Vegan Diet Studies

[LaurenHW]

@Dr. Jeff
Have you seen these studies on vegan diets? Are they well structured? Who funded them?

I have a strong background in test construction, analysis and looking for flaws! So I feel anyone can prove anything by manipulation. It has to be a very solid well-constructed study for me to accept it.

I’d like & really appreciate your feedback on the studies Jan Allegretti, D.Vet.Hom is presenting and if you have read them and how well-constructed and conducted were these studies.

 

[Dr. Jeff]

Great questions Lauren!

Yes, you can prove almost anything in most studies.

Exactly which studies are you asking about?

 

[Dr. Jean Hofve]

Aha, found it! Here is a "meta-review" of multiple studies on vegan diets for dogs and cats. In general, they found no harm and some possible benefits. However, most of the benefits are reported from owner surveys, which are typically quite biased.

Domínguez-Oliva A, et al. The Impact of Vegan Diets on Indicators of Health in Dogs and Cats: A Systematic Review. Vet. Sci. 2023, 10, 52
Conclusions. This review has found that there is no convincing evidence of major impacts of vegan
diets on dog or cat health. There is, however, a limited number of studies investigating this question and those studies available often use small sample sizes or short feeding durations. There was also evidence of benefits for animals arising as a result of feeding them vegan diets. Much of these data were acquired from guardians via survey-type studies, but these can be subject to selection biases, as well as subjectivity around the outcomes. However, these beneficial findings were relatively consistent across several studies and should, therefore, not be disregarded.
There is an urgent need for large-scale population-based studies to further investigate this question, with a particular focus on assessing the dietary aspects cited to be of particular concern, e.g., taurine and folate. For guardians wishing to feed their pets vegan diets at the current time, based on the available evidence it is recommended that commercially produced vegan diets are used since these are less likely to lead to nutrient imbalances.

 

[Dr. Jean Hofve]

Here's another one, and the problems are evident right off. First, they compared fresh, lightly cooked vegan food to kibble (extruded diet), which we know is not a healthy food. They especially touted how the vegan diet led to decreased cholesterol and triglycerides, which are irrelevant in dogs (who do not get atherosclerosis like humans do). Oddly enough, the organic matter in the vegan diet was less digestible than in the kibble. I'm guessing that the increased processing in the kibble broke down the plant cell walls better than "mildly" cooking. The microbiome was altered in "interesting" ways, but we don't know what that means for health. The one plus is that the vegan diet produced more short-chain fatty acids, which come from breakdown of prebiotic fiber in the colon. Not much in the way of prebiotics in most kibble.

Apparent total tract macronutrient digestibility of mildly cooked human-grade vegan dog foods and their effects on the blood metabolites and fecal characteristics, microbiota, and metabolites of adult dogs
Leah J Roberts, Patricia M Oba, Kelly S Swanson
Journal of Animal Science, Volume 101, 2023, skad093, Apparent total tract macronutrient digestibility of mildly cooked human-grade vegan dog foods and their effects on the blood metabolites and fecal characteristics, microbiota, and metabolites of adult dogs

Vegan, mildly cooked, and human-grade dog foods are increasing in popularity, but few studies have been performed to examine their performance. Our objective was to determine the apparent total tract digestibility (ATTD) of mildly cooked human-grade vegan dog foods and their effects on blood metabolites and fecal microbiota, characteristics, and metabolites of dogs. Two mildly cooked human-grade vegan dog diets and a chicken-based extruded dog diet were tested using 12 healthy adult dogs in a replicated 3 × 3 Latin Square design. All diets were highly digestible, with all macronutrients having digestibility values >80%. Vegan diets had higher ATTD of fat, but lower ATTD of organic matter than the extruded diet. Dogs consuming vegan diets had lower circulating cholesterol, triglycerides, platelets, and neutrophils than dogs consuming the extruded diet. Dogs consuming vegan diets had lower fecal dry matter percentages and phenol and indole concentrations, and higher fecal short-chain fatty acid concentrations than those consuming the extruded diet. Finally, ~20 bacterial genera were altered between dogs consuming vegan and extruded diets. In conclusion, the mildly cooked human-grade vegan dog foods tested performed well, resulting in desirable fecal characteristics, high ATTD, adequate serum chemistries, positive changes to serum lipids and fecal metabolites, and interesting changes to fecal microbiota.