What is vitamin D derived from? The essential sources

January 14, 2026 •

3 min read

An estimated one billion people worldwide have insufficient vitamin D levels. This essential nutrient, often called the "sunshine vitamin," is primarily derived from three sources: sunlight exposure, certain foods, and dietary supplements. Understanding where to obtain vitamin D is crucial for maintaining overall health, particularly bone density and immune function.

Quick Summary

Vitamin D is obtained through three primary channels: the skin's synthesis using sunlight, dietary intake from certain natural and fortified foods, and supplements. The two main forms, D2 and D3, come from different sources, with the sun and some animal products providing D3, while D2 comes from plants and fungi. Supplements also offer a reliable source for those with limited sun exposure or dietary options.

Key Points

Sunlight is the primary source: The skin naturally synthesizes vitamin D3 from a cholesterol precursor when exposed to UVB rays from the sun.
Dietary sources include animal and fortified foods: Fatty fish, eggs, and liver are natural sources, while milk, cereals, and juices are often fortified.
Two main forms exist: D2 and D3: D2 (ergocalciferol) comes from plants like mushrooms, while D3 (cholecalciferol) is from animal sources or lichen.
Supplements offer a reliable alternative: For those with limited sun exposure, darker skin, or dietary restrictions, supplements are a safe and effective way to get enough vitamin D.
Bioavailability differences: Vitamin D3 from supplements may be more effective than D2 at raising blood levels, although both are useful.
Risk of skin cancer from sun exposure: While sunlight is a natural source, prolonged, unprotected exposure increases skin cancer risk, making other sources important.

The Primary Source: Sunlight Exposure

The most significant source of vitamin D for many is sunlight. When the skin is exposed to the sun's ultraviolet B (UVB) rays, a natural process converts a cholesterol derivative into vitamin D3. Several factors influence how much vitamin D your body can produce from the sun, including time of day, season, location, and skin tone. Darker skin, with more melanin, produces less vitamin D from sunlight. While the body regulates production to avoid toxicity from the sun, the risk of skin cancer leads many health professionals to recommend other sources.

Dietary Sources: Natural and Fortified Foods

Few foods naturally contain high levels of vitamin D, and these are mainly animal-based. Fortified foods and supplements are often necessary, particularly when sun exposure is limited.

Naturally rich sources: Fatty fish like salmon and tuna, along with cod liver oil, are excellent sources of vitamin D3. Beef liver and egg yolks contain smaller amounts.
Mushrooms: UV-exposed mushrooms provide vitamin D, primarily D2, making them a plant-based option.
Fortified foods: Milk, some plant-based milks, cereals, orange juice, and yogurt are often fortified with vitamin D.

The Role of Dietary Supplements

Supplements are a reliable option for many to ensure adequate vitamin D intake, especially for those with insufficient sun exposure or dietary limitations. Supplements contain either vitamin D2 or D3.

Vitamin D2 (Ergocalciferol): Derived from UV-irradiated yeast and plants.
Vitamin D3 (Cholecalciferol): Typically sourced from lanolin (from sheep's wool) or lichen for vegan options.

Studies suggest D3 might be more effective at increasing blood vitamin D levels than D2, though both are absorbed well.

Comparison of Vitamin D Sources


Feature	Sunlight	Food Sources	Supplements
Form of Vitamin D	Primarily D3	Natural: D3 (animal), D2 (some mushrooms). Fortified: D2 or D3.	D2 or D3.
Dependence on location/season	High. Reduced in winter/higher latitudes.	Low. Fortified foods available year-round.	Low. Consistently available.
Associated health risk	Sunburn, skin cancer risk with prolonged exposure.	None from normal intake.	Low risk of toxicity from excessive intake.
Reliability	Variable.	Variable. Fortified levels can differ.	High. Consistent, measured dose.
Natural or Manufactured	Natural (body's synthesis)	Natural and Fortified	Manufactured

Conclusion: A Multi-faceted Approach

To summarize, vitamin D comes from multiple sources. A combination of safe sun exposure, a diet including vitamin D-rich and fortified foods, and potentially supplements is often the best strategy. Individuals with certain health conditions, darker skin, or limited sun exposure may need to prioritize supplementation and should consult a healthcare provider. While our bodies can produce vitamin D from the sun, integrating various sources is effective for maintaining adequate levels.

More detailed information on vitamin D dietary needs can be found at the National Institutes of Health website.

Considerations for Specific Groups

Some groups need to be particularly mindful of their vitamin D intake:

Infants: Breastfed infants often require vitamin D supplements.
Older Adults: Reduced skin synthesis with age makes supplements important.
Vegans/Vegetarians: Animal-based natural sources are not an option, so fortified foods or plant-based supplements (like from lichen) are crucial.
Dark-skinned individuals: Higher melanin reduces sun-induced production; supplements are frequently recommended.
People with medical conditions: Conditions affecting fat absorption or liver/kidney function may impair vitamin D processing, often requiring monitored, higher-dose supplements.

Frequently Asked Questions

The primary natural source of vitamin D for most people is exposure to sunlight. The skin produces vitamin D3 when exposed to the sun's UVB rays.

No, they are not the same. Vitamin D2 (ergocalciferol) is derived from plants and yeast, while vitamin D3 (cholecalciferol) is produced in the skin of animals (including humans) and found in animal products and some lichen.

It is difficult for most people to get sufficient vitamin D from naturally occurring food sources alone, as few foods contain it. This is why many foods are fortified.

Yes, many foods are fortified with vitamin D. Common examples include milk, certain cereals, orange juice, and some plant-based milks.

Food sources rich in vitamin D include fatty fish (like salmon, tuna, and mackerel), fish liver oils, beef liver, egg yolks, and UV-light-exposed mushrooms.

No, the body has a self-regulating mechanism that prevents vitamin D toxicity from sun exposure. However, excessive sun exposure is harmful due to the risk of sunburn and skin cancer.

Vegan vitamin D3 supplements are typically sourced from lichen, a symbiotic organism containing a fungus and alga. This offers a plant-based alternative to the traditional lanolin-based D3.