Vitamin D deficiency is surprisingly common, with studies estimating that about 20% of Americans don't get enough of this essential nutrient, which plays a key role in bone health as well as supporting nerve, muscle, and immune function.

While supplements can be helpful in bridging the gap, certain foods—and of course, exposure to sunlight—can also contribute significantly to your daily intake of vitamin D. Adults generally need about 600 international units (IU) of vitamin D per day until they turn 71, at which point the recommended intake increases to 800 IU. Here are five foods and drinks that can help you meet your vitamin D needs.

1. Fatty Fish

Fatty fish such as salmon, mackerel, and sardines are among the richest natural sources of vitamin D3, the form that is most easily utilized by the body. According to Morgan Walker, MS, RD, LDN, a sports nutritionist and adjunct professor at Lebanon Valley College, a 3-ounce serving of rainbow trout provides 645 IU of vitamin D, while the same serving size of sockeye salmon offers 570 IU. Canned tuna and salmon are also convenient, economical options that can be added to salads, sandwiches, or used to make fish "burger" patties.

2. Egg Yolks

Egg yolks contain vitamin D3, though not as much as fatty fish. One large egg contains 44 IU of vitamin D. Eggs are versatile and can be enjoyed in many ways, but deviled eggs—where the yolks are highlighted—are a great option. Jen Hernandez, RDN, CSR, a registered dietitian nutritionist specializing in renal health, recommends swapping mayo for low-fat Greek yogurt to add more protein. Other easy ways to incorporate eggs include omelets, fried rice, and baked goods.

3. UV-Exposed Mushrooms

Not many plant-based foods naturally contain vitamin D, but mushrooms exposed to ultraviolet (UV) light do. A 1/2 cup of sliced white UV-exposed mushrooms provides about 366 IU of vitamin D. Look for labels that say "High Vitamin D" or "UV-Exposed." Mushrooms like shiitake, button, and oyster contain ergosterol, a precursor to vitamin D. When exposed to UV rays, ergosterol is converted into vitamin D2, similar to the way sunlight triggers vitamin D production in our skin. Hernandez enjoys roasting mushrooms or using them in risottos, but she recommends pairing them with healthy fats to aid in vitamin D absorption, as vitamin D is fat-soluble.

4. Fortified Dairy Products and Plant Milks

Fortified dairy products, such as cow's milk and yogurt, typically provide vitamin D3, while most plant-based milks (such as soy, almond, or oat milk) are fortified with vitamin D2. One cup of fortified 2% reduced-fat milk contains 120 IU, while a cup of fortified soy, almond, or oat milk provides between 100 and 144 IU, depending on the type. Fortified dairy and plant milks are an excellent option for increasing your vitamin D intake, especially for individuals who don't consume much fatty fish or eggs.

5. Fortified Cereals

Many breakfast cereals are fortified with vitamin D. The amount varies by brand, but most cereals typically provide around 80 IU per serving. While Dr. Frank Dumont, MD, FACP, an internal medicine physician at Virta Health, does not recommend relying heavily on processed fortified cereals for your vitamin D intake, they can still be a good option, especially for children who may not eat mushrooms, eggs, or fish. They can be a convenient way to boost your intake.

When You Might Need a Vitamin D Supplement

If you regularly spend time outdoors, as research suggests that sunscreen does not block vitamin D production, and you have a diet full of vitamin D-rich foods, you probably don’t need a supplement. However, experts suggest that people who live in areas with limited sun exposure, spend most of their time indoors, have darker skin, or follow a vegan or vegetarian diet may benefit from supplementation. Many people with a vitamin D deficiency may not show symptoms, but possible signs include muscle weakness, bone pain, and fatigue.

A simple blood test can confirm your vitamin D levels, and it’s recommended that you get tested at least twice a year, ideally around daylight savings time, to check your levels.