What calcium supplement should I take since my bariatric vitamin (multivitamin for bariatric patients) doesn't contain calcium?

Calcium Supplementation After Bariatric Surgery

You should take 1200-1500 mg of elemental calcium daily (split into divided doses) using calcium citrate as your preferred supplement, taken with or without food, ensuring doses are separated by several hours and taken 1-2 hours apart from iron supplements. 1

Type of Calcium Supplement

Calcium citrate is the preferred form for bariatric patients because it is more bioavailable and does not require stomach acid for absorption—a critical consideration given the altered gastric environment after bariatric surgery. 1 While calcium carbonate may be better tolerated by some patients, calcium citrate offers superior absorption in the post-surgical setting and is particularly important if you're at risk for kidney stones. 1

The British Obesity and Metabolic Surgery Society guidelines acknowledge that no large randomized controlled trials have directly compared these two forms across all bariatric procedures, but the physiological rationale strongly favors citrate. 1

Dosing Strategy

Total Daily Amount by Surgery Type:

• Gastric band (AGB), Sleeve gastrectomy (SG), or Roux-en-Y gastric bypass (RYGB): 1200-1500 mg elemental calcium daily from food and supplements combined 1
• Biliopancreatic diversion/duodenal switch (BPD/DS): 1800-2400 mg elemental calcium daily 1

How to Take It:

• Divide doses throughout the day—no single dose should exceed 500-600 mg of elemental calcium to optimize absorption and minimize gastrointestinal side effects 2, 3, 4
• Calcium citrate: Take with or without meals 1, 3
• Calcium carbonate (if used): Must be taken with meals for optimal absorption 1, 3

Critical Timing Considerations

Separate calcium from iron by 1-2 hours because calcium inhibits iron absorption—this is particularly important since you likely need iron supplementation as well after bariatric surgery. 1, 3

Understanding Elemental Calcium Content

This is where many patients get confused:

• Calcium citrate tablets contain only 21% elemental calcium, so a 950-1000 mg tablet provides approximately 200-210 mg of elemental calcium 2, 3
• Calcium carbonate tablets contain 40% elemental calcium, so a 500 mg tablet provides 200 mg of elemental calcium 3, 5

You must read labels carefully to determine how much elemental calcium you're actually getting, not just the total tablet weight. 2, 3

Practical Regimen Example

For a typical 1200 mg elemental calcium daily requirement:

• Take one 950-1000 mg calcium citrate tablet (≈200 mg elemental calcium) twice daily, separated by several hours 2, 3
• Or take 600 mg elemental calcium (three 1000 mg calcium citrate tablets) divided into morning and evening doses 2, 3
• Ensure you're also getting calcium from dietary sources and count this toward your total 1

Vitamin D Co-Supplementation

You must take vitamin D alongside calcium because calcium absorption depends on adequate vitamin D levels. 1 After bariatric surgery, you need 2000-4000 IU of vitamin D3 daily (higher for BPD/DS), with adjustments based on blood levels to maintain serum 25-hydroxyvitamin D above 75 nmol/L. 1

Monitoring and Adjustment

If your parathyroid hormone (PTH) is elevated despite adequate vitamin D levels and normal serum calcium, consider switching to a combined vitamin D and calcium supplement. 1 Your healthcare team should monitor your calcium status through alkaline phosphatase, vitamin D, PTH, and urinary calcium levels. 1

Important Safety Considerations

• Do not exceed 2000-2500 mg total daily calcium (from all sources combined) as excessive intake increases risk of kidney stones and potentially cardiovascular events 2, 3, 6
• Maintain good hydration to reduce kidney stone risk 1
• Prioritize dietary calcium sources when possible, as food-based calcium is more bioavailable and may protect against kidney stones 1
• Weight-bearing activity should be encouraged alongside supplementation for bone health 1

Common Pitfalls to Avoid

• Taking calcium and iron together (separate by 1-2 hours) 1
• Taking doses larger than 500-600 mg elemental calcium at once (reduces absorption) 2, 3, 4
• Confusing total tablet weight with elemental calcium content 2, 3
• Forgetting that calcium carbonate requires food for absorption while citrate does not 1, 3
• Neglecting vitamin D supplementation, which is essential for calcium absorption 1