This answer suggests that a diet consisting only of fruits is likely to lack sufficient thiamine (B1), niacin (B3) and B12.
What kind of diet can you follow to cover those losses? Would eating grains and nuts be enough?
There are no reliable plant sources of B12 and it must be supplemented.
Eating a range of nuts and seeds should normally cover B1 and B3 requirements. These vitamins are not a concern in typical vegan diets as they are provided by nuts, grains and legumes
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