Andrea Wong, PhD, executive vice president of scientific and regulatory affairs for The Council for Responsible Nutrition, spoke with NutraIngredients-USA about the report. Wong said that the results were preliminary in nature and, being highly surprising, needed more confirmation.
“CRN is surprised by the results of this new study as previous research has indicated calcium supplementation may have a protective effect against colorectal polyps. Even the study’s authors acknowledge they do not understand the mechanism by which the calcium supplements seemingly had the opposite effect of what was hypothesized. Given these opposing outcomes in the research to date, this is clearly a case where additional research is needed to discern whether this study’s outcome was an anomaly,” she said.
The study, which was published in the journal Gut, was led by Dr. Seth Crockett of the University of North Carolina School of Medicine in Chapel Hill. His team tracked outcomes for 2,000 people, aged 45 to 75, who all had a history of polyps.
The study participants were randomly assigned to take either daily calcium supplements, daily vitamin D supplements, both, or neither for three or five years.
Those who took calcium alone or a combination of calcium and vitamin D were more likely to have polyps six to 10 years after the start of the study, the findings showed.
Preliminary finding shouldn’t cancel out clear benefits
The danger with such studies, Wong said, is that the results can be inflated to mean a blanket condemnation of calcium supplementation is called for. The suggestion of an increased risk of cancer grabs far more attention than does a claim such as “helps maintain healthy bone mass.” Most consumers would gladly surrender the latter if it meant they could avoid the former. Indeed, the lead of an article about the study in the Chicago Tribune read: “Could the calcium supplement you take to help your bones be harming your colon?”
“Until further research is conducted, we caution the medical community and consumers against haphazardly dismissing or downplaying the value of calcium supplementation, particularly in people most likely to develop osteoporosis or bone loss,” Wong said.
“This particular study focused on a very specific population—patients with a history of colorectal polyps—and therefore, the study’s results are not applicable to the general population. We recommend consumers with a history of colorectal polyps talk with their doctors about whether calcium supplementation is appropriate,” she added.
More than a quarter of supplement users take calcium
CRN said data show that calcium is among the most popular of dietary supplements. According to the organization’s 2017 Consumer Survey on Supplements, 26% of regular supplement users take products featuring the mineral.
In addition, the organization noted:
- Calcium is essential at every life stage. A proper intake of calcium plus vitamin D helps build optimal bone mass during childhood and adolescence and helps maintain it during old age.
- Calcium is also implicated in other health protection mechanisms, including helping blood to clot, aiding in nerve signaling and in muscle contractions.
- Americans are falling short in calcium, which has been identified by national health authorities as a “nutrient of public health concern.”
 Baron JA, Barry EL, Mott LA, et al. A trial of calcium and vitamin D for the prevention of colorectal adenomas. N Engl J Med 2015;373:1519–30.
 Bonithon-Kopp C, Kronborg O, Giacosa A, et al. Calcium and fibre supplementation
in prevention of colorectal adenoma recurrence: a randomised intervention trial. European cancer prevention organisation study group. Lancet 2000;356:1300–6.
 Baron JA, Beach M, Mandel JS, et al. Calcium supplements for the prevention of colorectal adenomas. Calcium polyp prevention study group. N Engl J Med 1999;340:101–7.
 Pence BC. Role of calcium in colon cancer prevention: experimental and clinical studies. Mutat Res 1993;290:87–95.