Where does H get vitamin D from?

December 9, 2025 •

3 min read

While sunlight is the primary natural source of vitamin D, its effectiveness can be limited by factors such as latitude, season, and skin tone. Understanding where does H get vitamin D from involves a look at three key avenues: natural synthesis through sun exposure, dietary intake from food, and supplements.

Quick Summary

The human body obtains vitamin D from sunlight exposure, certain foods, fortified products, and supplements. Its production is influenced by factors like geographic location, season, and skin pigmentation, making alternative sources crucial for maintaining sufficient levels.

Key Points

Sunlight is a key source: The skin synthesizes vitamin D3 when exposed to UVB radiation from the sun, but many factors can limit this process, including location, season, and skin pigmentation.
Fatty fish are rich natural sources: Salmon, trout, mackerel, and fish liver oils are among the best natural food sources of vitamin D3.
Fortified foods provide a steady supply: Many common products, such as milk, cereals, and orange juice, are fortified with vitamin D, providing a reliable dietary intake.
Supplements offer precision and safety: For consistent and controlled intake, especially when sun exposure or diet is insufficient, supplements are a recommended option.
Vitamin D requires activation in the body: The vitamin D acquired from sun or food is inactive and must be converted by the liver and kidneys into its active form, calcitriol.
Deficiency risks are widespread: Groups with limited sun exposure, darker skin, and certain health conditions are at higher risk of vitamin D inadequacy and may need supplements.

The 'Sunshine Vitamin' and Skin Synthesis

Our bodies can produce vitamin D when the skin is exposed to ultraviolet B (UVB) radiation from sunlight, converting a cholesterol derivative into vitamin D3. However, the amount of vitamin D produced through sun exposure is influenced by several factors:

Latitude: Less intense sunlight in regions further from the equator limits UVB exposure, especially in winter.
Season and Time of Day: Peak production occurs during summer, typically between 10 a.m. and 4 p.m., when UVB rays are strongest.
Skin Pigmentation: Higher melanin levels in darker skin reduce UVB absorption and vitamin D synthesis.
Other Factors: Sunscreen and clothing can block the necessary UVB rays.

Dietary Sources of Vitamin D

Dietary intake is important, particularly when sun exposure is limited. While few foods naturally contain high amounts of vitamin D, some are notable sources.

Foods Rich in Vitamin D3 (from animal sources)

Fatty Fish: Excellent options include salmon, trout, tuna, and mackerel.
Fish Liver Oils: Cod liver oil is a concentrated source.
Eggs: The yolk contains vitamin D.
Beef Liver: Provides smaller quantities.

Foods Containing Vitamin D2 (from plant sources)

Mushrooms: Varieties exposed to UV light can be a source of vitamin D2. Many commercial mushrooms are treated with UV light to boost their vitamin D content.

Fortified Foods

Many common foods are fortified with vitamin D to help people meet their needs, providing a significant portion of dietary vitamin D in many diets.

Dairy and Plant-Based Milks: Cow's milk and alternatives like soy, almond, and oat milk are often fortified.
Cereals and Spreads: Many breakfast cereals and margarines contain added vitamin D.
Other Products: Some yogurts and orange juices may also be fortified.

Vitamin D Supplements

Supplements are a reliable way to ensure adequate vitamin D intake, especially for those at risk of deficiency due to limited sun exposure or dietary factors. Supplements are available as vitamin D2 and D3, with D3 potentially being more effective at raising blood levels. Plant-based D3 options from lichen are available for vegans. Many health professionals recommend supplements for safe and consistent intake, avoiding excessive sun exposure risks.

Dietary vs. Sun Exposure vs. Supplements

Here is a comparison of the primary ways to obtain vitamin D.


Feature	Sun Exposure	Dietary Sources	Supplements
Convenience	Dependent on weather, latitude, and season	Varies by food availability and preference	Consistent and readily available
Risks	Skin cancer risk from excessive UV exposure	Few risks, but natural food sources are limited	Toxicity risk with excessive intake; dosage must be managed
Control over dose	Minimal control; affected by many variables	Fair control; requires mindful eating	Precise control over dosage
Reliability	Unreliable in winter, high latitudes, or with sunscreen use	Natural sources are sparse; fortified foods vary	Highly reliable for consistent intake
Primary Form	Produces Vitamin D3	Provides both D2 (plants/fungi) and D3 (animals)	Available in D2 or D3

What happens after absorption?

Vitamin D from any source is inactive and must be converted in the liver and kidneys to its active form, calcitriol. Calcitriol is essential for regulating calcium and phosphate metabolism, supporting bone health and other functions.

Conclusion

To determine where does H get vitamin D from, we see it comes from sun exposure, dietary sources like fatty fish and fortified foods, and supplements. As sun exposure is unreliable for many, diet and supplements are crucial for maintaining sufficient levels. Combining these sources as needed helps manage vitamin D levels for optimal health.

Learn more about vitamin D and its functions by visiting the National Institutes of Health Office of Dietary Supplements website: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/.

Frequently Asked Questions

Relying solely on sun exposure is often insufficient. Factors like your geographic location, the season, time of day, and skin pigmentation all affect how much vitamin D your skin can produce. The use of sunscreen also reduces synthesis.

Fatty fish and fish liver oils are the best natural sources of vitamin D. Options include salmon, trout, tuna, mackerel, and cod liver oil. Egg yolks and beef liver also contain smaller amounts.

Yes, fortified foods are a key source of vitamin D in many diets. Products like milk, some cereals, and orange juice have vitamin D added to help meet daily requirements, especially in countries with limited winter sun.

Yes, vitamin D2 comes from plant and fungal sources (like UV-exposed mushrooms), while vitamin D3 is produced by animal skin and found in animal products. Studies suggest that D3 is more effective at raising and maintaining blood levels of vitamin D.

Individuals with limited sun exposure (due to location, lifestyle, or clothing), people with darker skin, older adults, and those with conditions affecting fat absorption (e.g., Crohn’s disease) are at a higher risk of deficiency.

Supplements provide a precise and reliable way to get enough vitamin D, removing the uncertainty of sun exposure and limited food sources. They are particularly beneficial for those at high risk of deficiency or who have trouble absorbing the vitamin.

Sufficient vitamin D intake is essential for maintaining strong, healthy bones by aiding in the absorption of calcium and phosphorus. It also plays a crucial role in immune function, reducing inflammation, and regulating cell growth.