Vitamin D plays a vital role in maintaining overall health, with impacts ranging from bone health to immune function.
Vitamin D graphic

Vitamin D is often referred to as the “sunshine vitamin.” It is a vital fat-soluble nutrient that plays a significant role in maintaining overall health and well-being. It is unique among vitamins because it can be synthesized by the body when the skin is exposed to sunlight.

What is vitamin D?

Vitamin D actually refers to a group of fat-soluble secosteroids, the most important of which are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2 is primarily obtained from plant sources and fortified foods, while vitamin D3 can be synthesized in the skin when we are exposed to ultraviolet B (UVB) radiation from sunlight. Vitamin D3 is the form we are focusing on here.

Its primary functions include:

  • Calcium absorption: essential for maintaining strong bones and teeth.
  • Bone health: regulates bone mineralization and helps prevent conditions like osteoporosis and rickets.
  • Immune function: plays a role in reducing the risk of infections and autoimmune diseases.
  • Cell growth and differentiation: helps prevent abnormal cell growth.

Deficiency can contribute to muscle weakness and pain, increasing the risk of falls and fractures. Low vitamin D levels have also been associated with an increased risk of chronic diseases like cardiovascular diseases, diabetes, autoimmune disorders, and certain types of cancers. Studies have also suggested a link between low vitamin D levels and mood disorders like depression and seasonal affective disorder (SAD).

How to get enough vitamin D

First, it’s important to get your blood tested to determine your existing vitamin D levels. That way you’ll know whether you need to supplement and by how much. Vitamin D 25-Hydroxy is the most accurate measure of your vitamin D status, with an optimum measurement considered to be above 50 ng/mL.

The most natural source of vitamin D is sunlight, so spending time (10-30 minutes) in the sun without sunscreen can help the skin synthesize vitamin D. For a number of reasons, however, this may not always be possible or advisable.

Supplements are the most commonly used way to ensure you get an adequate intake of vitamin D. This is especially true if you live in an area where sunlight is limited some or most of the year. If your blood levels are unknown, start by taking 5000 IU of vitamin D3 per day. This is best taken along with 100 mcg of vitamin K2 daily (or 800 mcg every week). If you take more than 8000 IU of vitamin D a day, you should also include 250-500 mg of magnesium per day.

Some foods — like fatty fish (salmon, sardines, tuna), egg yolks, shrimp, mushrooms, milk, kefir, and cheese — contain vitamin D, but this is not the ideal way to supplement. For example, a 3.5-ounce portion of salmon contains the equivalent of about 400 IU of vitamin D. You would need to eat 12.5 portions to get 5000 IU of vitamin D3!

Factors affecting vitamin D levels
  • Sunlight exposure: The amount of sun exposure, time of day, season, and latitude play a crucial role in vitamin D synthesis.
  • Skin tone: Darker skin tones have more melanin, which reduces the skin’s ability to produce vitamin D from sunlight.
  • Age: The skin’s ability to synthesize vitamin D decreases with age.
  • Geographic location: People living in higher latitudes with less sunlight are more prone to defic