Our bodies create vitamin D when exposed to the sun. Still, vitamin D deficiencies are extremely common. Some are more likely to develop a deficiency than others, which requires supplementation, including people who live in cold or dark areas that don't get much sunlight, older adults, pregnant people or people with darker skin tones. Pigmentation can block sunlight absorption. Because of this, Americans of color have a deficiency rate of 70%. Read more: Vitamin D Is Crucial for Immune Health -- Make Sure You're Getting Enough Common symptoms of vitamin D deficiencies: Fatigue or weakness Muscle or bone pain Muscle twitching  Stiff joints Increased instances of falls and fractures