My friend is freaking anxious. To preface this I want to explain that before I met him I was of the opinion that anxiety was just general nervousness, I'm still under the belief that a lot of people are claiming they have anxiety when they don't. 

The more I've gotten to know my friend the more I've started to notice his anxiety. He won't initiate conversations with strangers, and by that I mean stuff that's seems basic for me like asking for help at the store. Dude always like triple checks minor social details with me, so like "are you sure this is good", "how do you want this basic task done" etc. He's constantly overthinking every social interaction. No matter how much I assure him I am a safe person and that he can say the dumbest shit and I genuinely won't even think about it. When he's talking unless he is given full attention he will start to trail off and only continue when I or someone says I'm still listening. 

I love this guy, I consider him one of my best friends and I hate to see him overthinking these situations. Is there anything I can do other than assuring him that he doesn't need to overthink anything around me at least.