I know there is such thing as gut permeability where you aren't properly absorbing the right vitamins and minerals into their intended places. I know that indigestion, lactose intolerance, stress, low/high stomach acids, gluten intolerance can destroy the micro villi in the small intestine making for malabsorbtion. That is why there are some people who eat certain amounts of nutrients but they still show up as deficient on their lab results for said nutrients.
"If man made it, don't eat it" - Jack Lallane
People say I am on a "crazy" diet. What is so crazy about eating veggies, fruits, seafood and organ meats? Just because I don't eat whole wheat and processed food doesn't make my diet "crazy". Maybe everyone else with a SAD are the "crazy" ones for putting that junk in their system.