Can you produce vitamin D without sun? Exploring dietary and supplemental options

October 10, 2025 •

3 min read

According to the National Institutes of Health, almost one in four U.S. adults have inadequate vitamin D blood levels, which can impact bone and overall health. While sun exposure is a primary source, many people wonder, 'Can you produce vitamin D without sun?'. This article explores the effective dietary and supplemental paths to achieve sufficient vitamin D, regardless of your sunlight exposure.

Quick Summary

It is possible to get vitamin D from sources other than the sun, namely food and supplements. Dietary sources include fatty fish and fortified products, while supplements offer a reliable, controlled way to maintain adequate levels, especially for those with limited sun exposure.

Key Points

Supplements are a reliable option: High-quality vitamin D3 supplements are a safe and effective way to ensure adequate vitamin D levels, especially for those with limited sun exposure.
Food fortification helps: Many staple foods like milk (dairy and plant-based), cereals, and orange juice are fortified with vitamin D, helping to increase daily intake.
Fatty fish are rich sources: Naturally occurring vitamin D is found in fatty fish like salmon, tuna, and mackerel, and also in cod liver oil and egg yolks.
Some mushrooms contain vitamin D2: Certain mushrooms exposed to UV light can produce vitamin D2, offering a plant-based source for vegans and vegetarians.
Sun exposure is not always sufficient: Factors like skin tone, age, location, and sunscreen use can limit the body's ability to produce enough vitamin D from sunlight alone.
Professional guidance is advised: Consulting a healthcare provider is the best way to determine your specific vitamin D needs and whether supplementation is necessary.
D3 is more effective than D2: The supplement form D3 (cholecalciferol) has been shown to raise blood vitamin D levels more effectively and for longer than D2 (ergocalciferol).

Understanding the 'Sunshine Vitamin' Beyond the Sun

Vitamin D is a crucial fat-soluble nutrient important for regulating calcium and phosphate, vital for strong bones, muscle function, nerve signaling, and a healthy immune system. While our bodies make vitamin D from sun exposure, many factors can limit this process, highlighting the need for alternative sources.

Dietary Sources of Vitamin D

While few foods naturally contain significant vitamin D, some animal-based options are good sources.

Natural food sources of vitamin D

Fatty Fish: Salmon, tuna, mackerel, and sardines are top natural sources. Wild salmon generally has more vitamin D than farmed.
Cod Liver Oil: A concentrated source providing a substantial amount of vitamin D.
Egg Yolks: Vitamin D content varies based on the hen's diet and sun exposure.
Mushrooms: UV-exposed mushrooms are a plant-based source of vitamin D2, but most commercially grown mushrooms contain little.
Beef Liver: Contains a smaller amount of vitamin D.

Fortified food sources

Many foods are fortified with vitamin D to help boost intake.

Milk: Dairy and many plant-based milks are commonly fortified.
Cereals and Oatmeal: Many breakfast cereals and some oatmeal contain added vitamin D.
Orange Juice: Some brands are fortified.
Yogurt and Margarine: Select brands include added vitamin D.

The Role of Vitamin D Supplements

Supplements are a reliable way to meet vitamin D needs for many, particularly those with limited sun exposure. They come as D2 (ergocalciferol) and D3 (cholecalciferol).

Vitamin D supplement comparison


Feature	Vitamin D2 (Ergocalciferol)	Vitamin D3 (Cholecalciferol)
Source	From UV irradiation of ergosterol in yeast and plants.	Typically from lanolin or lichen.
Effectiveness	Increases blood vitamin D levels, but generally less effective long-term than D3.	More effective at increasing and maintaining serum 25(OH)D levels.
Vegan Option	Plant-based and suitable for vegans.	Vegan options from lichen are available.
Availability	Available by prescription and over-the-counter.	Widely available over-the-counter.

Take vitamin D supplements with a meal containing fat for better absorption. Consult a healthcare professional for guidance based on individual needs.

Factors Limiting Sun-Derived Vitamin D

Geography and Season: In northern latitudes, vitamin D synthesis is limited during autumn and winter.
Skin Pigmentation: Melanin reduces the ability to produce vitamin D from sunlight; darker skin requires more sun exposure.
Limited Sun Exposure: Individuals indoors during peak sun hours or who cover their skin may not get enough exposure.
Age: Vitamin D production efficiency decreases with age.
Sunscreen: Blocks UVB rays needed for vitamin D synthesis. Health experts advise getting vitamin D from other sources rather than unprotected sun exposure.

Who is at risk for vitamin D deficiency?

Several factors increase the risk of vitamin D inadequacy:

Malabsorption Issues: Conditions like Crohn's disease or celiac disease can impair absorption.
Obesity: Vitamin D is stored in fat tissue, reducing its bioavailability. People with obesity may need higher supplement amounts.
Breastfed Infants: Breast milk may not provide enough vitamin D, requiring supplementation.
Certain Medications: Some medications can interfere with vitamin D absorption and metabolism.

Conclusion: Strategic Nutrition is Key

Yes, you can obtain sufficient vitamin D without relying on the sun. Given the risks of excessive sun exposure, alternative sources are a safer strategy. Incorporating fatty fish, fortified dairy and plant-based milks, and fortified cereals into your diet can boost intake. High-quality D3 supplements are also an effective way to fill nutritional gaps for bone and immune health. Discuss your needs with a healthcare provider to determine the best approach.

For more information, the NIH Office of Dietary Supplements offers comprehensive fact sheets.

Frequently Asked Questions

It is very difficult to get sufficient vitamin D from diet alone because few foods naturally contain high amounts of it. While incorporating fortified foods and fatty fish helps, most people with limited sun exposure will also need a supplement to meet their daily requirements.

Studies suggest that vitamin D3 (cholecalciferol) supplements are more effective at raising and maintaining vitamin D blood levels compared to vitamin D2 (ergocalciferol). However, both forms can help correct a deficiency.

Yes. While limited, vegan sources include mushrooms treated with UV light, fortified plant-based milks and cereals, and supplements derived from lichen.

No, glass blocks the UVB rays necessary for your skin to produce vitamin D. To get vitamin D from the sun, your skin must be exposed to direct sunlight outdoors.

Symptoms of a deficiency can include fatigue, bone pain, muscle weakness, and mood changes, but many people show no symptoms. A blood test measuring your 25-hydroxyvitamin D levels is the most accurate way to confirm a deficiency.

Yes, excessive intake of vitamin D, almost always from supplements, can lead to vitamin D toxicity. This can cause high calcium levels in the blood and lead to side effects like nausea, vomiting, confusion, and in extreme cases, kidney problems.

The time it takes to restore vitamin D levels depends on the severity of the deficiency. It generally takes several weeks of consistent supplementation for levels to return to a normal range, though the exact timeframe can vary.

While fortified foods are an important part of a diet for those with limited sun exposure, relying on them alone may not be sufficient. Checking nutrition labels and considering a supplement is often necessary to ensure adequate daily intake.