Vitamin D Also known as the "sunshine vitamin," has been studied widely for its vast array of health benefits. Over 100 years ago, researchers have also been studying its benefits in immunity, cancer, autoimmune diseases, inflammation, and other chronic illnesses. Vitamin D can be obtained from food, supplements, or skin exposure to the sun. For those people who live in colder climates and don't get much sun exposure, or whose gut doesn't readily absorb the vitamin D in food or supplements, weekly injections are an excellent option for maintaining optimal levels.