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Vitamin D and its Role in Human Health
Table of Contents
Vitamin D is a fat-soluble vitamin essential for calcium and phosphate metabolism, bone health, muscle function, and immune system regulation. national institutes of Health - Vitamin D Fact Sheet
The human body can synthesize vitamin D when skin is exposed to ultraviolet B (UVB) radiation from sunlight. It is then stored in fat and muscle tissue,providing reserves for times with limited sun exposure. However, synthesis efficiency varies based on factors like skin pigmentation, latitude, time of day, and season.
for example, individuals with darker skin pigmentation require longer sun exposure to produce the same amount of vitamin D as those with lighter skin.National Center for Biotechnology Information – Vitamin D and Skin Pigmentation
Vitamin D Synthesis and sunlight Exposure
The human body produces vitamin D3 (cholecalciferol) in the skin when exposed to UVB radiation with a wavelength of 7-19 nm. American Academy of Dermatology – Vitamin D
The amount of vitamin D synthesized depends on several factors,including the intensity of sunlight,the duration of exposure,the amount of skin exposed,and the individual’s skin pigmentation. Latitude plays a significant role; locations further from the equator receive less UVB radiation, especially during winter months. Sunscreen use, while crucial for preventing skin cancer, also reduces vitamin D synthesis.
A study published in the Journal of the American Academy of Dermatology in 2017 found that regular sunscreen use can reduce vitamin D synthesis by up to 99%. pubmed – Effect of Sunscreen Use on Vitamin D Levels
dietary Sources and Supplementation
While sunlight is a primary source, vitamin D can also be obtained through diet and supplementation. Harvard T.H. Chan School of Public Health – Vitamin D
Few foods naturally contain significant amounts of vitamin D. Fatty fish (salmon, tuna, mackerel), beef liver, cheese, and egg yolks provide some vitamin D, but often insufficient to meet daily requirements. Many foods are now fortified with vitamin D, including milk, cereal, and orange juice. Supplementation is frequently enough recommended,notably for individuals at risk of deficiency.
The U.S. Preventive Services task Force (USPSTF) recommends that adults aged 65 years and older be screened for vitamin D deficiency. U.S. Preventive Services Task Force – Vitamin D Services for Older Adults
Vitamin D Deficiency and Health Implications
Vitamin D deficiency is defined as a serum 25-hydroxyvitamin D [25(OH)D] level less than 20 ng/mL (50 nmol/L). EndocrineWeb – Vitamin D Deficiency
Prolonged deficiency can lead to various health problems, including rickets in children (softening of the bones) and osteomalacia in adults (bone pain and muscle weakness). It has also been linked to an increased risk of osteoporosis, falls, fractures, cardiovascular disease, autoimmune diseases, and certain types of cancer, although the evidence for thes associations is still evolving.
according to the Centers for Disease Control and Prevention (CDC), approximately 32% of adults in the United States are deficient in vitamin D.Centers for Disease control and Prevention - vitamin D status (Data as of 2023-2024)
Breaking News Check (as of 2026/01/27 07:17:12)
As of January 27, 2026, there are no major breaking news events substantially altering the established understanding of Vitamin D’s role in health. Ongoing research continues to refine recommendations regarding optimal levels and the link between Vitamin D and various health outcomes, but no paradigm shifts have occurred. ClinicalTrials.gov (search for “Vitamin D” to view ongoing studies)
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