Sumain Nutritional Supplement (SNS) is a processed composite flour of groundnut, soya bean, guinea corn, and maize grains, and substituted at 0, 25, 50, 75, and 100% diet levels of a Commercial feed. In vitro toxicity study was conducted using Brine shrimp larvae, while in vivo performance of these diets was assessed using wistar albino rats in a 21-day feeding period. Mean body weight difference was measured. Liver extracts were assayed for alanine, and aspartate amino transaminase (ALT, AST) concentrations. Plasma extracts were assayed for haematological, and lipid profiles using standard methodologies. Results showed that SNS extract was safer than a reference tannic acid by 83%, with LC50 of 550. Compared with AST/ALT ratio of 1.17 for 100% Commercial feed, those of SNS-incorporated feeds ranged from 0.92 to 1.16, indicating no apparent damage to liver tissue. At all levels of SNS substitutions, WBC and PCV concentrations were within standard acceptable ranges, while results of MCV and Hb-related parameters exhibited very good biochemical indices of health status during the period of study. 100% and 75% SNS substituted diets particularly, showed potential to reverse thrombocytopenia. Increased Triglyceride (TG) level coupled with lowered levels of Cholesterol (LDL and TC), led to the recommendation of these two SNS diets as good nutraceuticals for human subjects having symptoms of malnutrition.