Vitamin D is a fat-soluble vitamin that is critical for maintaining healthy bones and teeth, supporting the immune system, brain, and nervous system¹. It enhances the absorption of calcium and phosphorus from the gut, which is necessary for bone mineralization². A deficiency in vitamin D can lead to conditions such as rickets in children and osteomalacia or osteoporosis in adults³.

There are two main forms of vitamin D found in supplements and foods:

1. Vitamin D2 (Ergocalciferol): This form is typically obtained from plant sources and fortified foods⁴.
2. Vitamin D3 (Cholecalciferol): This form is synthesized by the body when the skin is exposed to sunlight and is also found in animal-based foods and some supplements⁴.

While sunlight is a primary source of vitamin D for most individuals, it can also be obtained from dietary sources such as fatty fish, liver, egg yolks, and fortified foods like milk and cereals⁵.

Functions and Benefits

• Bone Health: Vitamin D plays a crucial role in calcium absorption and bone health⁶.
• Immune Support: It helps modulate the immune system and has been linked to a reduction in the risk of infections⁷.
• Muscle Function: Necessary for proper muscle function⁸.

Sources of Vitamin D

• Sunlight: The skin produces vitamin D when exposed to UVB rays from the sun⁹.
• Food: Natural sources include fish (salmon, mackerel), beef liver, cheese, and egg yolks. Many countries also fortify dairy products and cereals with vitamin D¹⁰.
• Supplements: Available in the forms of D2 and D3, often recommended for individuals at risk of deficiency¹¹.

Recommended Dosages

The recommended intake of vitamin D varies by age, sex, and life stage, but generally, the diet alone does not provide adequate amounts of vitamin D¹². Supplements can help achieve the necessary levels.

Keep in mind that excessive intake of vitamin D can lead to toxicity, resulting in high blood calcium levels which could cause various health issues¹³.

Footnotes

1. Mayo Clinic ↩

2. MedlinePlus ↩

3. MedlinePlus ↩

4. Harvard T.H. Chan School of Public Health ↩ ↩²

5. MedlinePlus ↩

6. Office of Dietary Supplements - NIH ↩

7. MedlinePlus ↩

8. MedlinePlus ↩

9. NHS ↩

10. NHANES - Nutritional Health ↩

11. Better Health Channel ↩

12. Mayo Clinic ↩

13. Mayo Clinic ↩