To investigate the synergistic and combined effects of a seed-vegetable combination, oilseed crops (safflower seed, evening primrose seed, and sesame seed) and cereals (whole buckwheat grain) were extracted with carrot using a low-speed juice extractor. Nutrient composition showed that the mixed seeds juice provided a well-balanced diet to supplement nutrient deficiency. Four assays of antioxidant activities showed that all seed juices exhibited higher activities than carrot juice. Similarly, mixed seeds juice displayed the highest α-amylase and protease activities, implicating the formulation in the improvement of the relatively low digestibility of seed. These results indicated that juice extraction significantly (<0.001) influenced the nutrient contents, antioxidant activities, and digestion enzyme activities of seed juice. The synergistic and combined interactions of seeds and vegetables may be beneficial in enhancing biological functions and result in a well-balanced diet.