The present study evaluated the prophylactic and safety of Ocimum sanctum. Linn leaf juice in diabetes mellitus, infectious pneumonia and heat stroke among adult inhabitants of East and West Midnapur in West Bengal. Three hundred participants with age in the range of 45-60 years and comorbidity-free people were recruited and divided into three groups: the experimental (n=100), the safety (n=100), and the control (n=100). Experimental group was orally administered Tulsi leaf juice once daily and 28 days continuously at 5 g/kg body weight with an empty stomach during winter and summer seasons. The safety group individual was monitored on side-effects, weight variation, and changes in appetite. Telephonic and direct follow-up was done in terms of clinical outcomes in terms of the incidence of the disease being targeted, and related symptoms. Statistical testing of the analysis revealed that Tulsi leaf juice was tolerated with no side effects or changes in appetite and body weight. Significantly, none of the experimental subjects had diabetes, pneumonia, or heat stroke, whereas the control group had a cumulative disease incidence of 16%. Comparative seasonal surveys revealed consistent prophylactic efficacy, and clinical monitoring of complete absence of symptoms in the experimental group. These results indicate that daily intake of Ocimum sanctum. Linn leaf juice is safe, non-toxic, and effective as prophylactic therapy against metabolic, respiratory, and heat-associated health hazards in normal healthy adults