Calcium Supplementation for Premenstrual Syndrome
For mild-to-moderate premenstrual syndrome in otherwise healthy reproductive-age women, recommend 1200 mg of elemental calcium daily (preferably as calcium carbonate), which should be considered first-line therapy. 1, 2
Evidence-Based Dosing for PMS
The specific dose of 1200 mg of elemental calcium per day has been rigorously tested in randomized controlled trials and demonstrates significant efficacy for PMS symptoms. 1, 3
- A large multicenter, double-blind, placebo-controlled trial (n=466) demonstrated that 1200 mg daily of elemental calcium as calcium carbonate resulted in a 48% reduction in total symptom scores by the third treatment cycle, compared to only 30% reduction with placebo. 1
- This dose significantly reduced symptoms during both the luteal phase (p<0.001) and menstrual phase, with improvements across all four symptom factors: negative affect, water retention, food cravings, and pain. 1
- An earlier crossover trial using 1000 mg daily also showed benefit (p=0.011 for luteal phase symptoms), but the 1200 mg dose has stronger evidence and is the recommended standard. 3
Formulation and Administration
Calcium carbonate is the preferred formulation for PMS treatment based on the clinical trial evidence. 1, 2
- Calcium carbonate provides 40% elemental calcium content, making it cost-effective and widely available. 4
- Take with meals to optimize absorption, as gastric acidity is required. 4
- Divide the dose into two 600 mg doses (morning and evening) rather than a single daily dose to improve absorption and minimize gastrointestinal side effects like constipation and bloating. 4
Clinical Algorithm for PMS Management
Step 1: Confirm PMS diagnosis
- Symptoms must occur cyclically during the luteal phase and be at least 50% greater than intermenstrual phase symptoms. 3
- Prospective daily symptom tracking over 2 cycles is essential before initiating treatment. 1
Step 2: Initiate calcium supplementation
- Start 1200 mg elemental calcium daily (as calcium carbonate, divided into two 600 mg doses with meals). 1, 2
- Continue for at least 3 menstrual cycles, as maximal benefit typically appears by the third cycle. 1
Step 3: Consider vitamin D co-administration
- While the PMS trials used calcium alone, emerging evidence suggests vitamin D deficiency may contribute to PMS pathophysiology. 5, 6
- Women with high vitamin D intake (median 706 IU/day) had a 41% lower risk of developing PMS compared to low intake. 6
- Consider adding 800 IU of vitamin D daily, particularly if dietary intake is inadequate. 5
Step 4: Escalate if inadequate response
- If symptoms persist after 3 cycles of calcium supplementation, selective serotonin reuptake inhibitors (SSRIs) should be considered as next-line therapy, especially for severe affective symptoms. 2
Important Safety Considerations
Upper safety limit: The 1200 mg dose for PMS is well below the 2000-2500 mg/day upper limit for reproductive-age women, making it safe for long-term use. 4
Common pitfalls to avoid:
- Do not use progesterone for PMS—it is ineffective despite widespread historical use. 2
- Avoid exceeding 1200 mg daily for PMS, as higher doses do not provide additional benefit and increase risk of constipation and potential kidney stones. 4, 1
- Calcium citrate may be substituted if gastrointestinal side effects are problematic, though the evidence base specifically used calcium carbonate. 4
Strength of Recommendation
This recommendation is based on Level I evidence from multiple randomized, double-blind, placebo-controlled trials showing consistent benefit. 1, 3, 2
- Calcium carbonate 1200 mg/day is designated as first-line therapy for mild-to-moderate PMS based on good scientific evidence. 2
- The number needed to treat is favorable: 73% of women reported symptom improvement on calcium versus 15% preferring placebo. 3
- This represents a simple, accessible, low-cost intervention with minimal side effects and established efficacy for improving quality of life in women with PMS. 5, 2