HMOX1 and Alzheimer disease: Interestingly, vitamin D supplementation at a dose of 100 μg/kg (three times a week for four weeks) provides brain health effects and improves neuronal synapse and memory, as well as abrogates amyloid beta (Aβ) production by upregulating the Nrf2 pathway and HO-1 and Sirt1 and by downregulating NF-κB pathway and pro-inflammatory cytokines, such as TNF-α and IL-1β in a rodent model of AD [122].