A NIH study finds distinct immune responses occur quickly when diets change. This study was conducted by Yasmine Belkaid, now President of the Institut Pasteur (Paris), and her former research team at the US National Institute of Allergy and Infectious Diseases (NIAID).
A study observes rapid and distinct immune system changes when people switched to a vegan diet (animal product-free, high in fiber and low in fat) or a ketogenic diet (also called keto; high-fat, low-sugar). Researchers at the NIH’s National Institute of Allergy and Infectious Diseases (NIAID) and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) closely worked to achieve this study. It included Yasmine Belkaid, former chief of the NIAID Laboratory of Host Immunity and Microbiome, now president of the Institut Pasteur, Paris, France.
Scientific understanding of how different diets impact the human immune system and microbiome is limited. Therapeutic nutritional interventions—which involve changing the diet to improve health—are not well understood, and few studies have directly compared the effects of more than one diet.
Scientists closely monitored the biological responses of people eating vegan and keto diets for two weeks each. They have found that :
- The vegan diet prompted responses linked to innate immunity —the body’s generalized first line of defense against pathogens—.
- The vegan diet significantly promoted pathways linked to the innate immune system, including antiviral responses.
- The vegan diet promoted red blood cell-linked pathways, including those involved in heme metabolism, which could be due to the higher iron content of this diet.
In the study, the vegan diet contained about 10% fat and 75% carbohydrates. Those on the vegan diet chose to consume fewer calories than those on the keto diet.
- The keto diet prompted responses associated with adaptive immunity —pathogen-specific immunity built through vaccination and exposures in daily life—.
- The keto diet led to significant increases in biochemical and cellular processes linked to adaptive immunity, such as pathways associated with T and B cells.
- In the keto diet, the proteins — found in abundance in the blood plasma — are more diverse than in the vegan diet; the keto diet also affects protein levels from a wider range of tissues, such as the blood, brain and bone marrow.
In the study, the keto diet contained 76% fat and 10% carbohydrates.
Additionally, both diets caused changes in the microbiomes of the participants. Metabolic changes and shifts in the communities of bacteria living in the gut, also known as microbiomes, were indeed observed.
More research is needed to understand what implications these observations could have on nutritional interventions for diseases such as cancer or inflammatory conditions.
From March 1, 2024, Professor Yasmine Belkaid – in addition to her role as President of the Institut Pasteur (Paris) – will head the Meta-organism Unit, part of the Immunology Department within the Institut Pasteur.