I don't think that a diet like Atkins can start Dupuytren, I never heard of that and I couldn't imagine how. I think the same applies to Vitamin C, no proof for being good or bad. Some people reported good experience with Vitamin E but the results were not reproducible and are not consistent enough for a recommendation.

There are comments in this forum that e.g. eating lots of tomatoes couls possibly slow down the disease. But this is also a single, individual observation, maybe worth trying (if you like tomatoes), but no proven therapy.

Wolfgang