Vitamin D is a fat-soluble vitamin that is naturally produced by your skin when you're exposed to sunlight. It's also found in foods like fish and eggs, with some brands of milk fortified with vitamin D.
This nutrient is essential for many functions in the body, including bone health and blood pressure control. It helps your muscles move, prevents inflammation, and aids in cell growth and repair. But vitamin D has an important role in gut health as well—and that can be especially important for those who are overweight or obese, or have diabetes.