Background: Dementia is a syndrome characterized by progressive cognitive impairment that interferes with independent function in daily activities. Symptoms of dementia depend on its cause and vary greatly between individuals. There is extensive evidence supporting a relationship between diet and cognitive functions. This systematic review studies the efficacy of using vitamin supplements in the diet as a solution to nutritional deficiencies and the prevention of dementia and mild cognitive impairment. Methods: An intensive search of different databases (PubMed, Web of Science, and Cochrane CENTRAL) was performed. Articles that were published between 2011 and November 2021 were retrieved using the mentioned search strategy. This systematic review has been conducted according to the PRISMA statement. Results: Folic acid supplementation proved to have better outcomes on cognitive tests than their respective control groups. The combined supplementation of folic acid and vitamin B12 showed some discrepancies between studies. Thiamine as supplementation did not only prove to have a positive impact on cognitive performance when given alone but also when given in combination with folic acid. Regarding vitamin D supplementation, the results observed were not so encouraging. A concomitant supplementation of low-dose vitamin E and vitamin C was also not associated with an improvement of cognitive function. Conclusions: The findings of this systematic review suggest that supplementation of B Complex vitamins, especially folic acid, may have a positive effect on delaying and preventing the risk of cognitive decline. Ascorbic acid and a high dose of vitamin E, when given separately, also showed positive effects on cognitive performance, but there is not sufficient evidence to support their use. The results of vitamin D supplementation trials are not conclusive in assessing the potential benefits that vitamin D might have on cognition.

Background: Due to the lack of an etiologic treatment for SARS-CoV-2 and the difficulties involved in developing new drugs, some drugs already approved for other diseases or with efficacy against SARS and MERS, have been used in patients with COVID-19. This systematic review aims to summarize evidence on the efficacy and safety of five antivirals applied to patients with COVID-19, that have proven to be effective either in vitro studies or in studies on SARS-CoV and MERS.; Methods: An intensive search of different databases (Pub Med, WoS, MEDLINE and Cochrane COVID-19 Study Register) has been carried out until the end of April 2021. This systematic review has been conducted according to the PRISMA statement. From each of the included studies, the characteristics of the intervention and comparison groups, demographic data and results were extracted independently; Results: Remdesivir is well tolerated and helps to accelerate clinical improvement but is ineffective in reducing mortality. Favipiravir is safe and shows promising results regarding symptom resolution but does not improve viral clearance. The use of lopinavir/ritonavir has been associated with an increased risk of gastrointestinal adverse events and it has not proven to be effective. No significant differences were observed between patients treated with ribavirin or umifenovir and their respective control groups; Conclusions: Remdesivir and favipiravir are well tolerated and effective in accelerating clinical improvement. This systematic review does not support the use of lopinavir/ritonavir, ribavirin and umifenovir in hospitalized patients with COVID-19.