Calcium Citrate: Uses, How It Works, and Safety Information
Overview
Calcium citrate is a highly absorbable form of calcium supplement that can be taken with or without food. Unlike calcium carbonate, it doesn’t require stomach acid for absorption, making it an excellent choice for people taking acid-reducing medications or those with low stomach acid production.
Calcium is essential for building and maintaining strong bones, and also plays critical roles in muscle function, nerve transmission, blood clotting, and heart rhythm.
Brand Names
- Citracal
- Solgar Calcium Citrate
- Various store brands
- Often combined with vitamin D
How It Works
Calcium citrate is already in a soluble form that doesn’t require stomach acid to be absorbed. When you take calcium citrate:
- It dissolves readily in the digestive tract
- Calcium ions are released and absorbed in the small intestine
- Absorption occurs whether taken with or without food
- Can be taken at any time of day
Key characteristics:
- 21% elemental calcium (lower than calcium carbonate)
- Doesn’t require stomach acid for absorption
- Can be taken on empty stomach
- Generally well tolerated
Common Uses
Bone health:
- Osteoporosis prevention
- Osteoporosis treatment (as part of comprehensive therapy)
- Maintaining bone density
- Supporting bone health during aging
Preferred calcium form when:
- Taking proton pump inhibitors (PPIs)
- Taking H2 blockers (famotidine, etc.)
- Low stomach acid (achlorhydria)
- History of gastric bypass surgery
- Inflammatory bowel disease
- Elderly (stomach acid naturally decreases with age)
General calcium supplementation:
- Inadequate dietary calcium intake
- Increased needs (pregnancy, lactation)
- Lactose intolerance limiting dairy intake
- Vegan or vegetarian diets
Forms Available
Tablets:
- 200 mg to 315 mg elemental calcium per tablet
- Regular and petite sizes
- Often combined with vitamin D
Slow-release formulations:
- Citracal Slow Release
- May improve tolerance
Liquid and powder:
- For those who can’t swallow tablets
- Can be mixed with beverages
Elemental Calcium Content
Calcium citrate has lower elemental calcium percentage:
| Product Label | Elemental Calcium |
|---|---|
| Calcium citrate 950 mg | ~200 mg calcium |
| Calcium citrate 1,190 mg | ~250 mg calcium |
| Calcium citrate 1,500 mg | ~315 mg calcium |
Comparison to calcium carbonate:
- Calcium carbonate: 40% elemental calcium
- Calcium citrate: 21% elemental calcium
- Need more tablets of citrate for equivalent calcium
Important Considerations
Advantages:
- Better absorbed without food
- Good choice with acid-reducing medications
- Easier on the stomach
- Less constipating for some people
Disadvantages:
- More tablets needed (lower calcium per tablet)
- Usually more expensive
- Larger tablets
Who benefits most:
- People over 50 (declining stomach acid)
- Those on PPIs or H2 blockers
- Post-bariatric surgery patients
- Anyone with digestive issues
Vitamin D connection:
- Vitamin D enhances calcium absorption
- Many products include vitamin D
- Check if additional vitamin D needed
Comparison to Calcium Carbonate
| Feature | Calcium Citrate | Calcium Carbonate |
|---|---|---|
| Elemental calcium | 21% | 40% |
| Requires stomach acid | No | Yes |
| Take with food | Not required | Required |
| Tablets per day | More | Fewer |
| Cost | Higher | Lower |
| For PPI users | Preferred | May have reduced absorption |
Related Pages
Sources
- FDA-approved labeling for calcium citrate products
- National Osteoporosis Foundation guidelines
- National Institutes of Health Office of Dietary Supplements
- Manufacturer prescribing information