A vast number of American adults (93%, to be specific) aren't consuming enough vitamin D daily. Because numerous factors affect the body's ability to synthesize vitamin D in the skin during exposure to sunlight, diet and high-quality supplementation are key to achieving optimal vitamin D status (and even diet isn't the most efficient way to get enough D—more on that later).*
These sun confounding factors include time of day, time of year, location, skin tone, wearing SPF, air pollution, and even age. Combined with the reality of our lives—which are mostly spent indoors, these factors make getting enough D from the sun unrealistic.
When it comes to dietary sources of vitamin D, it's not as simple as eating your vegetables. The only "veggie" (it's really a fungus) that contains the essential nutrient is irradiated mushrooms, which are exposed to UV light to get their vitamin D2 (a significantly less potent form of vitamin D).
Other modest sources of D include a list of animal products (like cod liver oil and eggs) and fortified foods like milk, O.J., and cereal. These are all fine, but the problem comes when you consider how much of those food items you actually need to consume for an optimal dose of 5,000 I.U. or more a day. According to mbg's director of scientific affairs, Ashley Jordan Ferira, Ph.D., RDN, that shakes out to 294 cubes of cheddar cheese or 7 cups of irradiated mushrooms every single day. (Yikes!)
Unless you want to live on cubed cheese for the rest of your life, you might want to opt for an efficacious supplement that can do the trick—like mbg's vitamin D3 potency+, which provides 5,000 I.U. of sustainable D3 derived from organic algae and organic olive, avocado, and flaxseed oils for optimal absorption, all in just one gelcap a day.*