Just my two cents, I have been vegan for over 2 two years. I first got hppd around 2 and a half years ago. I can say that it has made very little difference to my HPPD (as I have had it almost as long as I have been vegan). But in terms of health separate of HPPD I feel a hell of a lot better. And I look younger, my skin and complexion is lovely, lost a lot of weight (was over weight before) and I have a lot more natural energy, unless I eat junk food like chips . Can't say it helps with anxiety, at least for me, as I had terrible anxiety and even paranoia whilst being vegan and having hellish HPPD. Valerian root helped me with that though, and I do think valerian helps with my HPPD. However, I noticed a dramatic improvement with my HPPD a few weeks back whilst on holiday from university. I thought that perhaps the super food smoothies my Dad makes could have attributed to that, the smoothies are full of loads of fresh fruit, spinach, goji berries and more (I wasn't necessarily less stressed as I had a ridiculous amount of work to do, so less stress wouldn't really be it) but I have also incorporated 45 minutes of self reiki into my daily meditation schedule. So depending on what you believe in, this could have helped Sorry if this lets some of you guys down, but I've had a lot of experience here. But in terms of diet, cut out anything with sugar in ( people may already know this) but I know if I start drinking sugary drinks or eating sweets my HPPD is made a lot worse! The same as when I drink caffeine. Oh and process foods, that stuff f***s me.