Correlation Between Dietary Nutrition and Glymphatic System Activity in Healthy Participants.

Background Dietary nutrition is an important approach to the prevention and treatment of the physical and mental states of humans. Nowadays, many studies show the neuroprotective and antioxidative effects of nutrients, such as B vitamins, zinc, and iron, on the central nervous system (CNS). However, there were no studies focusing on the relationships between the serum concentration of nutrients and the brain glymphatic system activity and macroscopic waste clearance system, including reactive oxygen species. Objectives This study tries to evaluate the relationships between them using diffusion tensor image analysis along the perivascular space (DTI‑ALPS) index as the proxy of glymphatic system activity. Methods The subjects were 159 healthy participants who underwent 1.5-Tesla DTI (diffusion tensor imaging) and blood sampling. We computed the DTI‑ALPS index and estimated the relationships between the DTI‑ALPS index and the serum concentrations of vitamin B6, vitamin B12, folate, zinc, ferritin, and iron. Results There were significant positive correlations of the DTI‑ALPS index with age and sex. Additionally, we found that age, sex, and serum zinc level were good independent variables that predicted the dependent variable, the DTI‑ALPS index, as revealed by multiple regression analyses. Conclusion We found a significant correlation between brain clearance system activity and serum zinc levels in healthy participants. Though zinc is known to play an important physiological role in the CNS, excessive zinc accumulation or zinc deficiency might induce neurodegeneration. Further works with varying serum zinc concentrations would reveal the neuroprotective effect of zinc in its proper concentration.