Again - shared from writings of Linda Hornberger -
5. Vitamins (2 of 6)
The first vitamin we will look at is Vitamin A. Vitamin A is actually several compounds, retinol, retinal, and retinoic acid, with retinol being the most biologically active form. In the body, vitamin A is involved in vision, bone growth, reproduction and epithelial tissue (the tissue that lines body cavity, organs, and comprises much of the glands).
Regarding vision, the retinal combines with a protein to form rhodopsin, which is the light-sensitive pigment found in the rods of the retina. [Rods are the part of the retina which is responsible for low-light, black and white vision.] The rhodopsin splits apart when exposed to light, releasing energy that is transmitted by the nerves. It then regenerates in the dark. With a deficiency of vitamin A, the rods become increasingly insensitive to light, eventually leading to night blindness.
5. Vitamins (2 of 6)
The first vitamin we will look at is Vitamin A. Vitamin A is actually several compounds, retinol, retinal, and retinoic acid, with retinol being the most biologically active form. In the body, vitamin A is involved in vision, bone growth, reproduction and epithelial tissue (the tissue that lines body cavity, organs, and comprises much of the glands).
Regarding vision, the retinal combines with a protein to form rhodopsin, which is the light-sensitive pigment found in the rods of the retina. [Rods are the part of the retina which is responsible for low-light, black and white vision.] The rhodopsin splits apart when exposed to light, releasing energy that is transmitted by the nerves. It then regenerates in the dark. With a deficiency of vitamin A, the rods become increasingly insensitive to light, eventually leading to night blindness.
Regarding epithelial tissue, vitamin A is necessary for the production
and differentiation of the cells and for the production of mucoproteins,
found in some of the mucous secreted by the body. This mucous, in the
respiratory and gastrointestinal tract is an barrier against infection.
With a deficiency of vitamin A, lesions occur which can then lead to
increased infections.
Regarding bone and tooth development, vitamin A is important for the epithelial cartilage and for osteoclast activity, which are the cells responsible directly for bone growth.
Regarding reproduction, vitamin A has been shown to be important for the production of sperm and for normal estrous cycles.
In most animal, vitamin A is converted from carotenoids, the yellow orange pigments in plants. Cats, however, lack the enzyme (or are very deficient in it) which converts the carotenoids. Thus, cats MUST consume vitamin A. Fish oils, milk, liver, and egg yolk are all sources for pre-formed vitamin A which cats can use.
Interestingly, lutein, one of the carotenoids, and beta-carotene do actually have a role in cats. It seems these two compounds have a function in cell-mediated and humoral immune response. [Regarding this, see https://www.ncbi.nlm.nih.gov/pubmed/10713345 " Compared to control, cats fed lutein also showed enhanced Con A- and pokeweed mitogen-stimulated PBMCs proliferation. Dietary lutein also increased the percentages of CD4+ and CD21+ lymphocytes on Week 12 but had no significant effect on pan T, CD8 and MHC class II markers. Plasma IgG was higher (p<0 .05="" 10mg="" 12.="" 8="" action="" and="" cats.="" cats="" domestic="" fed="" immuno-modulatory="" in="" lutein="" of="" on="" p="" results="" support="" the="" these="" weeks=""> Note: not my cat
Regarding bone and tooth development, vitamin A is important for the epithelial cartilage and for osteoclast activity, which are the cells responsible directly for bone growth.
Regarding reproduction, vitamin A has been shown to be important for the production of sperm and for normal estrous cycles.
In most animal, vitamin A is converted from carotenoids, the yellow orange pigments in plants. Cats, however, lack the enzyme (or are very deficient in it) which converts the carotenoids. Thus, cats MUST consume vitamin A. Fish oils, milk, liver, and egg yolk are all sources for pre-formed vitamin A which cats can use.
Interestingly, lutein, one of the carotenoids, and beta-carotene do actually have a role in cats. It seems these two compounds have a function in cell-mediated and humoral immune response. [Regarding this, see https://www.ncbi.nlm.nih.gov/pubmed/10713345 " Compared to control, cats fed lutein also showed enhanced Con A- and pokeweed mitogen-stimulated PBMCs proliferation. Dietary lutein also increased the percentages of CD4+ and CD21+ lymphocytes on Week 12 but had no significant effect on pan T, CD8 and MHC class II markers. Plasma IgG was higher (p<0 .05="" 10mg="" 12.="" 8="" action="" and="" cats.="" cats="" domestic="" fed="" immuno-modulatory="" in="" lutein="" of="" on="" p="" results="" support="" the="" these="" weeks=""> Note: not my cat
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