It sucks when you eat right but still end up with an iron deficiency. Or what about being a gastric bypass patient and needing vitamin B12 shots for the rest of your Surgery is a powerful tool but it's not the whole plan. After bariatric surgery, your body absorbs supplements differently. Deficiencies in B12, Vitamin D, Iron, and Zinc are common but B12 Injections: How They Work and Who Needs Them Meo Nutrition Different phases of diet to be followed after Gastric Sleeve Surgery