The Reigning Champions: Fatty Fish
When considering which protein source has the most vitamin D, the clear winners are fatty or oily fish. These fish naturally store this fat-soluble vitamin, which is why they are such potent sources.
Salmon
Wild-caught salmon is particularly notable for its high vitamin D content. The amount can vary widely depending on the species and where it was caught, but it often provides an exceptional quantity per serving. For example, 3.5 ounces (100 grams) of salmon from the Baltic Sea was found to contain between 556 and 924 IU of vitamin D, potentially exceeding the daily value. In contrast, farmed salmon typically contains only about 25% of the vitamin D found in wild salmon, but many brands still offer substantial amounts.
Other Oily Fish
- Rainbow Trout: A 3-ounce serving of cooked, farmed rainbow trout provides around 645 IU, making it a very strong source.
- Mackerel: Mackerel is also an excellent option, providing about 643 IU per 3.5-ounce serving.
- Sardines and Herring: Small, oily fish like sardines and herring are also great sources. Canned sardines offer about 193 IU per 3.5-ounce serving, while fresh Atlantic herring contains around 167 IU. They also offer healthy omega-3 fatty acids.
Fortified Foods and Other Animal Proteins
For those who don't regularly consume fatty fish, or want to supplement their intake, several other protein-rich foods offer vitamin D, often through fortification.
Fortified Dairy and Plant-Based Milks
Because few foods are naturally high in vitamin D, many products are fortified to help consumers meet their daily needs. This is a crucial source for many people, especially those who avoid meat or fatty fish.
- Cow's milk: In the United States, almost all cow's milk is fortified with vitamin D. A 1-cup serving of 2% milk contains about 111 IU.
- Soy milk: Many plant-based milk alternatives are also fortified. A cup of sweetened, plain soy milk can provide around 185 IU.
- Yogurt: Fortified yogurts are another excellent way to add both protein and vitamin D to your diet.
Eggs
Eggs are a versatile and common protein source that contains a small amount of vitamin D. The vitamin D is primarily located in the yolk, so eating the whole egg is essential. The amount of vitamin D can vary depending on the hen's diet and sun exposure. One large egg contains about 41 IU, a modest but helpful amount.
Cod Liver Oil and Beef Liver
- Cod Liver Oil: This supplement is an extremely concentrated source of vitamin D, providing about 450 IU per teaspoon. It's a great option for those who don't eat fish but need to boost their intake.
- Beef Liver: A 3.5-ounce serving of cooked beef liver contains a smaller amount of vitamin D, about 42 IU. While nutrient-dense, it is also high in cholesterol and should be consumed in moderation.
Plant-Based Proteins
For vegetarians and vegans, naturally occurring vitamin D is primarily limited to mushrooms. Like humans, mushrooms can produce vitamin D when exposed to UV light.
UV-Treated Mushrooms
Commercially grown mushrooms are typically raised in the dark and have very low vitamin D levels. However, some brands expose their mushrooms to ultraviolet (UV) light, significantly boosting their vitamin D2 content. For example, 1 cup of UV-exposed cremini mushrooms can contain up to 1100 IU, a remarkable amount. It is important to note that vitamin D2 may not be as effective as D3 (the animal-derived form) at raising blood vitamin D levels, but it is still beneficial.
Comparison of Vitamin D Protein Sources
| Protein Source | Vitamin D per Serving (IU) | Serving Size | Notes |
|---|---|---|---|
| Cod Liver Oil | ~450+ | 1 tsp | Extremely concentrated; high in omega-3s. |
| Rainbow Trout | 645 | 3 oz, cooked | Excellent natural source. |
| Wild Salmon | 570+ | 3 oz, cooked | Very high natural source; wild often higher than farmed. |
| Mackerel | 643 | 3.5 oz, cooked | Another very high source among fatty fish. |
| UV-Exposed Mushrooms | up to 1100 | 1 cup, sliced | Plant-based source of D2; content varies. |
| Fortified Soy Milk | ~100–144 | 1 cup | Good plant-based alternative. |
| Fortified Cow's Milk | ~120 | 1 cup | Most milk is fortified in the US. |
| Canned Tuna (Light) | ~40 | 3 oz, drained | Lower mercury than albacore, contains vitamin D. |
| Egg Yolk | ~41 | 1 large egg | Contains D in the yolk; amount depends on hen's diet. |
| Beef Liver | ~42 | 3 oz, braised | Contains small amounts, but also high in cholesterol. |
Conclusion
To determine what protein has the most vitamin D, fatty fish like salmon, trout, and mackerel stand out as the most potent natural dietary sources. For a concentrated boost, cod liver oil is an excellent supplement option. Incorporating fortified products, such as dairy or plant-based milks, can also significantly contribute to your daily intake. For those on a vegan or vegetarian diet, UV-treated mushrooms are a valuable protein-rich source of vitamin D2. A varied diet that includes these options can help ensure adequate vitamin D levels, promoting bone health, immune function, and overall well-being.
Maximize Your Vitamin D and Protein Intake
- Prioritize Wild Fish: When possible, choose wild-caught salmon and other fatty fish for the highest natural vitamin D content. Pair with healthy fats like avocado or olive oil to enhance absorption.
- Choose Fortified Options: Select milk, plant-based milks, yogurts, and cereals that are clearly labeled as fortified with vitamin D to reliably increase your intake.
- Incorporate Egg Yolks: Don't skip the yolks, as they contain the vitamin D. Adding eggs to meals is an easy way to get some extra vitamin D, especially from pasture-raised hens.
- Explore UV-Treated Mushrooms: Look for mushrooms specifically treated with UV light in your local grocery store. These can be a powerful plant-based source of vitamin D2, but check the labels for verification.
- Consider Cod Liver Oil: For a reliable and high-dose supplement, cod liver oil is an effective choice, especially if you have dietary restrictions or don't eat fish often.
