A quick way to increase your vitamin D intake is to get more unfiltered, unprotected sunlight every day (see below for more information). However, if you live in a place where the sun doesn't shine all year round, or do a job where you have to spend a lot of time indoors, this can be a challenge. In this case, you may need to add. I suggest choosing a vitamin D3 supplement and working closely with your doctor to monitor your levels.
Some foods also contain vitamin D, such as shiitake and button mushrooms (leave mushrooms in the sun to increase their vitamin D levels), mackerel, sockeye salmon, cod liver oil, sardines, and eggs, but you probably won't consume them in high enough amounts to meet all of your nutritional needs.