Contrary to popular belief, vitamin D is technically not a vitamin. Strictly speaking, vitamin D is a prohormone produced by the liver and pancreas.

Vitamin D has various forms including calcitriol, ergocalciferol, calcidiol and cholecalciferol.

However, only calcidiol and cholecalciferol are produced by the body. Calcitriol is a synthetic version of cholecalciferol that physicians use to treat severe vitamin D deficiencies, while ergocalciferol is a supplemental form of vitamin D.

When the sun’s rays hit skin cells, the pancreas converts a molecule known as 7-dehydrocholesterol into cholecalciferol. A similar process occurs in the liver to produce calcidiol, but this form of vitamin D is not as potent as cholecalciferol.

Various factors influence the amount of vitamin D that the body produces. For instance, high melanin levels in the skin can inhibit the production of vitamin D. Meanwhile, strong ultraviolet (UV) rays can lead to cellular damage and skin cancer instead of vitamin D production.

The important role of vitamin D

Vitamin D plays various critical functions throughout the body. For instance, vitamin D increases the body’s absorption of calcium, an essential component of bones and teeth. Moreover, adequate vitamin D intake boosts the immune system, regulates blood pressure and supports cardiovascular health.

Vitamin D also prevents a host of deficiency-related conditions including heart disease, Type 2 diabetes, autoimmune diseases and bone disorders.

However, age and underlying conditions can greatly slow down the production of vitamin D. Signs and symptoms of vitamin D deficiency include fatigue, joint pain and muscle aches.

Food sources of vitamin D

Fortunately, vitamin D can be found in various foods, such as:

Fish

Fatty fishes contain high amounts of vitamin D. For instance, a 3.5 ounce (oz) of canned salmon provides up to 386 international units (IU) of vitamin D. Similarly, a can of sardines can contain up to 70 percent of the recommended dietary intake of vitamin D, while a 3 oz serving of mackerel provides 547 IU of vitamin D. Meanwhile, the freshwater eel delivers a staggering 792 IU of vitamin D.

Egg yolks

Egg yolks are excellent sources of protein and vitamin D. On average, an egg contains 41 IU of vitamin D. But vitamin D content may vary depending on the type of egg. For instance, pastured eggs, or eggs produced by free-range hens, can have four to six times as much vitamin D as supermarket eggs.

Mushrooms

Mushrooms that have been regularly exposed to sunlight also contain high levels of vitamin D. This is due to the fact that mushrooms can also synthesize vitamin D upon exposure to UV rays, much like humans. Additionally, clinical trials have demonstrated that the amount of vitamin D in certain types of mushrooms can be increased significantly by momentarily exposing the mushrooms to UV rays. Mushrooms that contain vitamin D include shiitake mushrooms, portobello mushrooms and button mushrooms.

Plain yogurt

Plain yogurt made from raw, unpasteurized milk is an excellent source of vitamin D. A 6 oz serving of plain yogurt contains anywhere between 80 to 100 IU of vitamin D.

Whole grain oats

Whole grain oats are also fortified with vitamin D. Half a cup of whole grain oats can provide anywhere between 54 to 136 IUs of vitamin D. Whole grain oats also contain essential nutrients, vitamins and minerals that also boost various body functions including immunity, bone development and blood pressure control, much like vitamin D.

Nothing beats spending a few minutes under the sun for your daily dose of vitamin D. But it sure doesn’t hurt to eat plenty of vitamin D-rich foods to supplement this effort.

Sources:

MedicalNewsToday.com

Prevention.com