It can be naturally found in mushrooms, algae, fruits, and veggies
Additionally, consuming other foods like Brussels sprouts, cauliflower, and kale can also provide the three key building blocks (glutamate, cysteine, and glycine) to manufacture glutathione naturally
Fortunately, glutathione injections do not cause weight gain
You can achieve the same result with generic bottles from your medicine cabinet
I will say, despite the fact that the cispeptin pathway is well known, and despite the fact that the cispeptin peptide is designed to mimic a naturally occurring peptide that has a pretty constrained set of functions, in the hypothalamic pituitary system
However, p21 activates Rb to produce a bioactive secretome that places stressed cells under immunosurveillance