I tend to stay away from that stuff and besides if it isnt standarized its a gamble.
I use L Arginine
Omega 3 from alaskan salmon, not a mixture of mackeral, anchovie, etc
Garlic pills
B complex
I dont touch soda til the weekend and try not to drink more than 3 cans on sat and 3 on sun...and I dont mess with diet junk fake sugar. I drink plenty of water and try to watch my diet.
As a result, I have a very high libido and stiff erections. Most times changing a diet can help ED. I never had ED but notcied softer erections about a year ago..dropping some weight helped that.
Even tho I am currently refusing to have sex with my wife as we are separated, I keep taking the stuff cuz its good for me and arginine needs to build up in order for the NO to be effective.
I just masturbate more often.
I tried viagra once for kicks and hated the feeling of the flushed pressure in my face and head.