Vitamin D is a type of nutrient that the body produces when a person's skin has exposure to direct sunlight. People can also consume vitamin D, but it is not naturally present in many foods. High quantities of vitamin D are present in oily fish and certain types of mushrooms.

According to the Office of Dietary Supplements (ODS), the key benefit of vitamin D is that it helps keep a person's bones, muscles, and nerves healthy. It also contributes to a healthy immune system.

It is present in egg yolks if the chickens laying them are free-range. Some mushrooms also contain vitamin D. However, no other plant-based foods produce vitamin D. For people whose diets are mostly vegetarian or vegan, and for people who do not or cannot spend a lot of time outdoors, it can be difficult to get enough vitamin D. If a person has concerns that they are not getting enough vitamin D from direct sunlight, consuming the following foods will help increase the overall amount they have in their bodies.

Oily fish

Oily fish, as well as oils from fish, have some of the highest quantities of vitamin D in food sources. These may include:

• Cod liver oil: This contains 450 international units (IU) per teaspoon, which is 75% of a person's recommended daily allowance (RDA)
• Herring: This contains 306 IU per fillet, dry-cooked, which is 51% of a person's RDA
• Swordfish: This contains 706 IU per piece, dry-cooked, which is 117% of a person's RDA

Mushrooms

If a person does not like fish, or if they are vegetarian or vegan, specific mushrooms may be an option. Some types of mushrooms contain high amounts of vitamin D. These include:

• Raw maitake mushrooms: These contain 562 IU per 50 grams (g), which is 94% of a person's RDA
• Dried shiitake mushrooms: These contain 77 IU per 50 g, which is 12% of a person's RDA

Mushrooms with exposure to ultraviolet (UV) light can also contain large amounts of vitamin D. These may include:

• UV-exposed raw Portobello mushrooms: These contain 568 IU per 50 g, which is 95% of a person's RDA
• UV-exposed raw white mushrooms: These contain 523 IU per 50 g, which is 87% of a person's RDA

Egg yolks

Egg yolks can also be high in vitamin D, especially if the chickens are free-range. For example, a dish of scrambled eggs using two large hen eggs contains 88 IU, which is 15% of a person's RDA.

Fortified foods

Manufacturers add vitamin D to many commercially available foods. People describe these foods as being fortified with vitamin D, or other nutrients. Common foods with extra vitamin D and other nutrients include:

• Cow's milk
• Orange juice
• Various breakfast cereals

Getting enough vitamin D

According to the ODS, if a person does not have enough vitamin D in their diet, they are at risk of developing weak bones. Symptoms of this might include pain in a person's bones or weakness in their muscles. These symptoms can be subtle initially. There is some research to suggest that vitamin D may contribute to other health benefits, such as:

• Resistance to some cancers
• Cardiovascular diseases
• Diabetes
• Hypertension
• Multiple sclerosis

However, according to the ODS, there is not yet enough evidence to know whether this is the case. Existing research has yielded mixed results. The RDA of vitamin D for all people aged 1–70 is 600 IU. For children below the age of 1, it is 400 IU, and for adults over 70, it is 800 IU. This assumes that a person has the minimum amount of direct sun exposure.

The general assumption is that a person who spends some time outside a few times per week will produce sufficient vitamin D. However, according to the ODS, this can vary considerably depending on:

• Season
• Time of day
• The presence of cloud cover or smog
• The color of a person's skin
• Whether a person is wearing sunscreen

Being in direct sunlight behind a window will not aid vitamin D production because glass cuts out the radiation that produces vitamin D.

Summary

Getting enough vitamin D is crucial to maintaining healthy bones. The easiest way of getting enough vitamin D is to regularly spend time outside, making sure that the arms, face, and legs have exposure.

Depending on a person's dietary preferences, consuming enough vitamin D may be difficult. In this case, vitamin D supplements, which are available to purchase online, may be a beneficial choice. However, if this is not possible, try to consume oily fish, some mushrooms, and free-range egg yolks.