You are overweight or obese, or have more muscle mass. If you are overweight or obese, your body requires more vitamin D compared to a thin person with less body fat. This is also true for people who weigh more as a result of having a higher amount of muscle mass.

You have gastrointestinal issues. Having gastrointestinal conditions that occur in the gut like Crohn’s disease, celiac and non-celiac gluten sensitivity, and inflammatory bowel disease may be sign you are not getting enough vitamin D.

Your mood is down. The amount of serotonin your body produces is linked to the amount of sun exposure you get. Our body produces more serotonin when we are more sun exposure, and produces less serotonin when we get less sun exposure.

You are aged 50 or older. As we age, our skin does not make as much vitamin D as a result of sun exposure. The kidneys are also less capable of converting vitamin D into the form that is used by our bodies. When we get older, we tend to spend more time inside due to certain health conditions or the inability to be as physically active and therefore, we get even less sun exposure and less vitamin D.

You have dark skin. African Americans are at higher risk of being vitamin D deficient because they have more melanin in their skin. Having more melanin decreases the skin’s ability to make vitamin D from sun exposure.

You have bone pain. Bone pain is a sign of vitamin D deficiency osteomalacia. This is different than the type of vitamin D deficiency that causes osteoporosis in adults in that the vitamin D deficiency is limiting the ability to put calcium into the collagen matrix in the bones, which can result in aches and pain in the bones.