Vitamin D: Functions Beyond Classical Calcium/Phosphate Regulation, Slides of Materials science

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Recent Vitamin D Research Focusing

on its Functions Beyond Classical

Calcium/Phosphate Regulation

Supervised by

Prof. Declan Gilheany

CONTENTS Types and Sources of Vitamin D Vitamin D Production, Metabolism and Mechanism of Action Role of Vitamin D supplements in averting Cancer and Cardiovascular disease (CVD) Relationship Between Vitamin D and Cognitive Decline in Older Individuals Conclusion References Functions of Vitamin D

Vitamin D Metabolic Pathway in Humans

7-dehydrocholesterol undergoes either enzymatic conversion to cholesterol or photolysis to produce vitamin D. Sun-dependent reactions in the skin create pre-vitamin D 3 through UV light (290-315nm), highlighting the importance of sunlight, followed by heat-dependent conversion into inactive vitamin D. Sunlight and Heat - Dependent Reactions (image from cataylst university) (Inactive vitamin D)

Liver and Kidney Conversion

Vitamin D Metabolic Pathway in

Humans

Cholecalciferol undergoes a series of enzymatic modifications in the liver and kidneys. Initially, it forms 25-hydroxycholecalciferol in the liver, and then, through the action of 1-hydroxylase in the kidneys, it is converted into the active form, 1,25-dihydroxycholecalciferol (image from cataylst university)

Functions of Vitamin D

Cassical and Non-Classical Function [2] Vitamin D has classical and non-classical biological functions, as shown in the figure below. [2]

Non-Classical Role of Vitamin D supplements in averting Cancer and Cardiovascular disease (CVD)

• A New England study investigated the effects of 2000 IU vitamin D supplementation on cancer and cardiovascular disease in 25,000+ participants aged 50 or older. After 5.3 years, no significant differences in overall cancer incidence were found across treatment arms.[3]
• However, an Italian subgroup focused on BMI, finding that Vitamin D's efficacy in cancer treatment is influenced by body weight. As Vitamin D is fat-soluble, its effectiveness depends on the body's fat content. [4]
• Upon reevaluation, the New England writers noted a significant decrease in advanced cancers among participants receiving Vitamin D compared to a placebo. Stratifying by BMI, a notable reduction (24%) in metastatic or fatal cancer occurred in the vitamin D group for individuals with a normal BMI (BMI < 25), but this effect was absent in those with overweight or obesity. [5] Vitamin D and Cancer Cure Decrease in effectiveness of Vitamin D supplement (image from Adobe stoc

Relationship

Between Vitamin

D and Cognitive

Decline in Older

Individuals

• (^) A research involving 858 elderly subjects investigated the correlation between vitamin D deficiency and cognitive function, using the Mini-Mental State Examination (MMSE) for assessment. Participants with severely deficient levels of serum 25(OH)D (25 nmol/L) had a 1.60 times higher relative risk (95% CI, 1.19-2.00) of substantial cognitive decline on the MMSE compared to those with sufficient levels of 25(OH)D (75 nmol/L). [8]
• The results indicated that individuals with vitamin D levels below 50nmol/L, classified as deficient, had a significantly higher likelihood of cognitive decline, suggesting a potential link to early dementia. Notably, the study challenged conventional norms by considering vitamin D levels between 50nmol/L and 75nmol/L as insufficient, emphasizing the importance of maintaining optimal levels (75nmol/L) Vitamin D and Cognitve Function Cognitive function variations in 858 elderly individuals in relation to serum 25(OH)D [8]

Conclusion

Ongoing research indicates vitamin D's potential health roles, but findings are inconsistent. Its complex link to health involves genetics, lifestyle, and the environment. individual should consult healthcare professionals for personalized guidance.

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