Researchers at the Indian Council of Medical Research-National Institute of Nutrition in Hyderabad have found that Vitamin D3 is significantly more effective than Vitamin D2 in maintaining and restoring skeletal muscle and heart function. The study, published on September 1, 2026, in Molecular Nutrition and Food Research, was conducted using weaning male Sprague-Dawley rats.
Comparative Physiological Findings
Investigators observed that Vitamin D3 led to greater improvements in muscle mass, muscle fiber size, and grip strength compared to Vitamin D2. Furthermore, Vitamin D3 administration produced superior markers related to muscle development, energy metabolism, and cardiac contractility during recovery from deficiency. Blood analysis revealed that Vitamin D3 increased blood levels of 25OHD, the established biomarker for Vitamin D status, two-fold compared to Vitamin D2 when administered at the exact same dose.
Dr. Ayesha Ismail, Scientist F at the Indian Council of Medical Research-National Institute of Nutrition and corresponding author of the study, stated that Vitamin D3 increased blood levels of 25OHD two-fold compared to D2 administered at the same dose, noting that Vitamin D3 is more efficacious than D2 in certain muscle and heart related parameters.
Differential Efficacy Across Biomarkers
Despite the superior performance of Vitamin D3 in muscle and cardiac metrics, the study identified shared physiological pathways. Dr. Ismail noted that although both forms of vitamin D were effective in improving calcium-related parameters, vitamin D2 was less effective than vitamin D3 in several parameters related to muscle and heart structure and energy metabolism.
Dr. Bharati Kulkarni, Director of the Indian Council of Medical Research-National Institute of Nutrition, emphasized the broader research implications, stating that the findings indicate vitamin D3 may be more effective than vitamin D2 in maintaining and restoring skeletal muscle and cardiac functions. Dr. Kulkarni stressed that further studies are needed to establish the effects of the two forms of vitamin D on skeletal and extra-skeletal functions and their implications for supplementation and fortification programmes.
Public Health Context and Deficiency Prevalence
Vitamin D deficiency is a major global health challenge, affecting over 1 billion people worldwide, with an estimated 50 to 80 percent of populations experiencing insufficiency or deficiency. In India, nearly 80 percent of the population is reported to have inadequate vitamin D levels.
While both Vitamin D2 and D3 are widely utilized in dietary supplements and food fortification, empirical evidence comparing their extra-skeletal impacts on muscle and heart health has historically been limited. The findings from the Indian Council of Medical Research-National Institute of Nutrition provide controlled comparative data on their relative efficacy.
Because the research was conducted on male rats, further human clinical trials remain essential to establish whether these physiological effects translate directly to human populations before public health agencies revise nationwide supplementation guidelines.
