Uh, no, chances are not that. Unless you are very stupid (and I don't think he is....) you can get what you need with just about any diet.

Replace that with "Unless you are reasonably smart (and I think he is) you don't get what you need with certain diets."

The issue with vegetarianism is that humans are not meant to eat just vegetables. Therefore, great care must be taken to get certain nutrients which are not found often in vegetables. Protein is the big one, but there are others.

However, with a properly crafted diet (an issue that most? vegetarians run into) you should be able to get everything. (possibly with the aid of supplements).

Yeah. Have you ever seen the food schedule for someone who beat cancer? Surf and Turf. Steak and Potatoes. Salmon and Chicken. 4 or 5 meals a day once your appetite comes back.

Cancer treatments typically deplete the body of protein and lean tissue, and most doctors agree that eating meat is just the fastest/easiest way to recover.

Its possible/probable a macrobiotic diet could contain enough protein and still be 100% vegan, but if there's another "imbalance" (say GMO Soy or Legumes which contain Estrogen) that could create issues he's had to deal with during his recovery.

When I was in the UK I tried out "quorn" - I think that was how you spelled it. Basically a fungal/mushroom grown substance that is high in protein. All the vegoes I knew loved it (actually it tasted good to me), that and lots of beans/legumes.

I really don't enjoy eating meat - so once I tried vegetarianism for about 4 months. I have never been so sick in my life ! It probably was co-incidence, or could have been lack of some nutrients (or body adjusting) but it was horrible.