seminar presentation of vitamin D3

1. AL-Nahrain University
College Of Medicine
Department of
Clinical Biochemistry
M.Sc student
Khalid Jamal Hadi
Supervisor
M . Hend Ahmed Abass

2. Introduction
Vitamin D3 is fat soluble vitamin derivative from
cholesterol act as steroid hormone
its present in skin as (7-dehydocholseterol)
inactive form when human exposed to sunlight
its convert to Chalseferol Vit D3
derivative form plant as Ergocalciferol vit D2
and derivative from animal source as
Chalseferol Vit D3

4. Theactiveform

5. Mechanism of action of Vitamin D
Binding of 1,25(OH)2D3 to vitamin D
receptpr (VDR), which is principally
located in the nuclei of target cells
 Act as a transcription factor that
modulates the gene expression of
transport proteins (such as TRV6 and
calbindin), which are involved in calcium
absorption in the intestine

6. Mechanism of action of Vitamin D
VDRs expressed by cells in most organs,
including the brain, heart, skin, gonads,
prostate, breast.
 VDR activation in the intestine, bone,
kidney, and parathyroid gland cells leads to
the maintenance of calcium and
phosphorus levels in the blood and proper
maintenance of bone architecture.

7. Mechanism of action of Vitamin D

8. Intestinalabsorptionand transport
 Vitamin D is incorporated into chylomicrons, when
released, the chylomicrons convey the vitamin in the
mesentericlymph to the systemic circulation.
 In the lymph, an appreciable amount of the vitamin
D in the chylomicrons is transferred to the vit
DBP.
 After lipolysis of the chylomicrons, the vitamin D
remaining on the chylomicron remnants, and also
the vitamin D bound to protein, is initially taken up
by the liver.

9. Causes of VDD
The main risk factors for VDD in hot area
 Inadequate exposure to sun
– Indoor confinement during the day,
– Living in urban areas with tall buildings
around
– Clothing pattern
 Atmospheric pollution

10. Causes of VDD
 Darker skin pigmentation,
 Low physical activity
 Malabsorption
 Some diseases
• Liver failure
• Chronic renal disease

11. Dietary requirement
 The dietary requirement for vitamin D depends
upon the amount of vitamin synthesized by
solar irradiation of the skin.
 Exposing hands, arms and face on a clear
summer day for 10–15 min, two to three times
a week, should yield sufficient cutaneous
production of vitamin Dto meet daily needs.
 Tomaintain satisfactory plasma 25(OH)D levels
without any input from skin irradiation, an oral
input in the region of 10–15 μg of vitamin D
per day would be required.

12. The recommended dietary dose for
VIT D intake

13. Normal values

14. Associated Risk Factors
 Use of sunscreen creams/lotions,
 Low intake of Vitamin D rich foods,
 Low calcium intake,
 High fiber diet,
 Exclusive Breastfeeding,
 Some medications and
 Some genetic factors

15. VitaminD-related diseases
• Rickets
 Theclassicvitamin Ddeficiency
diseaseinchildren.
 The disease is characterized by
bow legs or knocks knees,
curvature of the spine, and
pelvic and thoracic bone
deformities.
 Thesedeformities result from the
mechanical stresses of body
weight and muscular activity
applied to the soft un calcified
bone.

16. VitaminD-related diseases
• Osteomalacia
 In adults, when the skeleton is fully
developed, vitamin D is still
necessary for the continuous re
modelling of bone.
 During prolonged vitamin D
deficiency, the newly formed, un
calcified bone tissue gradually
takes the place of the older bone
tissue and the weakened bone
structure is easily prone to
fracture.

17. VDD and Type 2 Diabetes
 Altered vitamin D and calcium homeostasis - type 2
diabetes
 Low serum levels of 25(OH)D are associated with
impaired pancreatic β cell function and insulin
resistance
 Cod liver studies also show significant reduction of
incidence of Type I DM
 Insulin secretion-Ca dependent

18. • Vitamin D deficiency during pregnancy is associated
with the non-
classical actions of this hormone.
• VDD is associated with
• Preeclampsia
• Insulin resistance & gestational diabetes mellitus
• Immune modulation
• Preterm delivery
• LBW
• An increased risk for caesarean section delivery
• Impaired neonatal immunity

19. Refrance
• Zempleni J, Rucker RB, McCormick DB, and Suttie JW (2007) Handbook of
VITAMINS. Fourth Edition. Taylor & Francis Group.
• Holick MF (2003) Vitamin D: a millenium perspective. J Cell Biochem 88:296–
307
• Bender D (2018). Nutritional Biochemistry of the Vitamins. Second
Edition. Cambridge University Press.
• lippincotts-biochemistry-6th-edition
• The American Journal of Clinical Nutrition, Volume 85, Issue 3, 1
March 2007, Pages 788–795, https://doi.org/10.1093/ajcn/85.3.788

20. Thank you