Denmark: High-dose Vitamin D Supplementation Study

High-dose vitamin D supplementation improves fasting insulin levels and high-density lipoprotein (HDL)-cholesterol in infertile men, says a recent study in the Journal of Clinical Endocrinology & Metabolism.

Many studies have suggested a link between vitamin D and glucose and lipid metabolism. Men with impaired gonadal function are known to have a higher risk of metabolic syndrome and mortality, and vitamin D may be a reversible modulator. Considering this, Martin Blomberg Jensen, Department of Growth and Reproduction, Rigshospitalet, Copenhagen, Denmark, and colleagues aimed to determine the effect of daily vitamin D and calcium supplementation for 150 days on glucose and lipid homeostasis in infertile men in a single-center, double-blinded, randomized clinical trial.

A total of 307 infertile men were included. They were randomly assigned in the ratio of 1:1 to a single dose 300,000 IU cholecalciferol followed by 1400 IU cholecalciferol + 500 mg of calcium daily (n = 151) or placebo (n = 156) for 150 days. Reported metabolic parameters including glycated hemoglobin A1c, fasting plasma glucose, homeostatic model assessment of insulin resistance (HOMA-IR), fasting serum insulin, triglycerides, and fasting plasma cholesterol were secondary endpoints. The primary endpoint semen quality has previously been reported.

Study Findings

• Men receiving vitamin D supplementation improved their vitamin D status, whereas vitamin D status was aggravated in the placebo group characterized by higher serum parathyroid hormone.
• At the end of the trial, men receiving vitamin D supplementation had 13% lower fasting serum insulin concentrations compared with the placebo-treated group (65 vs 74 pmol/L) and 19% lower HOMA-IR (2.2 vs 2.7).
• Moreover, men in the vitamin D group had higher high-density lipoprotein (HDL) cholesterol levels (1.38 vs 1.32 mmol/L) compared with the placebo group.

The researchers conclude, "vitamin D and calcium supplementation prevent a decline in insulin sensitivity and improve HDL cholesterol in infertile men at increased risk of developing metabolic syndrome and type 2 diabetes."

Reference

Rune Holt, Jørgen Holm Petersen, Elsa Dinsdale, Filip Krag Knop, Anders Juul, Niels Jørgensen, Martin Blomberg Jensen, Vitamin D Supplementation Improves Fasting Insulin Levels and HDL Cholesterol in Infertile Men, The Journal of Clinical Endocrinology & Metabolism, Volume 107, Issue 1, January 2022, Pages 98–108, https://doi.org/10.1210/clinem/dgab667

Keywords

Journal of Clinical Endocrinology & Metabolism, vitamin D supplementation, infertile men, HDL cholesterol, fasting insulin, type 2 diabetes, infertility, metabolic syndrome, glucose homeostasis, Martin Blomberg Jensen, calcium supplementation