Which is the richest source of vitamin D? Exploring Your Nutritional Options

November 1, 2025 •

4 min read

According to the National Institutes of Health, a single tablespoon of cod liver oil provides a massive 1,360 IU of vitamin D, making it the richest source of vitamin D among common dietary options. However, several other foods and supplements also pack a powerful punch to help you meet your daily requirements.

Quick Summary

Cod liver oil is the single richest dietary source of vitamin D per serving, followed by fatty fish like salmon and UV-exposed mushrooms. Fortified foods and supplements are also key for maintaining adequate levels of this vital nutrient, as few foods contain substantial amounts naturally.

Key Points

Richest Dietary Source: Cod liver oil is the single most concentrated food source of vitamin D, providing 1,360 IU per tablespoon.
Excellent Natural Food Sources: Fatty fish such as salmon, trout, and mackerel are also exceptionally high in vitamin D3.
Plant-Based Options: UV-exposed mushrooms are a valuable vegetarian and vegan source, producing vitamin D2 when treated with light.
Common Fortified Foods: Many people get vitamin D from fortified products like milk (dairy and plant-based), cereals, and orange juice.
Sunlight is Key, with Caution: The body produces vitamin D from sun exposure, but it's important to limit unprotected exposure due to skin cancer risks.
Supplements are a Reliable Choice: For consistent intake, especially when sun exposure is limited, supplements are a safe and effective option.

Cod Liver Oil: The Undisputed Dietary Champion

When it comes to dietary sources, cod liver oil stands out as the most concentrated source of vitamin D. A single tablespoon can deliver an astonishing 1,360 IU, providing 170% of the Daily Value for adults. This nutrient-rich oil has been used for centuries as a natural remedy for a variety of ailments and is also an excellent source of omega-3 fatty acids and vitamin A. However, the high vitamin A content is also a consideration, as excessive amounts can be harmful, particularly for pregnant individuals. For most people, a limited daily dose is sufficient, and it's essential to monitor overall intake from all sources to avoid toxicity.

The Power of Fatty Fish

Beyond concentrated oils, fatty fish and seafood are among the best natural food sources of vitamin D3, the form produced in animals. The vitamin is stored in the fish's fat and liver, making options like salmon, trout, and mackerel particularly potent.

Wild-caught sockeye salmon: A 3-ounce serving offers around 570 IU of vitamin D.
Farmed rainbow trout: Provides approximately 645 IU per 3-ounce serving.
Canned tuna (light, in water): Delivers around 40 IU per 3-ounce serving.

The vitamin D content can vary widely based on the species, whether it was wild-caught or farmed, and where it was harvested. For example, wild salmon generally contains more vitamin D than farmed varieties.

Plant-Based Sources: UV-Treated Mushrooms

For those following a vegetarian or vegan diet, mushrooms are the only substantial plant-based food source of vitamin D. Like humans, mushrooms can produce their own vitamin D when exposed to ultraviolet (UV) light. However, they produce vitamin D2, a slightly different form than the D3 found in animal products. Many commercially grown mushrooms are cultivated in the dark and have very low levels, so it's crucial to look for labels indicating they were exposed to UV light.

UV-exposed cremini mushrooms: A cup can contain a very high amount of vitamin D, sometimes over 1,000 IU.
Wild mushrooms (maitake, morel): These varieties can also be naturally high in vitamin D2 due to sun exposure.

Fortified Foods: The Mainstay for Many Diets

Because very few foods naturally contain significant amounts of vitamin D, many staple food products are fortified with it. This provides a reliable source for a large portion of the population.

Fortified milk: Most cow's milk in the U.S. is fortified, providing around 120 IU per cup.
Fortified plant-based milks: Soy, almond, and oat milks are often fortified with similar amounts of vitamin D.
Fortified cereals and orange juice: Many breakfast cereals and some brands of orange juice are also supplemented with vitamin D.

