Can long-term calcium supplementation (≥1 g elemental calcium daily) cause gastric inflammation and the development of gastric or colonic polyps?

Prolonged Calcium Supplementation and Gastric/Colonic Polyp Risk

Long-term calcium supplementation at doses ≥1 g daily does not cause gastric inflammation, but emerging evidence suggests it may increase the risk of sessile serrated adenomas/polyps (SSA/Ps) in the colon when used for extended periods (6-10 years), though it modestly reduces the risk of conventional adenomas. 1

Gastric Effects of Calcium Supplementation

Direct Gastric Inflammation

• Calcium supplements do not cause gastric inflammation or gastritis. 2, 3
• The primary gastric side effects are constipation, bloating, and dyspepsia—not inflammatory changes. 2
• Calcium carbonate may exacerbate gastroesophageal reflux symptoms due to its requirement for gastric acidity and potential for gastric distension, but this is not inflammatory gastritis. 3, 4

Gastric Polyps

• No evidence links calcium supplementation to gastric polyp formation. 2, 5
• The guidelines and research literature do not identify calcium supplements as a risk factor for fundic gland polyps or gastric hyperplastic polyps. 6

Colonic Polyp Effects: A Complex Picture

Conventional Adenomas (Tubular Adenomas)

• Calcium supplementation at 1200-2000 mg/day modestly reduces the risk of recurrent colorectal adenomas (OR 0.74,95% CI 0.58-0.95). 7
• The protective effect appears most pronounced for advanced adenomas (RR 0.65,95% CI 0.46-0.93). 8
• This benefit was demonstrated in patients with previous adenomas during 3-4 years of supplementation. 7, 8

Serrated Polyps: A Critical Concern

• A major 2019 randomized trial found that calcium supplementation (1200 mg/day) significantly increased the risk of sessile serrated adenomas/polyps (SSA/Ps) during the late observational phase (6-10 years after supplementation began). 1
• The adjusted risk ratio for SSA/Ps with calcium alone was 2.65 (95% CI 1.43-4.91), and for calcium plus vitamin D was 3.81 (95% CI 1.25-11.64). 1
• This is a late effect—no increased risk was observed during the initial 3-5 year treatment phase, only after treatment ceased. 1
• SSA/Ps are important colorectal cancer precursors through the serrated pathway, making this finding clinically significant. 1

Clinical Algorithm for Decision-Making

When Calcium Supplementation is Indicated

1. Prioritize dietary calcium sources first (target 1000-1200 mg/day from food). 2
2. Only supplement when dietary intake is inadequate (<800 mg/day from diet). 2
3. Never exceed 2000 mg/day total calcium (diet + supplements) in adults >50 years. 2

Choosing the Right Formulation to Minimize GI Effects

• For patients with normal gastric acid production: Calcium carbonate (40% elemental calcium) taken with meals is cost-effective but causes more constipation and bloating. 2, 3, 4
• For patients with GERD, on PPIs, or elderly with achlorhydria: Calcium citrate (21% elemental calcium) is preferred—can be taken without food and causes fewer GI symptoms. 3, 9, 5
• Divide doses: Never take >500-600 mg elemental calcium at one time to optimize absorption and minimize side effects. 3, 9

Monitoring for Polyp Risk

• Patients on long-term calcium supplementation (>5 years) should be counseled about the potential late increased risk of serrated polyps. 1
• Consider discontinuing calcium supplements after 5 years if dietary calcium intake can be optimized, particularly in patients with adequate bone density or those at higher baseline risk for colorectal neoplasia. 1
• Maintain appropriate colorectal cancer screening intervals—do not extend intervals based on any perceived protective effect from calcium. 1

Critical Caveats

The Serrated Polyp Paradox

• The finding that calcium reduces conventional adenomas but may increase serrated polyps represents a fundamental shift in our understanding of calcium's effects on colorectal carcinogenesis. 1
• This late effect (appearing 6-10 years after starting supplementation) means patients may develop increased SSA/P risk even after stopping calcium. 1
• The mechanism is unknown but may relate to altered colonic microbiome or metabolic changes that persist after supplementation ends. 1

Special Populations Requiring Calcium

• Patients on corticosteroids: Require 800-1000 mg/day calcium plus vitamin D to prevent bone loss—the bone protection benefit outweighs polyp concerns in this high-risk group. 2
• Patients with calcium oxalate stones: Should obtain calcium from dietary sources timed with meals rather than supplements, as supplemental calcium increases nephrolithiasis risk (RR 1.17). 2
• Patients with inflammatory bowel disease or short bowel syndrome: May require calcium supplements with meals to bind oxalate and prevent calcium oxalate stones, despite malabsorption. 2

Cardiovascular and Renal Concerns

• Calcium supplements (but not dietary calcium) modestly increase cardiovascular risk in some studies, though evidence remains inconsistent. 2
• Supplemental calcium increases kidney stone risk, while dietary calcium is protective. 2

Bottom Line for Clinical Practice

Do not prescribe calcium supplements routinely for "bone health" in community-dwelling adults without documented inadequate dietary intake. 2 When supplementation is necessary, use the lowest effective dose for the shortest duration needed, prioritize calcium citrate in patients with GI issues 3, 9, and counsel patients about the emerging evidence of late serrated polyp risk with prolonged use beyond 5 years. 1 Calcium does not cause gastric inflammation or gastric polyps. 2, 5