The Hard Truth About Peptides for Muscle Growth (Spoiler: They Don't) RP Strength There's a lot of confusion around peptides and muscle. Here's how I actually think about it. Most peptides don't build muscle directly. They improve the systems that allow muscle to grow. First, Peptides: performance boosting, anti ageing drugs or dangerous snake oil? Amazon.com: NOW Foods Supplements, Glutathione 500 mg, With Milk Thistle Extract & Alpha Lipoic Acid, Free Radical Neutralizer*, 60 Veg Capsules : Health & Household