July 18, 2024

Switching to Vegan or Keto Diets Drastically Affects Immune System, Study Finds

A recent study conducted by researchers at the National Institutes of Health (NIH) has revealed that switching to either a vegan or ketogenic (keto) diet can rapidly and significantly impact the immune system. The study, published in the journal Nature Medicine, closely monitored the immune system changes and metabolic shifts of individuals who sequentially followed vegan and keto diets for two weeks each, in random order.

The findings of the study indicated that the vegan diet triggered responses linked to innate immunity—the body’s preliminary defense mechanism against pathogens. On the other hand, the keto diet stimulated responses associated with adaptive immunity, which is the immune system’s specific defense against certain pathogens that developed over time through exposure and vaccinations.

Additionally, the study observed metabolic changes and alterations in participants’ microbiomes—the communities of bacteria residing in the gut. However, further research is required to determine the potential benefits or risks of these changes and their effect on nutritional interventions for diseases like cancer or inflammatory conditions.

The impact of different diets on the human immune system and microbiome has not yet been fully understood by scientists. Therapeutic nutritional interventions, which involve modifying diets for improved health, are still not well-researched, and only a limited number of studies have directly compared the effects of more than one diet. The keto diet is a low-carbohydrate, high-fat diet, while the vegan diet excludes animal products and is typically high in fiber and low in fat.

The study was conducted by researchers from the NIH’s National Institute of Allergy and Infectious Diseases (NIAID) and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) at the Metabolic Clinical Research Unit in the NIH Clinical Center. The study included 20 ethnically diverse participants of various races, genders, body mass indices (BMI), and ages.

During the study, each participant adhered to one diet (vegan or keto) for two weeks, consuming as much as desired, followed by switching to the other diet for another two weeks. Participants on the vegan diet, which consisted of approximately 10% fat and 75% carbohydrates, consumed fewer calories compared to those on the keto diet, which contained about 76% fat and 10% carbohydrates.

Throughout the study period, blood, urine, and stool samples were collected from the participants for analysis. The effects of the diets were assessed using a multi-omics approach, involving the analysis of multiple datasets to evaluate biochemical, cellular, metabolic, and immune responses, as well as changes in the microbiome. The participants were closely monitored on-site for the entire month-long study, ensuring precise control of the dietary interventions.

The transition to either the vegan or keto diet resulted in notable changes in all participants. The vegan diet notably influenced pathways associated with innate immunity, particularly antiviral responses. Conversely, the keto diet led to significant increases in biochemical and cellular processes related to adaptive immunity, such as pathways associated with T and B cells.

Moreover, the keto diet affected the levels of a larger number of proteins in the blood plasma compared to the vegan diet, affecting proteins from a wider range of tissues, including blood, brain, and bone marrow. The vegan diet, on the other hand, promoted red blood cell-linked pathways, including those involved in heme metabolism, which could be attributed to the higher iron content in this diet.

1. Source: Coherent Market Insights, Public sources, Desk research
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