Another study that will probably make me plenty of new enemies among the anti-retinol crowd. I am posting it here because one of the main claims of the anti-retinol groups is that dietary restriction of vitamin A not only has no negative effects on health, but is actually highly beneficial. Well, it seems that when it comes to brain health at least, the opposite is true. It took only 12 weeks of vitamin A restriction to establish AD pathology, while the same amount of time supplementing vitamin A was sufficient to produce strong beneficial effects. Crucially, vitamin A restriction elevated biomarkers of gut permeability (D-lactate and DAO), which matches with the post I just did on endotoxin/LPS being a major causative factor in AD. Conversely, vitamin A supplementation was effective at restoring the gut barrier, and subsequently preserving cognition even in animals with already established AD.
https://www.frontiersin.org/articles/10.3389/fnut.2024.1367086/full
“…In the present study, researchers investigated the effects of dietary vitamin A on the intestinal transcriptome, inflammation, gut microbiota, and amyloid-β (Aβ) pathology. Thirty APP/PS1 mice (AD mouse model) were randomly assigned to three groups based on body weight. Mice received a diet with deficient (VAD), normal (VAN), or enriched (VAS) levels of vitamin A. Body weight and food intake were recorded every week.”
“…Mice in the VAN group could directly locate the platform and move to its position even when removed. These mice took less time to find the platform than other groups. Moreover, the VAS group took less time than the VAD group. There were no significant differences in the time spent finding the platform between VAS and VAN groups. When the platform was removed, the VAN group repeatedly crossed the platform area. Mice in the VAD group showed significantly greater Aβ deposition in the brain than in other groups. The VAS group also had higher Aβ deposition than the VAN group, albeit not statistically significant. The Shannon index was higher in the VAS and VAN groups than in the VAD group; however, it was similar between the VAS and VAN groups. VAN and VAS groups had greater microbial diversity than the VAD group. Overall, 571 genes with differential expression were identified between the VAS and VAD groups. Between VAN and VAD groups, 313 differentially expressed genes were identified. Further, there were 243 genes with differential expression between VAN and VAS groups. DAO and D-lactate levels were significantly elevated in the VAD group compared to the VAS and VAN groups. Mice in the VAD group exhibited more significant levels of inflammatory cytokines than other groups.
“…In sum, the study showed that a 12-week VAD diet reduced serum levels of retinol, impaired cognition, and increased Aβ pathology in mice. On the contrary, a diet enriched with vitamin A increased retinol, reduced Aβ, and preserved cognition. Overall, the findings highlight the significance of vitamin A in AD pathology and behavior.”
