Overview of Lipid-Soluble Vitamins
Definition: Vitamins that dissolve in fats and oils and are stored in the body's fatty tissue and liver.
Key Vitamins: A, D, E, K.
Vitamin A
Forms: Retinol, retinal, retinoic acid, and provitamin A carotenoids (e.g., beta-carotene).
Metabolic Roles: Vision: Retinal combines with opsin to form rhodopsin in the retina, crucial for low-light and colour vision.
- Gene Expression: Retinoic acid regulates gene transcription by activating nuclear receptors.
- Cell Differentiation: Essential for the differentiation of epithelial cells and immune function.
- Growth and Development: Critical for embryonic development and growth.
Vitamin D
Forms: Vitamin D2 (ergocalciferol) and D3 (cholecalciferol).
Metabolic Roles: Calcium Homeostasis: Enhances intestinal absorption of calcium and phosphate, crucial for bone health.
- Bone Health: Promotes bone mineralization and remodelling.
- Immune Function: Modulates the immune system, reducing inflammation.
- Cell Growth and Differentiation: Influences the growth and differentiation of various cell types.
Vitamin E
Forms: Tocopherols and tocotrienols, with alpha-tocopherol being the most active form.
Metabolic Roles: Antioxidant: Protects cell membranes from oxidative damage by neutralizing free radicals.
- Immune Function: Enhances immune response by protecting immune cells from oxidative stress.
- Cell Signalling: Involved in cellular signaling processes, influencing gene expression and cell proliferation.