[jimbo2012]

Don't know him but Wikipedi reports

Criticism

Perlmutter's book has received criticism for perceived 'hyperbole' and misrepresentation of data.
Johnson, Nathanael. "Is gluten lobotomizing you?". Grist Magazine. Retrieved 4 February 2014.

Epidemiologist Dr. David Katz, founding director of Yale University's Prevention Research Center, has criticized Grain Brain, saying "Perlmutter is way ahead of any justifiable conclusion" and that many of its claims are "wildly preposterous".