supply in a multivitamin. Most multivitamins have, at most, 100 to 200 mg of calcium — much less than the 1,000 to 1,200 mg you need. So, yes, you really should be taking a separate calcium supplement. But if you radically change your diet, you may be able to get enough calcium from diet alone. Start counting your servings of high-calcium foods. If you consistently eat at least three servings of a high-calcium food every day, you’re probably safe. But if your diet is erratic, as you suggest, then take 500 to 600 mg of calcium with D3 once a day either in the morning or afternoon. By the evening, think back to how you ate during the day: If you ate two or more servings of a high calcium food, then you can skip the evening dose. If not, take an additional 500 to 600 mg with a snack before bed. (However, if you have been diagnosed with osteoporosis or osteopenia, always follow your doctor’s instructions, which may be to take the second dose of calcium regardless of how much calcium you’ve consumed from food .) Your body can only absorb about 500 mg calcium at one time, so if you require a large amount, it’s important to split your calcium into two daily doses rather than taking 1,000 to 1,200 mg in a single tablet. If you find that taking calcium supplements causes constipation, try taking a supplement that includes magnesium (as well as Vitamin D). The magnesium acts as a gentle laxative and helps keep you regular.