What Is Vitamin D? How Much You Need, Sources and More

Calcium is recognized as an essential bone-building mineral, but very few people understand the importance of vitamin D for skeletal health.

Without vitamin D, your body will not be able to absorb and metabolize calcium adequately, often leading to osteoporosis. Vitamin D also plays a critical role in muscle function, immunity, and the transmission of neural messages between the brain and body.

Normal Levels of Vitamin D That Should Be Present in the Body

The normal range for vitamin D is above 20 ng/ml, although the International Osteoporosis Foundation recommends a minimum level of 30 ng/ml. (1)

There is concern that levels above 50 ng/ml increase the risk of fractures, although the data come from a small number of studies. (2)(3)

Remember that it takes a long time for vitamin D levels to go up in the body as it is a fat-soluble vitamin. Testing more than once a year is typically not recommended.

Types of Vitamin D

Depending upon its source, vitamin D can be classified into two major forms:

• Vitamin D2 – derived from external sources such as vegetables and supplements
• Vitamin D3 – formed in the body upon exposure to UVB radiations

Because sun exposure is a major prerequisite for meeting most of your vitamin D needs, this vital nutrient is also referred to as the “sunshine vitamin.” One common feature of both these forms of vitamin D is they do not become active until they pass through the liver.

Common Symptoms of Vitamin D Deficiency

Most of the people who are vitamin D deficient are asymptomatic (do not have symptoms). However, when the level of this vitamin drops very low, some people may experience fatigue, weakness, and muscle spasms.

Some observational studies also found an association between low vitamin D levels and feeling sad in winter times. (4)

At the cellular level, vitamin D deficiency can cause decreased calcium absorption, resulting in thinning of bones in the long run. This can lead to rickets in children and osteomalacia in adults. Both of these diseases are not common in developed countries.

Treatment for Vitamin D Deficiency

Vitamin D deficiency is typically treated with supplements since the amount of vitamin D found in food sources is not enough. The prescribed dosage will vary depending upon the patients’ blood levels of vitamin D.

Until very recently, the recommendation was to supplement with high-dose vitamin D if your level was less than 20 ng/mL. (5) However, this recommendation changed and now a daily dose of a small amount ranging from 3000 to 5000 IU is recommended. (5)

Ways to Increase the Levels of Vitamin D in the Body

The following tips may be helpful in increasing your vitamin D levels:

1. Sunlight exposure

Fifteen minutes of sunlight exposure on the arms and legs without sunscreen helps improve the levels. When exposed to UVB radiation from sunlight, your skin converts the vitamin D precursor (a form of cholesterol) to vitamin D.

The color of the skin does impact the formation of vitamin D. Dark-skinned people, due to high amounts of melanin, tend to have lower vitamin D levels than fair-skinned people.

2. Diet

Consuming vitamin D-rich foods, such as salmon, egg yolks, mushrooms, sardines, mackerel, herring, red meat, breakfast cereals, liver, and fat spreads, may help.

3. Supplements

As discussed above, vitamin D can be taken in the form of dietary supplements. Vitamin D can be taken at any time with or without food. Consult your doctor about its use and recommended levels.

Risk Factors for Vitamin D Deficiency

Certain people are at a higher risk of vitamin D deficiency, including those who are:

Does Vitamin D Boost Energy and Improve Metabolism?

Vitamin D deficiency is linked to fatigue, which has been shown to improve with vitamin D supplementation. No correlation between vitamin D and metabolism/BMR has been found.

A few studies, however, found that vitamin D plays a role in inflammation and insulin sensitivity, but the results were not clear on the vitamin’s impact on metabolism. (8)(9)

Does Vitamin D Increase Estrogen in Women and Progesterone in Men?

No, vitamin D is considered a hormone, but no impact has been seen on estrogen and progesterone.

Does Vitamin D Help in Breast Growth?

No, vitamin D has not been shown to have any effect on breast growth.

Can a Low Level of Vitamin D Be a Sign of Cancer?

A low level of vitamin D is not a sign of cancer. Still, cross-sectional studies found an association between low vitamin D levels and certain cancers, especially gastrointestinal-related cancers. More studies are needed on this topic. (10)(11)

Moreover, people who have cancer tend to have worse outcomes if they are low on vitamin D.

Final Word

Vitamin D deficiency is very common, particularly in dark-skinned people and those who spend most of their time indoors.

Low levels of vitamin D have been associated with increased risk of cardiovascular disease, hypertension, certain cancers including gastrointestinal cancers, and autoimmune diseases. People who are at high risk for vitamin D deficiency should be tested and take a replacement supplement based on their levels.