Imagine switching to a completely vegan or ketogenic diet and seeing your immune system respond almost instantly. That’s exactly what researchers at the National Institutes of Health (NIH) uncovered in a groundbreaking study. The research revealed how quickly our body’s defences—both natural and adaptive immunity—can adapt to dietary changes, offering insights into the connection between food, immunity, and overall health.
Whether you’re considering a plant-based lifestyle or a high-fat, low-carb regime, this study highlighted how these diets impact not just your gut but your entire immune system.
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Vegan vs. Keto Diet
The vegan diet, rich in carbohydrates (75%) and low in fat (10%), triggered responses linked to innate immunity—the body’s first line of defence against pathogens. In contrast, the keto diet, high in fat (76%) and low in carbohydrates (10%), activated adaptive immunity, which develops from exposure to pathogens and vaccines.
What did the study find?
Participants experienced noticeable changes in their metabolism, microbiome, and immune responses:
Vegan Diet
Enhanced pathways linked to innate immunity, including antiviral responses.
Promoted red blood cell pathways, possibly due to higher iron content in the diet.
Impacted gut bacteria composition, favouring species associated with plant-based diets.
Keto Diet
Stimulated adaptive immunity by activating T and B cell pathways.
Increased blood plasma proteins and affected processes in tissues such as the brain, blood, and bone marrow.
Altered amino acid metabolism, likely reflecting higher protein intake.
More about the study
The study was conducted under controlled conditions at the NIH Clinical Centre. Participants, diverse in ethnicity, gender, age, and BMI, consumed unlimited portions of each diet during the study. Biological samples, including blood, urine, and stool, were collected to monitor biochemical, cellular, metabolic, and immune changes using a “multi-omics” approach.
Both diets caused significant shifts in the microbiome, showing diet-specific changes in gut bacteria linked to immunity. Notably, participants on the vegan diet consumed fewer calories compared to those on the keto diet, emphasising the dietary differences in macronutrient composition.
