This time of year, many are seeking to enhance their diets with foods high in vitamin D. But how can you ensure you're getting enough vitamin D?

To harness the power of vitamin D for bone health and immune support, it is essential to incorporate a variety of foods into your diet. While few foods contain adequate amounts of vitamin D, also known as calciferol, a healthy diet is always the foundation to adequate nutrient intake. A multi-vitamin with vitamin D is good dietary insurance to help fill in the gaps when diet alone isn’t enough.

First off, what is vitamin D? And why is it hard to get enough vitamin D in the diet?

Vitamin D vs. calciferol

Vitamin D – or, as you now know, calciferol – is a fat-soluble vitamin that plays a crucial role in supporting bone health by promoting calcium, magnesium, and phosphorus absorption. Among its many other functions vitamin D benefits immune function.

The body makes natural calciferol when skin is exposed directly to the sun; spending as little as 20 minutes each day in short sleeves outside under a clear blue sky can be enough for the body to make its own daily needs of calciferol.

But as the days get shorter and colder, especially if you live in northern latitudes, making enough vitamin D for daily needs can be challenging, risking a deficiency. Older adults, people with more melanin in the skin, and those who live in colder northern latitudes are most at-risk for vitamin D deficiency.

How much vitamin D does the body need daily? The National Institutes of Health (NIH) recommends a minimum of 600 IU of vitamin D to maintain daily health; for adults older than 70, the NIH recommends 800 IU to avoid deficiency. Depending on whether you are starting out with low vitamin D levels or have risk factors for low levels, you might need more than these minimum recommendations.

Types of vitamin D found in foods and in supplements

There are two well-known forms of vitamin D: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Both forms are fat soluble and vital for human health, but they are derived from different sources and metabolized differently by the body.

  1. Ergocalciferol (vitamin D2) is plant-based and primarily obtained from yeast and fungi; it is a less potent form of vitamin D.
  2. Cholecalciferol (vitamin D3) is the form produced in the skin when exposed to sunlight and is also found in small amounts in animal-based foods, as well as foods that have been fortified with D, including dairy and plant-based milk, cereals, breads, and orange juice.
  3. Both vitamin D2 and D3 are available in over-the-counter supplement forms.

The body converts both forms first into calcidiol and then into calcitriol, the active form of vitamin D.

Research suggests that vitamin D3 is more effective at raising and maintaining overall vitamin D levels in the body compared to vitamin D2. This difference is important when choosing vitamin D supplements, as many experts recommend prioritizing D3 for optimal health benefits.

All Thorne supplements with vitamin D contain vitamin D3, the more potent and better-absorbed form.

5 foods high in vitamin D that can help boost your vitamin D intake

1. Fatty Fish – Fatty fish, such as salmon, mackerel, and sardines, are some of the richest food sources of vitamin D. A single serving of salmon provides an average of 570 IU of vitamin D. The combination of healthy omega-3 fatty acids and vitamin D makes fatty fish a good choice for cardiovascular and bone health.

When shopping, look for wild-caught fish when possible, as they generally contain higher levels of nutrients compared to farmed counterparts. For example, one evaluation of vitamin D content of fish found wild-caught salmon contained 988 IU of vitamin D compared to only 250 IU in farm-raised salmon.1 Adding fatty fish to your diet a couple of times a week can contribute to your vitamin D levels.

2. Cod Liver Oil

Cod liver oil is a classic source of vitamin D, providing about 450 IU of vitamin D per teaspoon. Although it may not be a common addition to everyone's diet (admittedly, the name causes this writer to make a face not unlike the green nauseated emoji face), its concentrated nutrient profile makes it an option for those seeking to boost their vitamin D levels quickly.

Cod liver oil is also rich in omega-3 fatty acids, which support heart health and brain function.

Keep in mind that cod liver oil is also a very rich source of vitamin A at 4,500 IU per teaspoon. Therefore, if you want to boost your vitamin D levels, it’s best not to do so by taking multiple teaspoons of cod liver oil.

