FOOD20003 Lecture Notes - Lecture 31: Retinol Binding Protein, Hemolysis, Spinach
28 Jun 2018
School
Department
Course
Professor
The Fat-Soluble Vitamins: A, D, K, E
Vitamin A
• Retinol – reproduction
• Retinal – vision
• Retinoic acid – regulates growth
• Carotenoids – provitamin A that can be converted to the vitamin in the body
• Storage and transformation occurs in the liver
• Vision – converts light energy into nerve impulses at the retina
o Opsins + retinal = rhodopsin
• Protein synthesis and cell differentiation
o Through cell differentiation, vitamin A allows cells to perform specific
functions
o Integrity of cornea & epithelial cells
• Reproduction and growth
o Sperm development in men, normal foetal development in women
o Growth in children
o Remodelling of the bone involves osteoclasts, osteoblasts and
lysosomes
§ Osteoclasts: destroy bones
§ Osteoblasts: build ones
§ Lysosomes = degradative enzymes
• Beta-carotene as antioxidant
• Deficiency – hypovitaminosis A
o As it is stored in the liver, takes approx. 1 year to develop symptoms
o Impaired immunity
o Night blindness à inability to see in dim lights
o Blindness: xerosis à xerophthalmia à keratomalacia
o Keratinisation – dry & scaly skin
• Toxicity – hypervitaminosis A
o Occur with preformed vitamin A in animal foods, fortified foods but
mainly due to supplements
o Bone defects à increased activity of osteoclasts causes weakened
bonds (osteoporosis)
o Can also lead to birth defects
