Yes, provided the food is properly formulated! A three-month, randomized study from the University of Guelph showed that dogs on a plant-based diet with vitamin D2 maintained the exact same vitamin D levels and bone density as dogs on a traditional meat-based diet with vitamin D3 (Dodd et al., 2024). Below, we explain why this question is so important and exactly what the research demonstrated.
Why is vitamin D a point of concern for dogs in the first place?
Here is a surprising fact: unlike you as a human, your dog cannot produce vitamin D via the sun. While your skin produces vitamin D as soon as it is exposed to sunlight, the skin of dogs and cats lacks the necessary building blocks for this (How, Hazewinkel, & Mol, 1994). A dog is therefore 100% dependent on the vitamin D that it receives through its diet.
This is not a specific "plant-based food" issue; it applies to every dog food, plant-based or not! The question is not whether dog food should contain vitamin D, but from which source.
What is the difference between vitamin D2 and D3?
Vitamin D3 (cholecalciferol) usually comes naturally from animal sources and is used in most traditional dog foods. Vitamin D3 can also be obtained from a few vegan sources, which is what we use at VerdaDog. Vitamin D2 (ergocalciferol) comes from plant and fungal sources, such as yeast, making it the logical choice for a completely plant-based recipe.
For a long time, it was simply unclear whether vitamin D2 works just as effectively in dogs as D3 (Dodd et al., 2024). That is precisely the question the researchers from Guelph wanted to answer.
What did the three-month study by Dodd et al. (2024) find?
Sixty-one healthy adult dogs took part in this randomized, blinded study. Thirty-one dogs were given a plant-based diet with vitamin D2 for 3 months; thirty dogs were given a meat-based diet with vitamin D3 (Dodd et al., 2024). Blood levels were measured at both the start and the end of the study, and bone composition was scanned with a DEXA scan, the same precision technique used in humans to measure bone density.
The results were clearly positive. Dogs on the plant-based food did show a shift from D3 to D2 forms in the blood, which is logical since that was the vitamin D source in their food. However, the total amount of vitamin D in the body remained virtually the same as that of the dogs on the meat-based food (Dodd et al., 2024). Bone mineral density and bone mass also did not change compared to the starting values. In short: vitamin D2 maintained the vitamin D status and bone health of these dogs just as well as D3 did.
The researchers concluded that vitamin D2 proved effective in maintaining both total vitamin D concentration and bone mineralization, and that the plant-based food was comparable to the meat-based food in this regard (Dodd et al., 2024).
What does this mean for my dog?
The issue is not "is plant-based food good for my dog's vitamin D status," but rather "is the vitamin D in this specific food well-dosed and in the right form." That is exactly why recipe formulation and dosage are so important, regardless of whether the food is plant-based or not.
One thing is good to know: this study lasted 3 months and was conducted on healthy, adult dogs. For growing puppies, whose bone development is extra sensitive to nutrition, separate caution and specific research are required.
What does this mean for VerdaDog nutrition?
Vitamin D is a fat-soluble vitamin, which means too much of it can accumulate in the body. That is precisely why we at VerdaDog critically monitor both the form and dosage of vitamin D in our recipes. Curious about the composition of our kibble? Take a look here! Do you have a specific question about your dog's diet? Check our FAQ page or contact us.
Can my dog get a vitamin D deficiency from plant-based food?
Not if the food is properly formulated. Research shows that vitamin D2 maintains the vitamin D status and bone health of dogs just as well as vitamin D3, provided it is dosed correctly (Dodd et al., 2024). It is also important to emphasize that there are completely plant-based sources of both vitamin D2 and vitamin D3.
Why can't my dog produce vitamin D via sunlight, while I can?
Dogs (and cats) lack the right building blocks in their skin to produce vitamin D under the influence of sunlight (How et al., 1994). This is why a dog, unlike a human, is completely dependent on vitamin D from its diet.
Does this research also apply to puppies or older dogs?
No, this study lasted 3 months and was conducted on healthy, adult dogs. For puppies in the growth phase, extra caution and targeted research are required, as bone development is more sensitive to nutrition during that time.
Should I give my dog extra vitamin D supplements on top of their food?
No, we advise against this without consulting a veterinarian. Vitamin D is fat-soluble and can accumulate, meaning too much supplementation can actually be harmful. A complete and well-formulated food does not need extra supplementation.
About the author
David is the founder of VerdaDog. He grew up with a dog that struggled with allergies, and that set him thinking about how he could prevent that in his own dog. He has been eating a plant-based diet for over ten years himself, and that interest in nutrition, for himself and his dog, forms the basis of VerdaDog. This article is written based on peer-reviewed research. David does not claim veterinary or scientific expertise and always refers to a veterinarian for medical advice.
Literature
Dodd, S. A. S., Adolphe, J., Dewey, C., Khosa, D., Abood, S. K., & Verbrugghe, A. (2024). Efficacy of vitamin D2 in maintaining serum total vitamin D concentrations and bone mineralisation in adult dogs fed a plant-based (vegan) diet in a 3-month randomised trial. British Journal of Nutrition, 131(3), 391–405. https://doi.org/10.1017/S0007114523001952
How, K. L., Hazewinkel, H. A. W., & Mol, J. A. (1994). Dietary vitamin D dependence of cat and dog due to inadequate cutaneous synthesis of vitamin D. General and Comparative Endocrinology, 96(1), 12–18. https://doi.org/10.1006/gcen.1994.1154
