Can a regular multivitamin (MV) cause increased urination in women over 50?

Can a Regular Multivitamin Cause Increased Urination in Women Over 50?

A regular multivitamin for women over 50 is unlikely to directly cause increased urination, but specific components—particularly high-dose vitamin C (≥500 mg) and calcium supplements—have been associated with urinary storage symptoms and increased urinary frequency in women. 1

Specific Vitamin Components That May Affect Urination

Vitamin C and Urinary Symptoms

• High-dose vitamin C from diet and supplements (≥500 mg/day versus <50 mg/day) was associated with a 3.42-fold increased likelihood of storage symptoms, especially combined frequency and urgency in women. 1
• Women consuming high-dose vitamin C were more likely to report urinary storage problems, which include increased frequency of urination. 1
• Most standard multivitamins for women over 50 contain 60-90 mg of vitamin C, which is below the threshold associated with urinary symptoms, but some formulations may contain higher doses. 1

Calcium and Urinary Frequency

• Both dietary and supplemental calcium were positively associated with urinary storage symptoms in women, with calcium supplements ≥1000 mg/day showing a 2.04-fold increased risk of storage symptoms compared to no supplementation. 1
• Many multivitamins for women over 50 contain 200-500 mg of calcium, which is below the high-risk threshold but may still contribute to symptoms in susceptible individuals. 1
• The mechanism may involve increased urinary calcium excretion, which can affect bladder function. 2

Vitamin B12 and Urine Volume

• Urinary excretion of vitamin B12 is strongly correlated with urine volume (r=0.683 in young women, r=0.523 in elderly), meaning higher B12 intake may lead to increased urine production as the body excretes excess amounts. 3
• However, even a 500-fold increase in B12 intake only increased urinary B12 by 1.3-fold, suggesting this effect is modest. 3

Clinical Assessment Approach

Determine If the Multivitamin Is the Culprit

• Review the specific multivitamin formulation to identify vitamin C content (problematic if ≥500 mg), calcium content (problematic if ≥1000 mg), and other components. 1
• Consider a trial discontinuation of the multivitamin for 2-4 weeks to assess whether urinary frequency improves. 1
• If symptoms resolve, consider switching to a lower-dose formulation or obtaining nutrients from dietary sources instead. 1

Alternative Explanations to Rule Out

• Vitamin D deficiency itself can cause urge urinary incontinence and increased frequency in postmenopausal women, so paradoxically, inadequate vitamin D may be contributing to symptoms rather than the multivitamin. 4
• Diuretic medications (commonly used in women over 50 for hypertension) can increase urination and may interact with B-vitamin status. 5
• Other medical conditions common in this age group (overactive bladder, diabetes, urinary tract infections) should be considered. 1, 4

Practical Recommendations

If Continuing Multivitamin Use

• Choose a formulation with vitamin C <500 mg and calcium <1000 mg to minimize risk of urinary storage symptoms. 1
• Take the multivitamin with meals rather than between meals to optimize absorption and minimize potential bladder irritation. 6
• Ensure adequate hydration (at least 2 liters of fluid daily) to prevent concentrated urine, which can irritate the bladder. 2

If Symptoms Persist

• Consider obtaining vitamin D levels, as deficiency may contribute to urge incontinence; supplementation with vitamin D3 50,000 IU weekly for 8 weeks has been shown to reduce urinary frequency and nocturia in postmenopausal women with vitamin D deficiency. 4
• Evaluate for other causes of increased urination including diabetes, urinary tract infection, or medication side effects. 5, 1

Important Caveats

• The association between micronutrients and urinary symptoms appears to be dose-dependent and symptom-specific, meaning not all women will experience these effects. 1
• Standard multivitamins typically contain lower doses of vitamin C and calcium than the thresholds associated with urinary symptoms, making them less likely to be problematic. 1, 7
• Individual susceptibility varies considerably, and some women may be more sensitive to these effects than others. 1