No, it cannot. The product is described as a supplement, which means it is meant to add to a diet, not replace food. Protein-rich foods such as meat, fish, eggs, dairy, legumes, nuts and seeds provide many nutrients at once, including a range of amino acids. A capsule with only L-lysine does not offer that variety.
L-lysine is one essential amino acid, but the body needs several amino acids for protein assembly. People who follow restrictive menus or eat little protein-rich food may use this product to add a measured amount of L-lysine, but their overall eating pattern still has to supply the rest. A dietitian or doctor is the right person to assess whether a single amino acid supplement is appropriate for a specific restrictive diet.
This product is not intended to diagnose, treat or prevent any disease, and it should not be used as a substitute for professional dietary advice. If you have any doubts about whether you are getting enough lysine from food, a qualified professional can help you evaluate your usual intake and decide whether a supplement is needed.