Periodic Reporting for period 5 - FastBio (A genomics and systems biology approach to explore the molecular signature and functional consequences of long-term, structured fasting in humans)
Reporting period: 2024-04-01 to 2025-03-31
Dietary intake shapes the growth of organisms, enables organ development and maintenance, affects immune system function and ultimately influences health and lifespan. Although diet has an enormous impact on health, consensus about how what we eat affects our biology remains largely elusive. However, there is consensus that our diet has a much more pervasive role than previously thought in modulating molecular mechanisms governing susceptibility to diseases such as type 2 diabetes, cardiovascular disease and cancer. The biological mechanisms linking diet to disease however remain unclear.
To address the gap in our knowledge, we established the FastBio (religious Fasting Biology) study which explores the biological impact of a dietary pattern involving periodic dietary restriction (DR) of animal products. We carried out in-depth molecular characterisation of a unique group of individuals from Greece who alternate between omnivory and animal product DR for religious reasons. These individuals abstain from meat, fish, dairy products and eggs for ~190 days annually, in a consistent and highly structured pattern involving four extended periods of DR throughout the year, and DR on Wednesdays and Fridays. We compared findings to a continuously omnivorous group of individuals studied in parallel. Participants were profiled at two timepoints: T1 (autumn), covering a period of omnivory for both groups, and T2 (spring), covering a 3-4-week period of DR, during Lent.
We aimed to investigate how animal product DR affects:
1) Health-related clinical chemistry biomarkers and complete blood counts
2) Molecular traits (blood metabolites, gene expression and protein levels, the gut microbiome) and how our genetic makeup can influence their levels
3) Immune system cells and their function
We found that short-term DR can reprogram biological pathways resulting in substantial metabolic, immune and molecular changes with predominantly positive effects on health. However, further investigation is needed to clarify both positive and potentially negative consequences and to better understand how genetic and environmental factors, such as diet and seasonal variation, interact to influence disease risk. Importantly, our results indicate that dietary recommendations may not have uniform effects across individuals due to differences in genetic background. These insights have important implications for clinical practice, supporting the development of precision nutrition and personalised strategies for disease prevention. Additionally, we have identified promising molecular candidates for therapeutic evaluation, including targets for drugs designed to mimic diet-associated molecular responses that support healthy aging. Finally, our data reveal diet-driven changes in the abundance of potentially druggable targets, suggesting that dietary interventions could be leveraged to optimise pharmacological outcomes.
To address the gap in our knowledge, we established the FastBio (religious Fasting Biology) study which explores the biological impact of a dietary pattern involving periodic dietary restriction (DR) of animal products. We carried out in-depth molecular characterisation of a unique group of individuals from Greece who alternate between omnivory and animal product DR for religious reasons. These individuals abstain from meat, fish, dairy products and eggs for ~190 days annually, in a consistent and highly structured pattern involving four extended periods of DR throughout the year, and DR on Wednesdays and Fridays. We compared findings to a continuously omnivorous group of individuals studied in parallel. Participants were profiled at two timepoints: T1 (autumn), covering a period of omnivory for both groups, and T2 (spring), covering a 3-4-week period of DR, during Lent.
We aimed to investigate how animal product DR affects:
1) Health-related clinical chemistry biomarkers and complete blood counts
2) Molecular traits (blood metabolites, gene expression and protein levels, the gut microbiome) and how our genetic makeup can influence their levels
3) Immune system cells and their function
We found that short-term DR can reprogram biological pathways resulting in substantial metabolic, immune and molecular changes with predominantly positive effects on health. However, further investigation is needed to clarify both positive and potentially negative consequences and to better understand how genetic and environmental factors, such as diet and seasonal variation, interact to influence disease risk. Importantly, our results indicate that dietary recommendations may not have uniform effects across individuals due to differences in genetic background. These insights have important implications for clinical practice, supporting the development of precision nutrition and personalised strategies for disease prevention. Additionally, we have identified promising molecular candidates for therapeutic evaluation, including targets for drugs designed to mimic diet-associated molecular responses that support healthy aging. Finally, our data reveal diet-driven changes in the abundance of potentially druggable targets, suggesting that dietary interventions could be leveraged to optimise pharmacological outcomes.
FastBio is a unique bioresource offering in-depth biological information from a rare study population and enabling us to address how environmental factors such as diet affect our biology. Our study comprises 200 individuals who practice animal product DR and 211 individuals who are continuously omnivorous. We collected detailed data at two timepoints, including measurements of body composition, medical history, lifestyle, blood biomarkers and immune cell profiles. We also examined the genetic makeup of participants, measured metabolites, proteins and gene activity in blood, and explored gut microbiome composition.
DR was associated with reductions in total and non-HDL cholesterol, improved biomarkers of liver and kidney function, and lower markers of inflammation. This rewiring occurred alongside changes in immune cell composition and enhanced anti-inflammatory cytokine responses. While most biomarker changes were in a direction suggesting positive health effects, we also identified changes suggesting potentially negative effects on bone health. The gut microbiome responded dynamically to DR, adapting to altered dietary intake. Although overall microbial diversity declined, a change often considered unfavourable, we suggest that this is an adaptative response to a less diverse diet. DR was associated with a decrease in certain pro-inflammatory bacterial taxa and with increased activity of microbes synthesizing vitamin B2, a micronutrient rich in animal products.
