This guy must be crackers, sorry, I had to do it.
This story rates low on my believability meter.
Years with only crackers and tea, heck, that is what the British sailors woudl eat. A diet of hardtack and grog, or whatever nutritionless swill they put down, led to scurvy, beri beri, rickets, gonorrhea - OK, perhaps not gonorrhea, but the tars had to explain it to their wives somehow.
It was the hardtack dear, trust me.
Nah, this guy looks too healthy to me to have been bereft of anything with vitamins for so many years.
I vote balderdash, if I spelled it right.
Before criticizing a person, walk a mile in his shoes - then you are a mile away and you have his shoes!