Allium sativum and mental health: A scoping review

Emerging evidence suggests that dietary patterns can impact the development and progression of mental illnesses. Garlic is a commonly used culinary herb and traditional medicine that has been well studied for the treatment of many conditions; less is known about its impact on mental health outcomes. We conducted a scoping review of studies assessing the impact of supplementation of garlic, or one of its constituents, on mental health symptoms. Eligible studies included human experimental and observational studies and animal studies. Thirty-one studies met criteria including nine human experimental studies, three human observational studies, and 19 animal studies. Eight of nine small human experimental studies reported positive signals of an effect on mental health outcomes; however, several used garlic in combination with other natural health products. The results of the human observational studies were mixed. Most of the 19 animal studies reported mechanisms by which garlic supplementation impacts mental health and all reported improved anxiety-, depression- and addiction-like behaviours. Discussion : Preliminary evidence suggests that garlic supplementation may improve mental health outcomes; however, these findings are limited by a small number of human experimental studies, small sample sizes, and methodological heterogeneity. There is a need for further randomized controlled trials to assess the impact of garlic on mental health outcomes. • This scoping review sought to identify and map the current clinical and mechanistic research on garlic and its impact on mental health. • Nine human experimental studies, three observational studies and 19 animal studies assessed the impact of garlic on a mental health outcome. • Most of the human studies reported a benefit; however, several used garlic in combination with other natural health products • The animal studies reported mechanisms such as reduction of inflammation, oxidative stress, modulation of neurotransmitter pathways and modulation of the gut-brain axis.