Calcium Intake and Supplementation Recommendations
The recommended dietary calcium intake for adults is 1000 mg/day for those aged 19-50 years and men aged 51-70 years, and 1200 mg/day for women over 50 years and men over 70 years, with calcium preferably obtained from food sources rather than supplements whenever possible. 1, 2, 3
Age-Specific Calcium Requirements
- Adults aged 19-50 years and men aged 51-70 years should consume 1000 mg of calcium daily 1, 2
- Women over 50 years and men over 70 years should consume 1200 mg of calcium daily 1, 2
- Pregnant and lactating women should follow the recommendations for their age group (1000 mg/day) 3
- The upper limit for calcium intake is 2500 mg/day for people under 50 years and 2000 mg/day for those over 50 years to avoid potential adverse effects 1, 3
Dietary Sources vs. Supplements
- Calcium-rich foods and beverages, particularly dairy products, are the preferred sources of calcium due to their wide availability and minimal adverse effects 1
- More than 70% of dietary calcium comes from dairy products in typical Western diets 1
- Non-dairy sources of calcium include leafy green vegetables and calcium-fortified foods 1
- For those who cannot meet calcium requirements through diet alone, supplements should be considered 1, 3
- When estimating dietary calcium intake, clinicians can assume most adults consume about 300 mg of calcium daily from non-dairy sources and then calculate additional intake from dairy products 1
Calcium Supplement Considerations
- Calcium carbonate (40% elemental calcium) is the most common and cost-effective supplement but should be taken with meals to optimize absorption 1, 3
- Calcium citrate (21% elemental calcium) can be taken without food and is preferred for individuals with reduced stomach acid or those taking medications that reduce stomach acid 1, 3
- The maximum dose of elemental calcium that should be taken at one time is 500 mg to optimize absorption 1
- Dividing doses greater than 500 mg throughout the day improves absorption 3
Potential Risks and Benefits
- Calcium supplements may modestly reduce the formation of colorectal adenomas 1
- However, high calcium intake primarily through supplements has been associated with increased risk for prostate cancer, especially more aggressive forms 1
- Calcium supplements can cause gastrointestinal side effects such as constipation and bloating 1, 3
- Supplement use, but not increased dietary intake, modestly increases the risk of kidney stones 1
- Evidence regarding cardiovascular risks with calcium supplementation is inconsistent and inconclusive 1
- The National Osteoporosis Foundation and American Society for Preventive Cardiology state that calcium intake from food and supplements that does not exceed the upper limit (2000-2500 mg/day) should be considered safe from a cardiovascular standpoint 1
Practical Recommendations
- Assess current calcium intake before recommending supplements 1
- For individuals with suboptimal calcium intake, first encourage increasing dietary sources 1
- If dietary intake remains insufficient, supplement with the minimum amount needed to reach recommended levels 1
- Those taking calcium supplements should be advised to take calcium carbonate with meals to optimize absorption 1
- Avoid taking calcium supplements with foods or medications that may interfere with absorption 3
- Adequate vitamin D is essential for optimal calcium absorption 1
Special Considerations
- Individuals with a history of kidney stones should prioritize dietary calcium sources over supplements 1
- Those at risk for prostate cancer should be cautious about high-dose calcium supplementation 1
- Patients with achlorhydria or those taking histamine-2 blockers or proton pump inhibitors should choose calcium citrate over calcium carbonate 3