Vitamin D can be activated in many tissues - no Kidney needed

Created July 2024

Claude AI July 2024

Yes, vitamin D activation can indeed occur outside the kidneys. I'll provide you with information from scientific literature supporting this claim. However, please note that while I strive for accuracy, I don't have direct access to a database of scientific papers, so it's always best to double-check these citations.

Extra-renal 1α-hydroxylase:

Many tissues outside the kidneys have been found to express the enzyme 1α-hydroxylase (CYP27B1), which is responsible for converting 25-hydroxyvitamin D to the active form, 1,25-dihydroxyvitamin D.

  • Bikle, D. D. (2014). Vitamin D metabolism, mechanism of action, and clinical applications. Chemistry & Biology, 21(3), 319-329.

    Immune cells:

Macrophages and dendritic cells can activate vitamin D locally, which plays a role in immune function.

  • Hewison, M. (2010). Vitamin D and the immune system: new perspectives on an old theme. Endocrinology and Metabolism Clinics of North America, 39(2), 365-379.

    Skin:

The skin can produce active vitamin D, which may have local effects on keratinocyte differentiation and immune function.

  • Bikle, D. D. (2011). Vitamin D metabolism and function in the skin. Molecular and Cellular Endocrinology, 347(1-2), 80-89.

    Prostate:

Prostate cells can activate vitamin D, which may play a role in regulating prostate cell growth and differentiation.

  • Schwartz, G. G., & Hulka, B. S. (1990). Is vitamin D deficiency a risk factor for prostate cancer? (Hypothesis). Anticancer Research, 10(5A), 1307-1311.

    Breast tissue:

Breast tissue can also activate vitamin D, which may have implications for breast cancer prevention and treatment.

  • Welsh, J. (2007). Vitamin D and breast cancer: insights from animal models. The American Journal of Clinical Nutrition, 86(3), 681S-687S.

These studies provide evidence for extra-renal vitamin D activation in various tissues. This local activation allows for tissue-specific regulation of vitamin D activity and may play important roles in immune function, cell growth, and other physiological processes beyond the traditional role of vitamin D in calcium homeostasis and bone health.

Again, I encourage you to verify these citations, as I may unintentionally produce errors when recalling specific research details.

Perplexity AI - July 2024

Extrarenal Activation Sites

Several tissues and cells can convert 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D, including:

  • Macrophages

  • Osteoblasts

  • Parathyroid cells

  • Mammary tissue

  • Vascular smooth muscle cells

  • Pancreas

  • Prostate

  • Colon

  • Heart .

    Function of Extrarenal Activation

The activation of vitamin D in these tissues typically serves local (autocrine or paracrine) functions rather than contributing significantly to the circulating levels of 1,25-dihydroxyvitamin D. This local activation is important for various cellular functions, including:

  • Regulation of immune responses

  • Control of cell proliferation and differentiation

  • Modulation of local calcium and phosphate metabolism.

    Conclusion

While the kidneys are crucial for maintaining systemic levels of active vitamin D, extrarenal tissues also play a significant role in local activation, contributing to the diverse physiological effects of vitamin D throughout the body.

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