In addition to keeping your peepers in tiptop shape, vitamin A also helps your immune system function at its best and keeps cells growing and developing as they should (and that’s not all, either).* Clearly, there’s a lot that goes on behind the scenes in order for your body to put the various forms of vitamin A you consume to work. When you consume retinol-containing animal foods, for example, the animal basically did one step of the process for you by converting the carotenoids they consumed from plants into that retinol form, notes Drake. And when you consume carotenoids from plants, you gain the unique antioxidant attributes of beta-carotene, which is a phytonutrient (aka, plant nutrient).* Research shows that when there’s inadequate vitamin A, the integrity of this lining is suboptimal, affecting barrier function of the respiratory tract, digestive tract, and eyes against possible invaders or compounds we don’t want to cross these barriers.* This is relevant since 45% of adults fall short4 on the nutrient. Maintaining ample vitamin A intake has, unsurprisingly, been linked with vision support via long-term eye health5.* Its most famous skin-healthy version is actually topical: retinol, a vitamin A derivative. When applied to the epidermis, it promotes skin cell turnover, evenness, smoothness, and vitality6. Furthermore, vitamin A deficiency also affects the immune system. Michels notes that vitamin A deficiency, particularly in children, has been linked to higher susceptibility to outside invaders, like viruses. In fact, partially for this reason, the World Health Organization9 has identified vitamin A deficiency as a notable public health problem in many parts of the world. Green leafy vegetables—think broccoli, kale, spinach, and collards—also contain these carotenoids. However, the large amounts of chlorophyll, which gives these plants their green color, keeps those carotenoids from visibly shining through. The ultimate (i.e., most concentrated) source of vitamin A, though, comes from an animal source—and one you may not be super-stoked to eat: beef liver11. Of course, you can also get your fair share of vitamin A from supplements; most quality multivitamin formulas include it in the mix. Though different supplements may contain different forms of the vitamin, many contain both retinol and beta-carotene8, for synergy reasons and to provide your body with both sources. Also, vitamin A is fat-soluble and thus can store in fat tissue when consumed in very large amounts over time. Toxicity can be a concern with the retinol form (but not beta-carotene). Given that, it is important to be aware of how much preformed vitamin A (aka, retinol) you are ingesting. Specifically, 900 micrograms RAE (retinol activity equivalents) per day for adults is a healthy level to support sufficiency of this essential nutrient. Excess retinol is considered a high dose of 3,000 mcg or above (i.e., the Tolerable Upper Intake Level11). Above this level, especially if you are pregnant13, there can be concerns related to normal development of the fetus.
