Vitamin D3 ‘more effective’ than D2 for restoring muscle, heart health: ICMR study

Vitamin D occurs in nature in two forms: vitamin D3 and vitamin D2.

While D3 is synthesised through sun/UV exposure and obtained primarily from animal-based foods such as eggs, fish and organ meats and from supplements, D2 is derived from wild, cultivated or sun-dried mushrooms, UV-B-irradiated yeast, plant-based sources and some dietary supplements.

For food fortification, both D2 and D3 are used. However, D2 is a more preferred fortificant in certain countries due to widespread vegetarianism or among people who follow a strict vegan diet.

“Vitamin D plays an important role in modulating skeletal muscle mass, structure, and function, however, the differential impact of D2 and D3 remains inconclusive. In this study, we found that D3 has a greater impact than D2 in improving skeletal muscle size and function during both maintenance and recovery phase,” the study said.

While both forms are used in supplements and food fortification, evidence on whether the two forms have similar effects beyond bone health has remained limited.

To study the differences between the two forms, the researchers used weaning male Sprague-Dawley rats and fed them diets containing vitamin D2, vitamin D3, a combination of both, or a vitamin D-deficient diet.

The researchers assessed body composition, muscle strength, skeletal muscle structure and metabolism, and markers related to cardiac function.

Dr Bharati Kulkarni, Director, ICMR-NIN, said, “The findings indicate that vitamin D3 may be more effective than vitamin D2 in maintaining and restoring skeletal muscle and cardiac functions.”

She said 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.

According to the World Health Organisation-Food and Agriculture Organisation (WHO-FAO), micronutrient supplementation is the fastest method to improve the micronutrient status of populations, while fortification can be a cost-effective public health intervention with a sustained impact.