What is this ingredient? Vitamin D3 (cholecalciferol) is a fat‑soluble vitamin and prohormone that the body can synthesize in the skin from sunlight or obtain from food and supplements. After hepatic and renal activation to 1,25‑dihydroxyvitamin D, it binds the vitamin D receptor (VDR) to regulate genes involved in calcium and phosphate balance, immune modulation, and cell growth and differentiation. Low 25‑hydroxyvitamin D levels are common in people with obesity, insulin resistance, and polycystic ovary syndrome (PCOS) and have been associated with adverse metabolic profiles in observational work.
Randomized controlled trials in vitamin‑D–deficient women with PCOS show that cholecalciferol supplementation can modestly improve some metabolic markers. In one 8‑week RCT using 50,000 IU/week in vitamin‑D–deficient PCOS women, vitamin D significantly reduced fasting plasma glucose and increased adiponectin and β‑cell function versus placebo [2]. Another 12‑week RCT in PCOS women with deficiency or insufficiency (2,000 IU/day) reported reductions in BMI, waist‑to‑hip ratio, insulin levels, HOMA‑IR, and triglycerides and LDL‑cholesterol compared with controls [3]. However, not all trials find broad metabolic benefits; some show improved 25(OH)D with only selective changes in glucose dynamics [0,9].
Why include it in this formula? The “Inositol - 120” product combines myo‑inositol, D‑chiro‑inositol, omega‑3 powder, magnesium glycinate, zinc, and vitamin D3. This profile clearly targets insulin sensitivity, cardiometabolic health, and frequently, cycle or PCOS‑related concerns. Within this architecture, vitamin D3 is the "endocrine and metabolic" pillar. It supports insulin sensitivity and body‑composition changes in obese or insulin‑resistant individuals when combined with lifestyle measures, as seen in a double‑blind RCT where cholecalciferol plus weight‑loss significantly improved clamp‑measured insulin sensitivity versus placebo [8].
In PCOS‑focused trials, higher‑dose vitamin D (e.g., 4,000 IU/day) has also improved androgen indices (total testosterone, free androgen index), hs‑CRP, and hirsutism scores compared with lower doses or placebo, suggesting benefits for both metabolic and hyperandrogenic features in this population [4]. In this formula, vitamin D3 works alongside inositols (insulin second messengers), magnesium and zinc (insulin and reproductive cofactors), and omega‑3s (inflammatory tone and lipids) to create a more favorable hormonal and metabolic environment. Rather than acting alone, cholecalciferol helps ensure that the improved signaling driven by inositols occurs in a vitamin‑D‑replete, endocrine‑balanced system, consistent with modern PCOS and insulin‑resistance management strategies.
References
- [0] Effects of vitamin D supplementation on metabolic and endocrine parameters in PCOS: a randomized-controlled trial
- [2] The effect of vitamin D supplementation on insulin resistance, visceral fat and adiponectin in vitamin D deficient women with polycystic ovary syndrome: a randomized placebo-controlled trial
- [3] Effects of vitamin D supplementation on metabolic parameters in women with polycystic ovary syndrome: a randomized controlled trial
- [4] Effect of Two Different Doses of Vitamin D Supplementation on Metabolic Profiles of Insulin-Resistant Patients with Polycystic Ovary Syndrome
- [8] Effect of Vitamin D Supplementation on Obesity-Induced Insulin Resistance: A Double-Blind, Randomized, Placebo-Controlled Trial