Vitamin D is the sunshine vitamin and is most commonly associated with mood and happiness. It’s produced when your skin is exposed to sunlight on a regular basis, and a deficiency in vitamin D can lead to weak bones, depression, mood swings, rickets, cardiovascular problems, and many more issues. Although our bodies can produce vitamin D naturally, direct exposure to sunlight on a daily basis is required to initiate the natural production process, something many people don’t get enough of. The best food sources for vitamin D are fatty fish, egg yolks, foods fortified with added vitamin D, or a supplement. If you are going to take a vitamin D supplement, be sure to check with your doctor first to figure out the right dosage for you as it’s a fat-soluble vitamin that can accumulate in your system if you take more than your body can process.