I can confirm that a strict fruitarian diet can certainly lead to low
protein levels... as a strict fruitarian for a number of years (2 - 3 I estimate, but actually 5 if i count the time i ate minimal amounts of salad materials as well...), I had blood tests done at the end of this time and indeed my
protein levels
were low... Total
protein was at 6.5 when the
ideal is supposedly 7.5... And apart from this, my sports performance as judged by my teachers,
was suffering (though I did not feel this in my own body — I
was used to performing at that level and felt it as normal for me... and i
was newer to the sport
than a lot of them... i had great, better
than most endurance... which
was very satisfying... but apparently I just did not have the physical strength that others with
less endurance may have had...) something which immediately improved as I added more
protein to my diet....