Testosterone can be risky, cause hair loss or even gyno. Problem with testosterone is it can convert to estrogen easily especially if you already have high cortisol or estrogen.
And serotonin can cause issues down there too, hence the anti depressants causing issues.
Dietary cholesterol, saturated fat, even carbs to some extent, actually help with boners. Red meat, dairy fat, butter, etc.
Its the omega 3/omega 6 oils that can hurt, and omega 6 more so than omega 3. So that basically includes all fried foods, chips, rice, fish, most nuts and most seeds and most oils… even most desserts unless theyre made using butter or olive/avocado/coconut oil or creme.
Pork fat and chicken fat is a nono because they usually have way too much omega 6 also.
What is your diet like? What supplements/drugs/medicines do you use? Most of the time those things have side effects.
Its about blood flow, but also hormones, and also muscle. The dick is a muscle, so generally things that improve muscle growth or blood flow, should also improve it. That means to some extent, you need carbs/protein in the diet. So if youre doing a keto diet where protein/carbs are too low that could easily hurt things.