Writing in the Journal Gut the team report on findings from the U.S. Vitamin D/Calcium Polyp Prevention Study which was a chemopreventive trial originally designed to see if calcium carbonate (or calcium carbonate plus vitamin D) supplements reduced the likelihood of further pre-malignant bowel growths in people who had previously had a polyp removed.
However, the team behind the study were surprised to find the opposite effect.
Indeed, the use of calcium supplements alone led to a 2.5 fold increase in risk of pre-cancerous polyps known as SSAs (sessile serrated adenomas). Meanwhile, combined calcium and vitamin D supplementation resulted in nearly quadruple the risk.
Calcium and all minerals actually, are inorganic. Consequently, they are not easily absorbed. It's required they be bound to some other substance (preferably organic) in order to be utilized at all. The inorganic salt, carbonate, neutralizes a required stomach acid. Among many key physiological requirements and ratios, stomach acid is desperately needed for absorption of ALL minerals.
Calcium and vitamin D supplements are taken by roughly 40% of the US population, which equates to over 100 million people. Women represent the majority of those taking calcium supplements in the general population. It is interesting therefore that polyps are at least as common if not more common in women than men, in contrast to conventional adenomas, which are more common in men.
With the support of medical research, the market has been flooded with calcium supplements, many which fail to take into consideration calcium metabolism. You have all heard the old saying, "You are what you eat." In light of today’s food supplies, it may be more apropos to say "You are what you absorb." A mineral that is not absorbed cannot get into the bones and critical body systems; it just floats in the blood stream and then forms deposits in the joints. The amount absorbed is more important than the quantity consumed.
Calcium carbonate may cause acid rebound: the stomach overcompensates for the high dose of calcium carbonate, which is alkaline, by churning out more acid. For that reason, people with a history of stomach ulcers are advised that they may not tolerate it and may have to switch to calcium citrate.
In this study, there was no increase in risk associated with vitamin D supplements in isolation; nor was there any link between dietary calcium and increased polyp risk, the researchers noted.
The increase in risk of developing serrated polyps appeared to be a long-term effect with a substantial period of latency. In the treatment (supplementation) phase, there was no effect of either calcium (either with or without vitamin D) on the incidence of SSAs. However, the increased risk of SSAs became evident during bowel examinations following the subsequent observational stage, 3-5 years after the end of supplementation.
"Using data from a recently completed randomised chemoprevention trial of vitamin D and calcium in patients with colorectal adenomas, we found that calcium and the combination of calcium and vitamin D increased the risk of SSA/Ps 6-10 years after supplementation began," commented lead author Seth D. Crockett, MD, from the University of North Carolina's Division of Gastroenterology and Hepatology.
The randomised controlled trial included 2259 individuals aged between 45-75 years from multiple centres in the U.S. All participants had previously undergone removal of an adenoma at baseline.
Patients were randomised to four main groups: 1200 milligrams / day (mg/d) of calcium carobate plus 1000 IU/d of vitamin D3, calcium carbonate plus placebo, vitamin D plus placebo or placebo. Patients underwent surveillance colonoscopies after 3 or 5 years of supplementation (treatment phase), and again a further 3-5 years later (observation phase).
Why Calcium Needs Magnesium
Magnesium plays a key role in regulating blood pressure naturally. According to Linda Bolton "80 percent of the population have an unhealthy balance of 10 calcium to 1 magnesium in our 70 trillion cells." Multiple research studies have suggested that calcium supplemented with magnesium improves cardiovascular health and bone mineral density. Magnesium deficiency alters calcium metabolism and the hormones that regulate calcium, resulting in imbalances that lead to disease.
Dietary surveys have suggested that sufficient magnesium intake with calcium in foods may reduce the chance of having a stroke. Imbalances between calcium and magnesium may increase the risk of abnormal heart rhythms, which increases the risk of complications after a heart attack.
Various types of polyps can grow within the lower large bowel. Hyperplastic polyps (HP- a type of serrated polyp) are more common, but less likely to turn cancerous than the more advanced SSA type, explained the researchers.
Most colon polyps are adenomas, and the vast majority--about 90%--are completely harmless. But because it's usually not possible to tell which adenomas will become cancerous, doctors generally remove them during a colonoscopy.
Previous observational studies have found an inverse association between dietary calcium intake and risk of HP and SSA, while secondary analysis within this trial found no association.
"Taken together, our results would suggest that only calcium supplementation, not dietary calcium intake, is associated with SPs overall and SSA/Ps specifically," observed the researchers.
Very little other data exists on the links between calcium supplementation and colorectal cancer arising from serrated polyps. The findings therefore justify further research to verify evidence from this trial, suggested the scientists.
"Further studies are recommended to confirm these results, which may have important implications for CRC screening and prevention," concluded Crockett.
Meanwhile, "Patients with a history of premalignant serrated polyps, especially women and smokers, may wish to avoid vitamin D and calcium supplementation," the researchers recommended.