Which vitamins do most people actually lack daily?

Most people are commonly deficient in vitamin D, since it requires sun exposure to produce and many people work indoors or live in northern latitudes. Studies consistently show a large portion of the global population has insufficient levels. Magnesium is technically a mineral but is widely under-consumed. Vitamin B12 is another common shortfall, especially in vegetarians, vegans, and older adults who absorb it less efficiently. Vitamin K2 is often overlooked and genuinely lacking in Western diets. Folate and iron deficiencies are particularly common in women of reproductive age. Vitamin A deficiency is more of a concern in developing countries. Most other vitamins are generally adequate if someone eats a reasonably varied diet.