All natural. I said it before but I will repeat it. He was muscular at 15 and there are pictures to prove it. He was muscular during World War II when he served in a remote area and the only thing he had was a 100lbs barbell he repped out with. His nick name during the war was the Shape. He was built decade after decade. Until his health failed him in his later years he was in shape.
The nonsense I hear repeated about the phony conversations concerning his use I see repeated on various boards is no proof. The first anabolic steroid made was dianabol. He was finished competing 9 years before it was invented. Bodybuilding back then was a really small subculture of a sport.