Should prophylaxis of vitamin D (Vit D) and calcium supplements be given to normal females?

Vitamin D and Calcium Supplementation in Normal Females

Routine prophylactic vitamin D and calcium supplementation should NOT be given to normal premenopausal women, and should NOT be given to postmenopausal women at doses of 400 IU or less of vitamin D with 1000 mg or less of calcium, as these low doses provide no fracture prevention benefit while increasing kidney stone risk. 1, 2

Premenopausal Women

Do not routinely supplement with vitamin D and calcium for fracture prevention in premenopausal women. The evidence is clear on this point:

• The USPSTF concludes there is inadequate evidence to determine any benefit of vitamin D and calcium supplementation for fracture prevention in premenopausal women 1, 2
• A 2023 Cochrane review of seven RCTs in premenopausal women found calcium and vitamin D supplementation (alone or combined) had no effect on bone mineral density at the total hip or lumbar spine 3
• The Cochrane review explicitly states: "Our results do not support the isolated or combined use of calcium and vitamin D supplementation in healthy premenopausal women as a public health intervention" 3

Exception: Check vitamin D levels in high-risk premenopausal women

• Female athletes with limited sun exposure may need 1000-2000 IU vitamin D3 daily, as 21.5-80% have abnormal vitamin D levels 4
• Check serum 25-hydroxyvitamin D levels rather than empirically supplementing 4

Postmenopausal Women

The recommendation differs based on dosage and individual risk factors:

Low-Dose Supplementation (≤400 IU vitamin D + ≤1000 mg calcium): DO NOT USE

• The USPSTF recommends against daily supplementation with 400 IU or less of vitamin D and 1000 mg or less of calcium in postmenopausal women (Grade D recommendation) 1, 2
• These low doses have no net benefit for fracture prevention with moderate certainty 1
• Harm documented: Increases kidney stone incidence (1 stone per 273 women over 7 years in the Women's Health Initiative) 1, 4

Higher-Dose Supplementation (>400 IU vitamin D + >1000 mg calcium): INSUFFICIENT EVIDENCE

• The USPSTF states there is inadequate evidence about benefits and harms of higher doses for fracture prevention 1, 2
• The balance of benefits and harms cannot be determined 1, 2

Appropriate Use in Postmenopausal Women

Focus on dietary intake rather than supplements:

• The Institute of Medicine recommends 1200 mg/day calcium for postmenopausal women, preferably from dietary sources 5, 4
• Dietary calcium reduces kidney stone risk, while calcium supplements increase it 5
• If supplements are necessary, take them with meals to bind dietary oxalate and reduce stone risk 5

Consider vitamin D supplementation (without calcium) in specific circumstances:

• Women over 50 may need 800-1000 IU vitamin D daily for bone health 4
• Vitamin D alone (800 IU) is recommended for fall prevention in adults ≥65 years with fall history or vitamin D deficiency 1
• Vitamin D alone appears as effective as combined calcium/vitamin D for restoring vitamin D levels 6

Alternative Approach: Screen for Osteoporosis Instead

The USPSTF recommends screening for osteoporosis rather than universal supplementation:

• Screen all women ≥65 years for osteoporosis 1
• Screen younger postmenopausal women whose fracture risk equals that of a 65-year-old white woman 1
• Treat diagnosed osteoporosis or vitamin D deficiency appropriately (these recommendations do not apply to those populations) 1, 2

Critical Caveats

This recommendation does NOT apply to:

• Women with diagnosed osteoporosis 1, 2
• Women with vitamin D deficiency 1, 2
• Women with history of osteoporotic fractures 2
• Institutionalized women (nursing home residents) 1

Common pitfall to avoid:

• Do not assume that because calcium and vitamin D are "natural" and inexpensive, they should be given universally 1. The evidence shows no benefit and documented harm in normal women at commonly used doses.