3. Milk fortified with vitamin D

Many people find it challenging to obtain sufficient vitamin D through natural food sources alone, which is where fortified foods come into play. Dairy milk – and even nondairy alternatives like almond or soymilk – are often fortified with vitamin D3, making them a practical choice for enhancing your daily intake.

Nutritional labels on milk usually show vitamin D content in micrograms (mcg), and 1 mcg vitamin D equals about 40 IU.  One 8-ounce serving of milk fortified with vitamin D provides 2.5 mcg, or 100 IU, of vitamin D.

If you’re a milk-and-cereal-for-breakfast kind of person, cereals are also vitamin D-fortified foods. When shopping in the cereal aisle at the store, check the nutrition labels to ensure you’re getting an adequate amount of vitamin D, and always opt for cereals without empty calories from excess amounts of sugar.

4. Egg Yolks

Rich in protein and vitamins A and B12, eggs are a staple in many diets, and egg yolks in particular are a source of vitamin D. One large egg yolk contains about 37 IU of vitamin D, which, while small compared to fatty fish or fortified milk, can add up when included as part of a balanced diet. However, according to one study, free-range, pasture-raised chickens can produce 3-4 times this amount of vitamin D.2 And chickens fed vitamin D-enriched feed can even produce eggs with up to 6,000 IU of vitamin D.

Eggs are versatile and can be incorporated into meals in countless ways, from breakfast scrambles to hearty mushroom frittatas (see #5 below). The fat in the yolk also aids in the absorption of fat-soluble vitamins, making them an excellent complement to your vitamin D-rich foods.

5. Mushrooms

So far, this list has focused on mostly animal-based products. For those following vegan or vegetarian diets, foods high in vitamin D are harder to come by. Mushrooms are special among vegetarian food sources for their ability to produce vitamin D2 when exposed to UV light.

While most conventionally grown mushrooms contain small amounts of vitamin D – about 10 IU per 1 cup raw – mushrooms that were exposed to UV light during growing contain significantly more vitamin D. According to the NIH, a 1-cup serving of raw white mushrooms that were exposed to UV light can provide more than 700 IU of vitamin D.3 

Incorporating mushrooms into your meals not only enhances flavor and texture but also adds a significant amount of this essential nutrient, particularly for those following vegan or vegetarian diets.

The next time you’re planning your meals, consider how you can bring a little sunshine to your plate with these foods high in vitamin D.

When you need a calciferol supplement

Awareness continues to grow about the importance of calciferol. When sunlight or dietary vitamin D is not sufficient to ensure adequate vitamin D intake, it’s important to take a vitamin D supplement.

Thorne offers several vitamin D supplements (as cholecalciferol; D3) in both liquid and capsule forms to support your needs.

Looking for something with more nutrient support? Check out Thorne’s multi-vitamins with cholecalciferol (vitamin D3). Or shake up your supplement regimen with a plant-forward formula featuring antioxidants and vitamin D3, like Thorne’s MediClear lineup and Thorne’s Daily Greens Plus, a unique greens powder with vitamin D.

If you’re wondering about your vitamin D levels, Thorne has you covered there too. Thorne’s simple, at-home Vitamin D Test requires just a finger prick to test your blood levels of vitamin D. Results are accompanied by diet, lifestyle, and supplement recommendations.

References

  1. Lu Z, Chen T, Zhang A, et al. An evaluation of the vitamin D3 content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D. J Steroid Biochem Mol Biol 2007;103(3-5):642-644.
  2. Kühn J, Schutkowski A, Kluge H, et al. Free-range farming: a natural alternative to produce vitamin D-enriched eggs. Nutrition 2014;30(4):481-484.
  3. National Institutes of Health: Vitamin D. Vitamin D – Health Professional Fact Sheet (nih.gov) [Accessed October 11, 2024]