The level of brain-derived neurotrophic factor (BDNF) in circulation is a topic of extensive research for potential intervention. Increased BDNF has positive effects on neurogenesis, which is crucial for memory function and maintaining brain tissue. Exercise, butyrate supplementation, and interventions targeting the gut microbiome can increase BDNF levels, but the effects of intermittent fasting and calorie restriction are varied. A systematic review on the relationship between intermittent fasting and BDNF levels suggests that while some studies show an increase in BDNF, others show a decrease or no significant change. More research is needed to fully understand the impact of intermittent fasting on BDNF and cognitive function.
The potential positive interaction between intermittent fasting (IF) and brain-derived neurotrophic factor (BDNF) on cognitive function has been widely discussed. This systematic review tried to assess the efficacy of interventions with different IF regimens on BDNF levels and their association with cognitive functions in humans. Interventions with different forms of IF such as caloric restriction (CR), alternate-day fasting (ADF), time-restricted eating (TRE), and the Ramadan model of intermittent fasting (RIF) were targeted.
A systematic review was conducted for experimental and observational studies on healthy people and patients with diseases published from January 2000 to December 2023. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statements (PRISMA) for writing this review. Sixteen research works conducted on healthy people and patients with metabolic disorders met the inclusion criteria for this systematic review. Five studies showed a significant increase in BDNF after the intervention, while five studies reported a significant decrease in BDNF levels, and the other six studies showed no significant changes in BDNF levels due to IF regimens. Moreover, five studies examined the RIF protocol, of which, three studies showed a significant reduction, while two showed a significant increase in BDNF levels, along with an improvement in cognitive function after RIF.
The current findings suggest that IF has varying effects on BDNF levels and cognitive functions in healthy, overweight/obese individuals and patients with metabolic conditions. However, few human studies have shown that IF increases BDNF levels, with controversial results. In humans, IF has yet to be fully investigated in terms of its long-term effect on BDNF and cognitive functions. Large-scale, well-controlled studies with high-quality data are warranted to elucidate the impact of the IF regimens on BDNF levels and cognitive functions.
