Protein is definitely the building block for growing and repairing tissue, but there is no muscle in your cock.
This is not true.
Veins and arteries have muscular layers, smooth muscles. This may be an interesting subject for research. What does one eat to improve smooth muscle health.
The penis is loaded with veins and arteries. Grow fatter veins and arteries grow a bigger penis. How does one do this? Lifting weights and doing cardio exercise. A protein, good fat rich diet would help.
Speak softly carry a big dick, I'm mean stick!