4. Vitamin D
This vitamin isn’t just needed for healthy skin and hair. Vitamin D is also needed for a healthy and functioning immune system. Without enough vitamin D, the body is prone to weakness and disease. To get enough of this vitamin, spend around 10-20 minutes in sunlight, as the body can make its own vitamin D in the presence of sunlight. If you are unable to do so, add some Vitamin D supplements to your diet.