Views: 1 Author: Site Editor Publish Time: 2022-07-22 Origin: Site
Reproductive tissues and mammalian embryogenesis depend on rar for gene regulation. Vitamin A plays an extremely important role in these tissues through related ways. These effects are also achieved through the regulation of cell proliferation and differentiation, especially in endochondral osteogenesis. When vitamin A is deficient, long bone formation and tooth development are impaired; Male testicles atrophy, the number of sperm decreased, decreased vitality.
Antagonism of vitamin A and vitamin D activity and its effect on bone metabolism
At present, many research results show that there is a close relationship between vitamin A and bone metabolism. Vitamin A deficiency can reduce the number of osteoclasts and control the function of osteoblasts, resulting in excessive periosteal bone hyperplasia and smaller bone cavities. The adverse effects of excessive vitamin A on bone mineralization and structural integrity have become a recent concern. Excessive vitamin A can stimulate bone resorption and inhibit bone regeneration. This effect may have a common mechanism with hypercalcemia in chronic vitamin A poisoning. Considering that vitamin A and vitamin D are widely involved in the regulation of nuclear receptors in many cells, the effect of vitamin A deficiency and excess on bone metabolism may be related to its antagonism to vitamin D activity.
In addition to affecting normal health-related evolutionary functions, vitamin A also has a regulatory role in correcting a variety of pathological states. Vitamin A and its isomers can promote terminal differentiation, inhibit proliferation and promote apoptosis, which plays a role in the tumor in the process of tissue malignant transformation. Studies on various cancer cell lines in vitro have found that large doses of retinoids have anti-cancer ability.
Vitamin A promotes the production of hemoglobin and increases the intake of iron in food
Early studies found that vitamin A intervention experiments can increase hemoglobin and blood cell counts in people with multi nutrient deficiency anemia. Vitamin A and Pro Vitamin A may improve iron absorption by blocking the interference of phytic acid. The study found that the effect of vitamin a nutritional status on the blood system is not only the direct effect of dietary vitamin A on promoting iron absorption, but also a certain regulatory effect on iron nutritional status, including stimulating hematopoietic mother cells, promoting anti infection, and mobilizing iron into the red blood cell line. From the early embryonic yolk sac stage, to the intrauterine fetal liver formation stage, and then to the bone marrow formation stage, there are relevant documents proving the existence of retinoids regulating hematopoiesis. Vitamin A status not only affects the proliferation of bone marrow hematopoietic cell lines, but also affects platelet formation and thrombosis.
Vitamin A is mainly used to prevent and treat night blindness and dry eye disease, as well as local suppurative infection of skin after burns. Vitamin A intake of human body should not exceed 3mg/ day for adults and 2mg/ day for children. If you take a large dose of vitamin A, because the excretion ratio is not high, you will have acute hyperactivity of vitamin A. the main symptoms are short-term hydrocephalus and vomiting, and some may have headache, sleepiness, nausea and other symptoms . After taking large doses of vitamin A for a long time, children will have symptoms of excessive vitamin A, mainly hepatosplenomegaly, reduction of red blood cells and white blood cells, rapid growth of bone marrow, brittle long bones, and prone to fractures. A new Swedish study shows that middle-aged men with high levels of vitamin A in their blood have a much higher probability of fracture in their old age than those with low levels of vitamin A in their blood. Therefore, vitamin A is indispensable to the human body and cannot be abused. As long as you ensure that your diet is rich in vitamin A or carotene, you can effectively prevent vitamin A deficiency without taking additional vitamin A supplements.