Not all supplements are created equal. The form of a nutrient can dramatically affect how much your body absorbs, how well it's tolerated, and whether it delivers real results. This evidence-based guide compares chelated, bisglycinate, citrate, oxide, and other common supplement forms, explaining which work best for magnesium, calcium, iron, and zinc. Learn how to choose the right form for your age, health goals, digestive needs, and life stage.