I take fish oil and vitamin D. I only ever take vitamins if I think I'm not getting enough of the certain thing in my diet, which in general is pretty good! My go-to source is this where I used to purchase the vitamin.
I don't know if I speak for everyone but I feel that this bizarre taboo of penis size in our culture has cultivated a rampant stampede of misinformation. Admittedly I'm not the most experienced with measurements or with penises but if I was to see this guy dick without measuring I would have...