Women undergoing treatment for breast cancer are widely prescribed calcium and vitamin D supplements to prevent and manage osteoporosis, an unwanted side effect of breast cancer therapies.
Study author Gary G. Schwartz, Ph.D., a cancer epidemiologist at Wake Forest Baptist, said the purpose of the study was to examine whether a seemingly common sense prescribing practice actually works. “We evaluated clinical trial evidence for calcium and vitamin D supplementation in maintaining skeletal health of women with breast cancer,” he said. “At the doses recommended, the data show that these supplements are inadequate to prevent loss of BMD.”
Schwartz and co-author Mridul Datta, Ph.D., a postdoctoral fellow at Wake Forest Baptist, reviewed data from clinical trials that evaluated the effect of antiresorptive drugs on BMD and used the “before-after” data from the comparison group to assess change in BMD in pre- and in post-menopausal women. Overall, the results from 16 trials indicate that 500-1500 mg calcium and 200-1000 IU vitamin D, the doses commonly recommended, do not prevent loss of BMD in women with breast cancer. Despite supplementation, women lost BMD in virtually every clinical trial reviewed.
The study appears online ahead of print this month in the journal Critical Reviews in Oncology/Hematology.
Women with breast cancer lose BMD at a higher rate than their healthier counterparts, increasing their risk of fractures which are associated with significant declines in function and health-related quality of life, and in higher mortality rates.
Consequently, it is a common practice to prescribe calcium and vitamin D supplements to these women, a “low intensity” intervention that seems to make sense, Datta said, although it’s never really been tested. In the clinical trials reviewed, BMD in the women was measured at the beginning and end of the studies, Datta said, so if the supplementation worked to prevent BMD loss, “you should be able to see that in the data, and we clearly didn’t.”
Datta said it is possible that the BMD deficits could be worse in the absence of the supplements, but the results are concerning overall because cardiovascular disease is the main cause of mortality in women with breast cancer. There is growing evidence that calcium supplements may increase the risk of heart attack and stroke.
“The take-home message is that this very common practice of supplementation doesn’t really seem to be working,” Schwartz said. “Future trials are needed to evaluate the safety and efficacy of calcium and vitamin D supplementation in women undergoing breast cancer therapy.”
6 Ways To Ensure Calcium Is Not Leeching From Your Body
1. Food selections/combinations are critical
Try not to eat whole grains and calcium-rich foods at the same time. Whole grains contain a substance that binds with calcium and prevents proper absorption. Some foods that contain compounds such as oxalic or phytic acids, such as sweet potatoes, beans, rhubarb, celery and beets, can also decrease the amount of calcium that's absorbed when eaten at the same time as calcium-rich foods.
2. Avoid the causes of mineral excretion
Pass on phosphate-containing foods such as soft drinks. Phosphorus causes the body to excrete calcium. Limit or avoid high-protein animal foods. A diet high in protein causes calcium to be excreted from your body. Decrease caffeine consumption. People who smoke have significantly lower bone density, while drinking alcohol can also prevent your bones from absorbing the maximum nutrients from your food.
3. Get more Sunlight and Vitamin D
Vitamin D helps the body absorb calcium. Although some is found in oily fish, our main source comes from the effect of sunlight on your skin. It's estimated that half of us have a deficiency because we don't get outside enough or because we always use sunblock. It is especially important to maximize sun exposure between May and September to keep vitamin D levels topped up. Just 10 minutes of sunlight a day on bare arms and your face can cut your risk of bone fractures by a third. A half hour exposing your torso is equivalent to roughly 10,000 units of Vitamin D.
4. The right exercise
Another vital way to boost your bones is weight-bearing exercise --basically anything that has you upright and using your body weight. Good choices include squatting, rope skipping, aerobics, plyometrics, dancing or brisk walking. "Research shows that if you don't exercise you end up weeing out all the calcium you take in instead of storing it in your bones," warns Professor Dawn Skelton, an aging and health specialist at Glasgow Caledonian University. "Ideally we should aim for 150 minutes of moderate activity per week. "Put simply, the more hours we spend on our feet, the fewer bone breakages we should have in later life."
5. Avoid Medications and Medical Therapies
Acid-blocking medications used for heartburn and other gastrointestinal conditions can block the absorption of calcium through the stomach walls. Stomach acids break down food during the digestive process, allowing the nutrients to become absorbed into your body. Medications designed to stop acid production or decrease the amount of acids present in your stomach can have a negative effect on calcium.
6. Eat the right calcium in foods
Most supplements offer very low grade calcium which is barely absorbed.The best food sources are non-pasteurized raw dairy sources such as raw milk/yogurt, as well as bony fish, such as sardines. Leafy green veg such as kale, broccoli and spinach are also rich in calcium. Dried herbs and dried fruits such as figs and currants are also good choices. Seeds such as sesame, chia and flax are also rich sources of calcium. Also, enjoy foods that contain sulfur such as garlic and onions.
Marco Torres is a research specialist, writer and consumer advocate for healthy lifestyles. He holds degrees in Public Health and Environmental Science and is a professional speaker on topics such as disease prevention, environmental toxins and health policy.