One of the most important vitamins in winter is vitamin D. However, and precisely in winter, the sun is often a hidden asset. The reduction of solar hours and the increase of cloudy, foggy or rainy days make it a scarce and valuable asset.
It is therefore a key vitamin. Spending at least 30 minutes in the sun with proper protection is one way to achieve this. Some foods such as eggs contain vitamin D, although in a reduced amount.