During winter there is increase risk of vitamin d deficiency and infections. We need vitamin D to maintain our health and to fight infections. And being winter, when people need vitamin D the most, most of us aren't getting enough of it. These are the months that we are exposed to more infections because we spend less time outdoors and more time inside.
In the winter months, you should increase your vitamin D intake by consuming foods that are rich in vitamin D like fatty fish (salmon, tuna, anchovies), mushrooms, eggs and cheese) and take your vitamin D supplements.
Winter is also a good time to check your vitamin d levels.