What is your opinion on taking cutrilline as a natrual supplement for ed in other wise healthy men above 40?

Malarkey! Citrulline: Any purported benefits are profit-driven only and false advertising. More amino acids may in fact be bad, since the evidence shows that high protein diets are causing increased death and disease. Save your money. Reverse plaque build-up (which effects circulation everywhere in body, inc. penis) with a 10% fat diet. See http://www.med.nyu.edu/content?ChunkIID=104664 and try Dean Ornish's diet.