Good sources of vitamin D are few and far between. This is unfortunate, given the importance of the "sunshine and seafood" nutrient for lowering the risk of cancer, many infectious diseases, osteoporosis and more. Although sun exposure is the most reliable source of the vitamin, it’s often impossible to get enough sun in winter months to supply our bodies with adequate vitamin D.
So we need to turn to our diet, and for that, fish are the best sources of this crucial nutrient by far.
Fish species vary in the amount of vitamin D they contain, and there are even fairly substantial seasonal and geographic variations within fish of the same species. Fish such as halibut, carp, mackerel, eel and salmon contain over 700 International Units, abbreviated as IU, per serving. That makes them among the most vitamin D-rich foods, according to the USDA National Nutrient Database for Standard Reference (USDA, 2015).
Health benefits of vitamin D
Vitamin D in its most common form, vitamin D3, is crucial for your bones, immune system, muscles and even your brain. It’s a natural anti-inflammatory (like the omega-3 fatty acids in seafood). But vitamin D deficiencies are common worldwide, and can increase your risk of bone fractures, cancers and having worse symptoms from infectious diseases (Mendes et al, 2020).
The U.S. National Institutes of Health recommend that adults get a 600 IU dosage of vitamin D3 from their diets each day (NIH, 2021). But most Americans consume a fraction of that; an average dosage of 204 IU in men, and 168 IU in children (NIH, 2021).
Research has also found a link between vitamin D and mental health, though results are mixed. For instance, one study found that people with lower vitamin D3 levels were more likely to suffer from depression (Ju et al., 2013). Another study found vitamin D3 supplements helped alleviate symptoms of anxiety, but not depression (Zhu et al., 2020). Meanwhile, others have found strong links between postpartum depression and low vitamin D levels (Aghajafari et al., 2018).
Much of our vitamin D comes from the sun, or more specifically, as a result of the fraction of ultraviolet light know as UV-B penetrating the skin and converting cholesterol to vitamin D. But in winter months, those of us in northerly latitudes get insufficient sun exposure to make enough vitamin D for our needs.
Dietary vitamin D is a must for northerners in the winter months, and fortunately there are a number of ways to get it.
Many people take vitamin D supplements, which can be a great way to increase your vitamin D consumption. But recent research has suggested that it’s even better to get this nutrient the old-fashioned way: through a combination of sun and diet (Michos et al., 2021). And what’s the best source of dietary vitamin D? Fish, especially wild salmon.
Wild salmon is a food rich in vitamin D
When researchers estimate the nutrient content of food, they typically examine raw foods. But cooking often alters the nutrients in food. That’s why researchers at the Boston University Medical Center tested several species of cooked fish to find out the effects of baking and frying on their vitamin D content (Lu et al, 2007).
The researchers found that wild salmon beat out other fatty fish, and especially farmed salmon, when it came to vitamin D content. The wild salmon had 988 IU of vitamin D per 3.5 ounce serving, almost two-thirds more than the 600 IU recommendation.
Farmed salmon, on the other hand, had only 245 IU, just 25 percent of the vitamin D content of wild salmon. Even more surprisingly, they found that other fatty fish also fell short of wild salmon. So how much vitamin D do various fish have? These were the results, ranked from most to least vitamin D per 3.5 ounce serving:
How you cook your fish matters, too. When the researchers baked a 3.5 oz serving of farmed salmon, it lost only 5 IU of vitamin D. But when it was fried in vegetable oil, it lost half of its vitamin D content, dropping to 123 IU.
Vitamin D in Vital Choice fish and other products
We put our own Vital Choice products to the test to see how much vitamin D they contained per serving. In our products, wild salmon is also the best source of vitamin D, followed by canned tuna and cod liver oil.
Compare these to some other sources of vitamin D, according to the USDA:
The Bottom Line
Soaking up some rays has its time and place, but there are plenty of ways to get vitamin D from your diet. Wild-caught salmon is the best source of dietary vitamin D (along with many other healthy nutrients like omega-3s, selenium and more). Be sure to bake it, not fry it, to retain as much of that goodness as possible.