Counting Calcium: Don’t Forget Foods

Beth Kitchin, PhD, RD
Assistant Professor
UAB Department of Nutrition Sciences

                

    Much of my work as the patient educator in the UAB Osteoporosis Prevention and Treatment Clinic involves counseling patients on calcium and vitamin D supplements and osteoporosis medications. While some patients are not getting enough calcium, some are actually over-supplementing. Somehave been told by their doctors or other health professionals to make sure to take several calcium tablets a day to achieve 1000 to 1500 mg of calcium a day.  But there are some problems with this one-size-fits-all advice:

Ø  Some patients are also getting calcium from their foods. If a patient drinks milk, eats yogurt, cheese, or calcium added orange juice, soy, or almond milk, she or he could be getting at least some of their daily dose of  calcium from these dietary sources.

Ø  Patients may be taking a multivitamin that has quite a bit of calcium in it. Many women’s multivitamins have as much as 500 mg of calcium in one tablet. That’s as much and sometimes more calcium than many calcium supplements.

Ø  Calcium supplements vary in serving size and amount of calcium. If you’ve ever looked at the supplement section in the grocery or drug store you were likely overwhelmed by the sheer number and types of calcium supplements. Add to that the internet shopping options and you’ve got a lot of confusion on both the part of the patient and the clinician.  The amount of calcium shown on the label is for the specific serving size specified on the label. I’ve seen serving sizes on various supplements range from one to six tablets. Patients are often unaware that they need to check the serving size first.

Ø  Excessive calcium is unnecessary and may be harmful. The upper limit for calcium intake is 2000 to 2500 mg a day for adults, depending upon age. Excessive calcium can cause constipationand may lower the absorption of other nutrients although this is not well established.

Ø  To make matters even more confusing, a few supplements like some versions of Tums show you how much calcium carbonate is in the tablet as opposed to just elemental calcium, which is what patients really need to know.  To figure out the elemental calcium you need to know that calcium carbonate is 40% elemental calcium and do the math.  Calcium citrate is 21% elemental calcium but I have not seen any supplements that show the total amount of calcium citrate on the label so this does not seem to be an issue with calcium citrate supplements.

                Because of these issues, patients and clinicians often miscalculate the amount of calcium the patient is getting.I find that a quick dietary assessment of a few key foods that are high in calcium is useful.I ask the patient if she or he eats or drinks the following foods most (5 to 7) days of the week:

Ø  Milk, soy or almond milk, calcium-added orange juice (~300 mg calcium per                                         cup).

Ø  Cheese (~200 mg calcium ounce).  A typical piece of pre-sliced cheese is usually                                                one ounce.  Three dominoes can be used to visualize an ounce of cheese as well.

Ø  1 small carton of yogurt (200 – 300 mg calcium)

Ø  Liquid supplements like Ensure, Boost, or SlimFast (~300 mg of calcium per can)

               

  Answers to these questions give me a rough estimate of how much calcium a patient is getting on an average day.  I then assess how much calcium the patient is getting from their supplements – including multivitamins. This can be a bit challenging if the patient has not brought his or her supplements to their appointment!  I also ask patients if they take Tums for stomach upset. I find that sometimes patients take Tums regularly but do not think of them as a calcium supplement. I then adjust their supplements if necessary.

 

                 I also recommend that patients spread their calcium dose out throughout the day – preferably to three times a day – stressing that foods count as a “dose”. We typically recommend not more than 500 to 600 mg of calcium at one time since fractional absorption begins to decrease after that amount. Research also suggests that split dosing of calcium can help keep parathyroid levels from spiking throughout the day.  I also recommend that patients take calcium carbonate supplements with food since calcium carbonate needs stomach acid for absorption. Right before a meal or within 30 to 40 minutes later should suffice.

                Fortunately, estimating vitamin D intake is much simpler than estimating calcium intake. Since few foods are high in vitamin D and most older patients won’t make enough from UVB rays due to lower levels of 7-dehydrocholesterol in aging skin, simply adding up the total vitamin D from over-the-counter supplements will give you a good estimate of the patient’s  intake. I usually recommend a daily dose of 1000 to 2000 IU’s from over-the- counter supplements to maintain healthy blood levels of vitamin D. Patients who take both a multivitamin and a calcium +D supplement may not need an additional vitamin D supplement. Separate vitamin D supplements are easy to find and come in a variety of doses. Spit dosing is unnecessary since vitamin D is fat-soluble. Some research shows that taking it with food improves absorption.

                Helping patients understand how to get the right amount of calcium from foods and supplements can be challenging.  However, we can help our patients supplement sensibly by asking the right questions and by educating ourselves about calcium sources as well as the issues that confuse patients and clinicians alike.

Dr. Kitchin teaches the Tone Your Bones Osteoporosis Education Luncheonfor osteoporosis patients every Wednesday from 11:00 to 1:00 at the Kirklin Clinic at UAB. The class is open to the public. To register for the class, call 205.801.8187.