What is Vitamin D?

Vitamin D is a fat-soluble vitamin that plays a vital role in maintaining calcium and phosphate levels in the blood, which are essential for keeping bones, teeth, and muscles healthy¹². It helps in the absorption of calcium, enhances bone growth, and is involved in immune function, reducing inflammation, and gene modulation³.

Sources of Vitamin D

There are three main ways to obtain Vitamin D:

1. Sunlight: The body synthesizes Vitamin D when the skin is exposed to UVB rays from sunlight⁴.
2. Diet: Only a few foods naturally contain Vitamin D, such as fatty fish (salmon, trout, tuna, and mackerel), beef liver, cheese, and egg yolks. Fortified foods, including milk, cereal, and yogurt, are also significant sources⁵⁶.
3. Supplements: Vitamin D supplements, available as D2 (ergocalciferol) and D3 (cholecalciferol), are common sources, especially for those with limited sun exposure or dietary intake⁷.

Recommended Intake

The Recommended Dietary Allowance (RDA) for Vitamin D varies by age and other factors:

• For most adults: 600 international units (IU) per day
• For adults over 70: 800 IU per day⁸⁹

It's important not to exceed the upper limit of intake, as very high levels of Vitamin D can lead to toxicity and other health issues²⁹.

Deficiency Risks and Symptoms

Vitamin D deficiency can lead to several health issues:

• Rickets: A condition in children that leads to soft and weak bones¹⁰.
• Osteomalacia: Softening of bones in adults¹⁰.
• Osteoporosis: A condition where bones become brittle and fragile⁷.

Other potential risks associated with low Vitamin D levels include an increased likelihood of fractures, higher susceptibility to infections, and possibly a contribution to chronic diseases such as cardiovascular disease and diabetes⁷⁶.

Vitamin D and Health Conditions

Emerging research links Vitamin D to a range of health conditions beyond bone health, including multiple sclerosis, rheumatoid arthritis, chronic pain, diabetes, high blood pressure, cardiovascular diseases, and certain cancers. However, more research is needed to confirm these associations⁹.

For more detailed information, you can refer to the Mayo Clinic and MedlinePlus.

Footnotes

1. Better Health Channel ↩

2. Mayo Clinic ↩ ↩²

3. NIH Office of Dietary Supplements ↩

4. Department of Health and Human Services ↩

5. NHS ↩

6. NCBI Bookshelf ↩ ↩²

7. MedlinePlus ↩ ↩² ↩³

8. Mayo Clinic ↩

9. Mayo Clinic News Network ↩ ↩² ↩³

10. StatPearls ↩ ↩²