Dietary Changes Rapidly Alter the Immune System: Comparing Vegan and Ketogenic Diets

We have clearly entered a new era when mainstream science has come to embrace the notion that nutrition exerts significant influence over various physiological functions, including immune regulation, and may serve as a therapeutic avenue for diseases like cancer, autoimmune conditions and chronic inflammation. Emerging research has shown that vegan and vegetarian diets can reduce inflammation and heart disease risk, while ketogenic diets have proven beneficial for certain neurological conditions, like epilepsy, Parkinson’s autism, and even Alzheimer’s disease, by reducing neuroinflammation. Despite these findings, the precise effects of these diets on human immunity remain unclear. The impact of nutrition extends beyond nutrient intake to include changes in the gut microbiome, a critical component of overall health.

While animal research has demonstrated a clear link between diet, microbiome, and immune function, understanding these effects in humans remains incomplete. But the exciting news is that this research is happening, laying the groundwork for personalized nutritional strategies that promote health.

In an exciting new study, researchers aimed to evaluate the effects on the immune system of two popular diets, a vegan program and a ketogenic diet. This research, conducted from April 2019 to March 2020 at the National Institutes of Health (NIH) Clinical Center, enrolled participants aged 18 to 50, who were free from metabolic and cardiovascular diseases. Informed consent was obtained, and participants were randomly assigned to follow either a vegan or ketogenic diet for two weeks, followed by a switch to the alternate diet. Meals were strictly prepared to meet dietary guidelines, and participants’ compliance was monitored.

The study investigated gut microbiome changes through stool sample analysis. Blood samples were processed to analyze immune and metabolic effects.

Twenty participants completed the cross-over study, alternating between a high-fat, low-carbohydrate ketogenic diet and a low-fat, high-carbohydrate vegan diet for just two weeks each. Both diets were based on non-starchy vegetables but differed fundamentally: the ketogenic diet included animal products, whereas the vegan diet emphasized plant-based nutrients, resulting in significant differences in fatty acid and amino acid intake.

Analyses revealed that both diets induced rapid immune adaptations. There were significant shifts in immune cell types, regardless of diet order. The ketogenic diet increased regulatory T cells and natural killer (NK) cells, while the vegan diet enhanced activated T helper and NK cells.

Whole blood RNA sequencing revealed distinct gene expression linked to each diet, with the ketogenic diet upregulating T-cell activation pathways. Microbiome analysis showed significant composition changes, particularly after the ketogenic diet, which affected amino acid and pathways involved in vitamin synthesis.

The blood studies confirmed that dietary interventions dramatically altered host metabolism, especially lipid profiles, underscoring the profound impact of dietary patterns on immune and metabolic health.

I know this all sounds pretty technical, but here’s the importance of this work. First, the dramatic shifts in the blood markers involved both in metabolism and immunity changed in just 2 weeks. That’s encouraging for all of us. Second, these diets, shown to have such an impact on so many biomarkers, are not esoteric or hard to implement. There was no requirement for any exotic supplement or biohacking gear.

Finally, isn’t it great that this type of research is finally being pursued?