Vitamin D3 is more effective than vitamin D2 at maintaining and restoring skeletal muscle and heart function, according to a new study from researchers at the ICMR-National Institute of Nutrition (ICMR-NIN) in Hyderabad. Published in the scientific journal Molecular Nutrition & Food Research, the animal study investigated how both nutrient forms impact physical strength, cardiac performance, and muscle structure beyond traditional bone health parameters.
How ICMR-NIN Researchers Tested Vitamin D2 vs. Vitamin D3
To compare the two nutrients commonly used in supplements and food fortification programs, researchers conducted experiments on weaning male Sprague-Dawley rats, according to ICMR-NIN findings published in September 2026. The laboratory animals were divided into four distinct diet groups: a vitamin D2 diet, a vitamin D3 diet, a combination of both forms, or a vitamin D-deficient diet.
The research team tracked multiple biological markers across the subjects. They evaluated body composition, muscle strength, muscle fiber size, cellular energy metabolism, and indicators linked to cardiac contractility. While both nutrient forms successfully regulated basic calcium levels, the physiological outcomes diverged sharply when evaluating structural and metabolic endpoints.
Did you know?
Most previous nutritional research focused strictly on how vitamin D supports skeletal health and calcium absorption, leaving muscle and cardiac tissue comparisons largely unexplored until now.
Muscle Mass and Grip Strength Differences
Rats receiving vitamin D3 displayed greater improvements in muscle mass, broader muscle fiber size, and higher physical grip strength compared to subjects given vitamin D2, according to the ICMR-NIN study. Furthermore, vitamin D3 proved more effective at enhancing biological markers associated with muscle growth and cellular energy metabolism.
“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,” explained Dr. Ayesha Ismail, a lead scientist and corresponding author of the study from ICMR-NIN.
Cardiac Function and Deficiency Recovery
The comparative analysis revealed similar advantages for cardiovascular health. Vitamin D3 produced stronger effects on indicators of cardiac contractility and metabolism, particularly among subjects recovering from an established vitamin D deficiency.
Dr. Bharati Kulkarni, Director of ICMR-NIN, noted that these experimental outcomes point toward potential shifts in public health strategy. “The findings indicate that vitamin D3 may be more effective than vitamin D2 in maintaining and restoring skeletal muscle and cardiac functions,” Dr. Kulkarni stated via press release.
Pro Tip
Public health officials and researchers caution that while these animal study results highlight clear biochemical differences, further clinical studies are required before altering widespread food fortification and supplement guidelines.
Frequently Asked Questions
What is the main difference between Vitamin D2 and Vitamin D3 found in the study?
While both forms maintain calcium levels, ICMR-NIN researchers found that vitamin D3 is significantly more effective at improving muscle mass, grip strength, cellular energy metabolism, and heart function, especially during recovery from a deficiency.
Where was the study conducted?
The study was conducted by researchers at the ICMR-National Institute of Nutrition (ICMR-NIN) based in Hyderabad, India.
Does this mean I should stop taking Vitamin D2 supplements immediately?
No. ICMR-NIN Director Dr. Bharati Kulkarni emphasized that further clinical research is necessary to fully understand the implications for human supplementation and food fortification programs.
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