John talks about whether agmatine sulfate really increases nitric oxide. Galgano F, et al. Focused review: agmatine in fermented foods. Frontiers in Microbiolgy. 2012 Jun 7;3:199. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3369198/ Gadkari TV, et al. Agmatine induced NO dependent rat mesenteric artery relaxation and its impairment in salt-sensitive hypertension. Nitric Oxide. 2013 Aug 29;35C:65-71 http://www.ncbi.nlm.nih.gov/pubmed/23994446 Sidney M. Morris Jr. Arginine Metabolism: Boundaries of Our Knowledge Journal of Nutrition June 2007 vol. 137 no. 6 http://jn.nutrition.org/content/137/6/1602S.long Link to table of Agmatine content in foodstuffs http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3369198/table/T1/ Piletz JE, et al. Agmatine: clinical applications after 100 years in translation. Drug Discov Today. 2013 Sep;18(17-18):880-93 http://www.ncbi.nlm.nih.gov/pubmed/23769988 Pinthong D, Hussain JF, et al. Comparison of the interaction of agmatine and crude methanolic extracts of bovine lung and brain with alpha 2-adrenoceptor binding sites. British Journal of Pharmacology. 1995 June; 115(4) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1908502/pdf/brjpharm00187-0147.pdf Also here is a nice review of the evidence from a very good site: http://examine.com/supplements/Agmatine/