When relying on fortified foods, always check the nutrition label, as the amount can vary by brand and country.

Comparison of Vitamin D Sources

This table provides a quick reference for the vitamin D content of various dietary sources.


Food Source	Vitamin D Content per Serving	Primary Form	Notes
Cod Liver Oil	1,360 IU per tbsp	D3	Highest dietary source; also high in Vitamin A
UV-Exposed Cremini Mushrooms	~1,100 IU per cup	D2	Excellent vegan option; content varies
Farmed Rainbow Trout	645 IU per 3 oz	D3	A consistently high animal source
Wild Sockeye Salmon	570 IU per 3 oz	D3	Content can vary by catch location
Fortified Plant-Based Milk	100-144 IU per cup	D2/D3	Check labels for specific fortification info
Fortified Cow's Milk	~120 IU per cup	D3	Fortification levels vary by country
Large Egg (Yolk)	~44 IU per egg	D3	Content depends on hen's diet and sun exposure

The Role of Sunlight and Supplements

While food is a crucial source, the body's primary natural mechanism for producing vitamin D is through sun exposure. When bare skin is exposed to UVB radiation, the body synthesizes vitamin D3. However, several factors can limit this process, including geographic location, season, skin pigmentation, age, and sunscreen use. Health experts often advise caution with prolonged sun exposure due to the risk of skin cancer.

For those who cannot get sufficient vitamin D from sunlight, dietary supplements are a safe and effective alternative. These are widely available in both D2 and D3 forms, and some evidence suggests that D3 may be slightly more potent in raising blood levels. Consult a healthcare provider to determine if supplementation is necessary.

Conclusion

While sunlight is a major factor, cod liver oil is the most concentrated dietary source of vitamin D available. Beyond this supplement, a balanced diet including fatty fish, UV-exposed mushrooms, and fortified foods like milk and cereals provides a variety of options for meeting your daily needs. For many, a combination of dietary sources and safe sun exposure, with supplements as needed, is the best strategy for maintaining optimal vitamin D levels. It is always recommended to consult with a healthcare professional to assess your individual needs.

The information provided in this article is for informational purposes only and is not a substitute for professional medical advice. Always consult a healthcare provider for personalized advice regarding your health and nutritional needs.

Frequently Asked Questions

Sunlight is the body's primary natural way of producing vitamin D3. However, factors like season, latitude, skin color, and sunscreen use can limit production. Experts advise a balance, often recommending supplements or food sources to maintain levels while limiting skin cancer risk from overexposure.

Vitamin D2 (ergocalciferol) is produced by plants and fungi, while vitamin D3 (cholecalciferol) comes from animal sources and is synthesized by the skin in response to sunlight. Some studies suggest D3 may be more effective at raising blood levels, but both forms increase overall vitamin D status.

No, only mushrooms exposed to ultraviolet (UV) light are good sources. Most commercially grown mushrooms are cultivated in the dark and contain very little vitamin D. Look for labels indicating 'UV-exposed' or 'high in vitamin D'.

Vegans and vegetarians can obtain vitamin D from UV-exposed mushrooms and fortified foods like plant-based milks, cereals, and tofu. Some vitamin D3 supplements are now derived from lichen, a vegan-friendly source.

It is difficult to get a toxic amount of vitamin D from food alone. High intake is usually caused by excessive supplementation. Cod liver oil is a potent source, and intake should be monitored, especially due to its high vitamin A content.

Fortified foods are a significant source of vitamin D for many people, but they may not be sufficient on their own, especially for those with low sun exposure or other risk factors for deficiency. The amount of fortification varies by product and brand.

Vitamin D is crucial for absorbing calcium and phosphorus, which are essential for strong bones and teeth. It also supports immune function, muscle movement, and nerve health.

The effect of cooking varies. One study found that baking farmed salmon did not significantly reduce its vitamin D content, while frying it resulted in a roughly 50% loss.