Vitamin D

What is Vitamin D?

Vitamin D is a fat-soluble hormone-like vitamin synthesised in skin exposed to UVB light and obtained from diet and supplements. Vitamin D deficiency is highly prevalent in India (60–80% of reproductive-age adults) and is associated with PCOS, impaired ovarian function, reduced IVF implantation rates, and male factor infertility. Target serum level before fertility treatment: 40–60 ng/mL (100–150 nmol/L). Supplementation: 1,000–4,000 IU/day depending on baseline level; tested by serum 25(OH)D assay.

Key facts about Vitamin D

• Deficiency defined as serum 25(OH)D <20 ng/mL; insufficiency: 20–29 ng/mL; optimal for fertility: 40–60 ng/mL
• India-specific: 60–80% of reproductive-age adults are vitamin D deficient or insufficient due to indoor lifestyle, skin pigmentation, and low dietary intake
• Female fertility: low vitamin D associated with PCOS (worse insulin resistance, higher androgen levels), reduced AMH response, poorer IVF implantation rates
• Male fertility: vitamin D receptors present on sperm — deficiency linked to lower sperm motility and testosterone levels
• Test: serum 25-hydroxyvitamin D [25(OH)D] — can be done any time of day, not cycle-dependent
• Standard supplementation: 1,000–2,000 IU/day (maintenance); 4,000 IU/day (correction of deficiency)
• Recheck level 3 months after starting supplementation — adjust dose to achieve target
• Fat-soluble — take with largest meal of the day for best absorption; D3 (cholecalciferol) preferred over D2

Why Vitamin D matters in fertility

Vitamin D is the most common and most correctable nutritional deficiency in Indian fertility patients. Unlike most supplements, testing is straightforward (serum 25(OH)D), correction is inexpensive, and there is mechanistic and associative evidence linking deficiency to multiple fertility outcomes. Every fertility workup should include a 25(OH)D level — correcting deficiency before IVF is low-cost, low-risk, and potentially meaningful.

What are related terms to Vitamin D?