Researchers from Johns Hopkins Medicine and the National Institute on Aging at the National Institutes of Health report findings from a study involving 40 overweight and insulin-resistant older adults. These participants were randomly allocated to one of two diet plans: intermittent fasting or a standard healthy diet endorsed by the U.S. Department of Agriculture (USDA). This study sheds light on how each diet may impact brain health.
Insulin resistance is commonly seen in individuals with obesity and is a precursor to type 2 diabetes. It’s also linked to a higher risk of cognitive impairments like Alzheimer’s disease. Therefore, diet-based interventions are frequently explored as potential means to mitigate these risks. Previous research from Johns Hopkins using animal models indicated that intermittent fasting might bolster cognitive functions and enhance insulin sensitivity. The current study, published on June 19 in the journal Cell Metabolism, extends these findings to human subjects, mainly focusing on men and women at risk of cognitive decline. It provides a “blueprint” for utilising a comprehensive set of biomarkers to gauge dietary impacts. This includes the analysis of extracellular vesicles, minuscule particles released from neurons that play a crucial role in cellular communication. These cysts were collected from participants over an eight-week trial period while they adhered to their respective diets.
The findings indicate that both dietary approaches were beneficial, leading to reduced insulin resistance and enhanced cognitive functions such as memory and executive abilities. However, the improvements were more pronounced in those following the intermittent fasting regimen. Mark Mattson, Ph.D., an adjunct professor of neuroscience at Johns Hopkins University and a former chief at the National Institute on Aging, suggests that these findings could inspire further extensive studies incorporating these brain health markers, thereby opening up new avenues for research and discovery in the field of brain health.
Participants were drawn between June 2015 and December 2022, undergoing four assessments at the National Institute on Aging’s facilities at MedStar Harbor Hospital in Baltimore. Of these, 20 were assigned to the intermittent fasting diet, which limited caloric intake to 25% of daily recommendations for two consecutive days each week. They followed the USDA’s guidelines for the rest of the week, which promote a balanced diet of fruits, vegetables, whole grains, lean proteins, and low-fat dairy while restricting added sugars, saturated fats, and sodium. The remaining 20 participants adhered to the USDA’s diet throughout the week.
The average age of the study participants was 63, and the group included a diverse demographic, ensuring that the findings applied to a wide range of individuals. All participants were clinically obese and exhibited insulin resistance. The study showed that both diets effectively lowered insulin resistance and enhanced metabolic health metrics such as body weight, BMI, waist circumference, and blood lipid levels. Cognitive functions improved significantly, with those on the intermittent fasting diet showing roughly 20% greater enhancement in executive functions and memory.
Some participants experienced minor side effects like constipation, loose stools, and occasional headaches. Moreover, the study noted elevated levels of neurofilament proteins, which are associated with neural structure, particularly in the intermittent fasting group. The implications of these elevated protein levels for brain health remain uncertain. Still, as highlighted by Dr. Mattson, they present a potential avenue for future research into the neuroplastic effects of intermittent fasting.
More information: Dimitrios Kapogiannis et al, Brain responses to intermittent fasting and the healthy living diet in older adults, Cell Metabolism. DOI: 10.1016/j.cmet.2024.05.017
Journal information: Cell Metabolism Provided by Johns Hopkins Medicine
