Research was conducted with the aim of determining the nutritional value of wheatgrass juice as a natural food supplement. Genetic specificity in the content of biologically active components in wheatgrass juice was tested on 100 varieties of wheat of Eurasian breeding origin and 5 wild relatives. These varieties were grown in a climate chamber. Based on the obtained data, 9 varieties were selected, on which the impact of biofortification of wheat with selenium and zinc was tested in a field experiment and on the content of biologically active components in the juice. Special emphasis is placed on the influence of ecological growth conditions on antioxidant activity and the content of nutritionally valuable phytochemicals in wheatgrass juice. The content of chloroplast pigments, phenols, flavonoids, flavanols, phenolic acids, vitamin C, proline and malondialdehyde was determined in the samples collected from the set of experiments. Total antioxidant activity in wheatgrass juice was determined using DPPH, FRAP and ORAC methods, and Fe ion chelating capacity was determined. The results indicate a significant influence of genotype and ecological conditions of cultivation on the nutritional quality of wheatgrass juice. Also, it was determined that ecological conditions beyond the optimum for wheatgrass grown in controlled conditions, related to the reduction of the amount of accessible water, lower intensity of lighting and lower temperatures, increase the nutritional quality of wheatgrass juice through the stimulation of synthesis and the accumulation of products of secondary metabolism. Also, biofortification with Se and Zn had a negative effect on the content of vitamin C and flavonoids. These are important components of the plant's antioxidant status, however in some cultivars this negative influence was significantly less pronounced. Knowing the specificity of cultivars and the physiological response of wheatgrass to different growing conditions, allows us to select varieties where it is possible to increase the concentration and bioavailability of Se and Zn through agronomic biofortification, without negatively affecting the important components of the nutritional quality of wheatgrass juice.