vitamin d

You might think you get adequate Vitamin D from the sun. But you may not, and deficiency of the nutrient can contribute to stress injuries.

Sometimes the sun won't cut it. This key nutrient plays a role in your muscles, mood, and energy levels—meaning a deficiency can impact your health in a number of ways.

Today on "Ask the RDN:" How can runners know best whether they're getting enough key nutrients, such as salt and Vitamin D?