Vitamin D is a fat-soluble nutrient important for bone health, enabling calcium and phosphorus absorption. It also supports immune function. Many individuals seek reliable sources of this essential nutrient.
The Two Forms of Vitamin D
Vitamin D exists in two primary forms: Vitamin D2, known as ergocalciferol, and Vitamin D3, known as cholecalciferol. Vitamin D2 is derived from plant sources, including yeast, while Vitamin D3 is primarily produced in animal skin when exposed to ultraviolet (UV) light, or found in animal products like fatty fish and egg yolks. The body can utilize both forms, but Vitamin D3 is generally considered more effective at raising and maintaining Vitamin D levels in humans. Most common plants do not naturally produce significant amounts of either form, especially Vitamin D3.
Naturally Occurring Vitamin D in Plants
While most plants do not naturally contain significant Vitamin D, certain mushrooms are a notable exception. These fungi contain a compound called ergosterol, which can be converted into Vitamin D2 when exposed to ultraviolet (UV) light. This process is similar to how human skin produces Vitamin D3 from cholesterol under sun exposure. The amount of Vitamin D2 produced varies depending on the mushroom type and the intensity and duration of UV exposure.
Specific varieties like shiitake, maitake, and portobello mushrooms can develop nutritionally relevant amounts of Vitamin D2 after being exposed to UV light. UV-treated portobello mushrooms, for instance, can contain significantly more Vitamin D2 compared to untreated ones. Wild mushrooms such as morels and chanterelles, naturally exposed to sunlight, also tend to have higher Vitamin D2 levels. This makes UV-treated mushrooms an important natural plant-based source of Vitamin D.
Plant-Based Dietary Sources
For plant-based diets, fortified foods are a common Vitamin D source. Many plant-based milk alternatives (almond, soy, oat), cereals, and some orange juices are fortified with Vitamin D (D2 or vegan D3). Always check nutrition labels for added Vitamin D content.
Beyond fortified foods, plant-based Vitamin D supplements are another effective option. Vegan Vitamin D3 supplements are available, often derived from lichen, a plant-like organism. These lichen-sourced supplements provide D3 without animal byproducts, making them suitable for vegan diets. While not a plant source, sensible sunlight exposure remains a primary way for humans to produce Vitamin D. Even for those on a plant-based diet, spending a short time outdoors can contribute to Vitamin D levels, though factors like skin tone and latitude influence production.