Is this carbohydrate and protein supplements given for muscle gain really toxic to the body?

Not toxic. Protein and carbohydrate supplements are not toxic to the body, but taking supplements makes it easier on overdo it with your intake. If you exercise, keep your protein intake at no more than one gram per pound of body weight.
Protein sups R OK. . ..If not excessive. Carbs give u energy stores. Each can b damaging if overdone. 2 much of either can b damaging, ; more so with age, ; renal function. Enough is good 2 more is not better. This includes ur total from all sources, foods ; supplements. Also vary each day depending on ur exercise if u have any doubt b cleared by a physician. .