The study conducted a comprehensive search across various databases for studies published until June 9, 2022, exploring the relationship between carrot intake, α-carotene intake, α-carotene plasma concentration, and cancer incidence. Involving 198 observational studies, the systematic review identified 50 prospective studies (52,000 cases) linking carrot intake (directly or as α-carotene) to a substantial reduction in cancer risk (RR 0.90, 95% CI 0.87–0.94, P < 0.0001). Additionally, 30 prospective studies (91,331 cases) examining plasma α-carotene levels revealed a similarly significant risk reduction (RR 0.80, 95% CI 0.72–0.89, P < 0.0001), with moderate inter-study heterogeneity (I2 = 36% and 26%) and nonsignificant interaction with cancer types.

The findings emphasize the robust association between carrot consumption and decreased cancer risk, urging active encouragement of carrot intake. While α-carotene was used as a marker, the study suggests the need for further investigations into non-carotene-focused hypotheses to understand the underlying mechanisms of this association.