First of all I have high suspicions of this website being more on the end of fake alternative medicines that individuals are going to try to sell you. Western medicine isn't the best in preventative care since they don't emphasize diet enough. But when your doctor is telling you now that you have to stick with plant-based diet, that's most definitely what you need to do. You're risking you life otherwise. He has motives to perhaps over-prescribe you pills, but not food. This is just so you're not risking your life, and consequently that he doesn't get sued for malpractice when you die.
The original post is nothing to worry about. Idiots will go vegan and do it wrong all the time. We call them junk food vegans. Raw veganism can also be dangerous for children due to the caloric density being too low low (they can't fit enough food in their stomachs to get enough nutrients). You also need to be supplementing B12 (best is just a multivitamin pill such as the centrum chewables I have right here). What you want is the plant based diet your doctor recommends--cooked starches, veggies, fruits, nuts, and bread. This is what the credible plant based doctors that aren't trying to sell you their special idea will all tell you. This is how they improve their lifespan decades beyond average. Again, do not cheat--you're risking your life.
If you have any questions, please find me on facebook and ASK. Just search my name in facebook and I'll pop up right away (Corvallis, OR).