Zilch; there should be no controversy about this at all, but since the Millerite movement in the 19th century Adventists have embraced an unusual theology around diets. Read the history of Graham’s Crackers or J.W. Kellog for more details. Later, my understanding is much of this was doctrinally formalized by Ellen White. A friend of mine who grew up SDA with a Catholic mother was mistreated at Adventist elementary school because she would pack meat in his lunches, by one of the teachers, and this was recent, I reckon it would have been in the early 90s, I would guess 89-95 or thereabouts. His father had a change of religious perspective and joined the UCC, and his son became a liberal Christian of the sort that are frequently encountered in the UCC, which is how I met him, but he was a decent guy and my theological traditionalism did not preclude a friendship. He told me he is glad his father left when he did, because the Adventists have a system of boarding schools called “academies” for middle school aged children.