According to Aaron Spitz, MD and Chief representative for America's urologists to the American Medical Association, "eating natural produce - vegetables, fruits, and whole grains - plays defense for your penis" It turns out that if you eat a lot of green leafy vegetables or other polyphenol-rich food along with simple carbs or high-fat, animal-based foods, there is a protective effect, and fewer toxins and free radicals are unleashed on your blood vessels and tissues"

According to him, its good to take a 90/10 approach. Keeping meals about 90 percent unprocessed and plant based and the 10 percent the "bad" stuff if you must.

Reference:

Aaron Spitz, 20 Feb, 2018, The Penis Book: A Doctor's Complete Guide to the Penis--From Size to Function and Everything in Between, Rodale Books.