At the molecular level, DR modulated the expression of genes and proteins involved in critical physiological pathways, including cholesterol transport, immune signaling and metabolic regulation. Some of these molecules are known drug targets, while others represent promising candidates for therapeutic development. We also found that diet can influence the way genes and proteins regulate their expression levels in blood. This was discovered for genes with pivotal roles for health including cholesterol production, repair of damaged proteins, energy regulation and protection of chromosome ends.
Beyond dietary effects, we revealed seasonal changes primarily for immune-related traits. Although seasonal trends are well recognized in conditions such as cardiovascular disease, allergies and autoimmune disorders, the underlying mechanisms remain poorly understood. Our findings highlight seasonal changes that may contribute to our understanding of these trends in disease risk.
DR was associated with reductions in total and non-HDL cholesterol, improved biomarkers of liver and kidney function, and lower markers of inflammation. This rewiring occurred alongside changes in immune cell composition and enhanced anti-inflammatory cytokine responses. While most biomarker changes were in a direction suggesting positive health effects, we also identified changes suggesting potentially negative effects on bone health. The gut microbiome responded dynamically to DR, adapting to altered dietary intake. Although overall microbial diversity declined, a change often considered unfavourable, we suggest that this is an adaptative response to a less diverse diet. DR was associated with a decrease in certain pro-inflammatory bacterial taxa and with increased activity of microbes synthesizing vitamin B2, a micronutrient rich in animal products.
At the molecular level, DR modulated the expression of genes and proteins involved in critical physiological pathways, including cholesterol transport, immune signaling and metabolic regulation. Some of these molecules are known drug targets, while others represent promising candidates for therapeutic development. We also found that diet can influence the way genes and proteins regulate their expression levels in blood. This was discovered for genes with pivotal roles for health including cholesterol production, repair of damaged proteins, energy regulation and protection of chromosome ends.
Beyond dietary effects, we revealed seasonal changes primarily for immune-related traits. Although seasonal trends are well recognized in conditions such as cardiovascular disease, allergies and autoimmune disorders, the underlying mechanisms remain poorly understood. Our findings highlight seasonal changes that may contribute to our understanding of these trends in disease risk.
Through FastBio we revealed that DR boosts levels of FGF21, a hormone regulating metabolism and energy balance. While animal studies have shown strong benefits of FGF21 administration for obesity-associated disease, human trials have had relatively limited success and human FGF21 biology remains poorly understood. We found that in addition to boosting FGF21 levels, DR reduced levels of an enzyme that breaks it down suggesting that the hormone may stay active for longer. We also identified 55 proteins potentially linked to FGF21, including some with known roles and many new candidates for future research. Additionally, we found a link between a genetic regulator of FGF21 levels and a specific subset of immune cells, highlighting key metabolic roles for immune system cells.
We also revealed that genetic differences can influence how people respond to diet. For the first time in humans we showed that gene activity and protein levels can be altered by diet in individuals harbouring specific genetic variants. Proteins involved in cholesterol and methionine metabolism for example were found at altered levels under DR, most likely to compensate for lower dietary intake of these nutrients, but only in individuals bearing specific genetic variants. One of these diet-responsive variants controlling a protein that synthesises cholesterol, was also linked to obesity risk. This suggest that some people may be more vulnerable to weight gain depending on the interaction between their genes and diet.
Our study also revealed seasonal shifts in immune-related traits and in regulation of gene and protein levels. Numbers of neutrophils, an immune cell type, decreased in spring, while a gene involved in their control was found to lose its genetic regulator during this period. This suggests that genetic makeup and seasonality may interact to determine gene activity and protein levels. Notably, certain seasonal effects were only seen in the continuously omnivorous group, suggesting that diet may buffer the immune system from some seasonal changes.
We also revealed that genetic differences can influence how people respond to diet. For the first time in humans we showed that gene activity and protein levels can be altered by diet in individuals harbouring specific genetic variants. Proteins involved in cholesterol and methionine metabolism for example were found at altered levels under DR, most likely to compensate for lower dietary intake of these nutrients, but only in individuals bearing specific genetic variants. One of these diet-responsive variants controlling a protein that synthesises cholesterol, was also linked to obesity risk. This suggest that some people may be more vulnerable to weight gain depending on the interaction between their genes and diet.
Our study also revealed seasonal shifts in immune-related traits and in regulation of gene and protein levels. Numbers of neutrophils, an immune cell type, decreased in spring, while a gene involved in their control was found to lose its genetic regulator during this period. This suggests that genetic makeup and seasonality may interact to determine gene activity and protein levels. Notably, certain seasonal effects were only seen in the continuously omnivorous group, suggesting that diet may buffer the immune system from some seasonal changes.