Vitamin D is a crucial nutrient and hormone that plays several important roles in our body. Here are some key points about its benefits and functions:

1. Bone Health: Vitamin D helps in the absorption of calcium, which is essential for maintaining strong bones. It prevents conditions like rickets in children and osteomalacia in adults¹². Adequate vitamin D levels also help protect older adults from osteoporosis³.

2. Muscle Function: Vitamin D is necessary for muscles to function properly. It reduces inflammation and helps in neuromuscular function³⁴.

3. Immune System Support: Vitamin D supports the immune system by enhancing pathogen-fighting effects of monocytes and macrophages—white blood cells that are important parts of your immune defense—and decreases inflammation⁵.

4. Potential Disease Prevention: Studies suggest that vitamin D might play a role in reducing the risk of chronic diseases such as cardiovascular diseases, cancer, and multiple sclerosis. However, more research is needed to establish these connections definitively⁶⁷.

5. Sources:

   • Sunlight: The most significant source of vitamin D is sunlight. The skin synthesizes vitamin D when exposed to UVB rays from the sun⁴.
   • Diet: Few foods naturally contain vitamin D. Fatty fish like salmon, mackerel, and sardines, as well as fish liver oils, are among the best sources. Small amounts of vitamin D are also found in beef liver, cheese, and egg yolks⁸.
   • Fortified Foods and Supplements: Many foods such as milk, cereal, and orange juice are fortified with vitamin D. Supplements are also widely used to ensure adequate intake⁹.

Recommended Intake

• Infants (0-12 months): 400 IU (International Units) daily.
• Children (1-18 years): 600 IU daily.
• Adults (19-70 years): 600-800 IU daily.
• Older Adults (71 years and older): 800 IU daily¹.

Risks of Deficiency

Insufficient vitamin D can lead to bone deformities in children and weak bones in adults. People at risk of deficiency include those with limited sun exposure, individuals with darker skin, older adults, and those with specific health conditions¹¹⁰.

Safe Upper Limits

It is important not to exceed safe limits for vitamin D intake, as excessive amounts can cause toxicity and lead to conditions like hypercalcemia. The generally accepted upper limit for adults is 4000 IU per day¹².

Footnotes

1. MedlinePlus ↩ ↩² ↩³ ↩⁴

2. NHS ↩ ↩²

3. Office of Dietary Supplements ↩ ↩²

4. Better Health Channel ↩ ↩²

5. NIH - Calcium and Vitamin D: Skeletal and Extraskeletal Health ↩

6. Natasha Khazai, National Center for Biotechnology Information ↩

7. Harvard T.H. Chan School of Public Health ↩

8. Harvard T.H. Chan School of Public Health - Sources of Vitamin D ↩

9. Mayo Clinic ↩

10. NIH - National Center for Biotechnology Information ↩