This is another very important vitamin that everyone should be mindful of. Sunshine is a great natural form of Vitamin D, and even fair-skinned people should try to get a few minutes of sunshine a day on bare skin. There is no need to risk skin cancer—just a few minutes of mild sun on your arms or hands is a helpful way to obtain a natural source of Vitamin D. If you are very fair-skinned then you can do so when the sun is mild, such as in the mornings and late afternoons. Vitamin D deficiency is becoming a worldwide concern. Some people are getting what would be considered adequate amounts of sunlight, and yet are unable to synthesize it. It is important that people have their Vitamin D blood levels taken yearly to see if they have adequate levels in their blood. According to many medical journals, inadequate levels of Vitamin D can lead to many serious illnesses like Diabetes Type 2, breast cancer, colon cancer and so on. , therefore you may also choose to consume a dietary supplement, especially if you are someone who is suffering from low Vitamin D levels. The vegan source of dietary Vitamin D is D2 (ergocalciferol), usually synthetic or manufactured from yeast. It can be obtained in a tablet form, or found in supplemented foods such as some soy milks. Please note vitamin D3 normally is NOT vegan, however there are a few D3 vegan supplements available. It is important that one do research as there are a few products which claim to be vegan D3, but they are not. There are two supplements which I am aware of which claim they are vegan D3 1) Vitashine 2) Source of Life Garden D3. Both products have been researched and the production process and the product itself contain no animal products.
I would recommend scheduling a 25(OH)D (25-hydroxyvitamin D) blood test.
Please see this link from NutritionFacts.org which has a number of videos relating to Vitamin D deficiency. (Disclaimer: Please note I do not endorse opinions, links or ads on NutritionFacts.org)