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Vitamin A is a fat soluble vitamin. It has many physiological functions such as promoting growth and reproduction, maintaining normal secretion of bone, epithelial tissue, vision and mucosal epithelium. Vitamin A and its analogues can prevent precancerous lesions. When lacking, it is characterized by growth retardation and decreased dark adaptation ability, resulting in night blindness.
Vitamin A is mainly used to prevent and treat night blindness, dry eye disease, and local purulent infection of skin after burn.
Vitamin A is found in humans, various mammals, birds and fish. Beef liver and sheep liver are the highest, with 20000 retinol equivalent per 100g; Secondly, chicken liver is about 10000; Goose, pig and duck livers are also between 4000 and 6000. The yolks of all kinds of eggs are also rich in vitamin A about 1000. Plants do not contain vitamin A, but contain a nutrient called carotene, which can be converted into vitamin A in humans and animals, so carotene is also called provitamin A or provitamin A. Carrots, broccoli and wolfberry are rich in carotene, which is about 1500 retinol equivalent per 100g. In daily life, we can easily distinguish the amount of vitamin A from the color. In general, when the yellow and green color of vegetables and fruits is darker, the content of carotene is higher. Many vegetables and fruits, such as carrots, sweet potatoes, zucchini, pumpkins, corn, apricots, peaches and persimmons, are orange because of their rich carotene content. Green leafy vegetables, especially dark green vegetables, are also very rich in carotene, but their original yellow color is covered by chlorophyll (green).
Deficiency of vitamin A or carotene in the diet or malabsorption may cause vitamin A deficiency. The clinical symptoms are mainly in the eyes and skin.
Night blindness is one of the early symptoms of human vitamin A deficiency. Because vitamin A deficiency affects the synthesis of rhodopsin in the eye, and rhodopsin is the main substance to maintain dark vision. Night blindness patients have decreased vision and dark adaptation at night. Persistent and serious deficiency of vitamin A, especially in malnourished infants, can lead to dry eye disease. When suffering from dry eye disease, the eyes are sensitive to light, the tear secretion stops, the eyelids swell, and the pus is sticky. The eyes become turbid gradually, and the cornea can also be eroded locally, so that the infection can invade, leading to ulcers and other damage to the cornea and other eye tissues. If not treated in time, it often leads to permanent blindness. In the early stage of dry eye disease, when the damage of cornea and deep tissue cells is limited, vitamin A treatment has obvious effect.
Skin lesions are another important manifestation of vitamin A deficiency. The main changes of skin are keratinization of hair follicle and dryness of skin, both of which can occur separately or simultaneously. The early manifestations of vitamin A deficiency include atrophy, dryness and cilia shedding of mucous membrane of oral cavity, throat, respiratory tract and genitourinary tract, reducing its anti infection ability. If vitamin A is not taken enough for a long time, the skin will become dry and rough, the hair follicles will become hyperkeratotic, and the skin looks like chicken skin, which first occurs in the upper arm, thigh, shoulder, and back skin. This is due to the reduction of skin gland secretion.
In addition, vitamin A deficiency will seriously hinder growth and development, especially the development of children and infants. The patient's teeth are not sound, the tooth enamel morphological cells are deformed and dented, and the bone development is slow and insufficient.
Vitamin A deficiency will cause dysfunction of the reproductive system, which is mainly due to its impact on the epithelium of reproductive organs. Pregnant women who lack vitamin A in their diet may have miscarriage in the first three months, and severe vitamin A deficiency may cause teratogenesis or fetal death. Epithelial cell diseases of the reproductive system can affect the vagina and ovary of women and reduce ovulation; Male testis atrophy and sperm dysplasia affect reproductive function.
The lack of vitamin A is also related to the aggravation of diarrhea, kidney stones and bladder stones. Vitamin A deficiency makes the body more sensitive to carcinogens and prone to tumors.
Vitamin A is a fat soluble vitamin. It has many physiological functions such as promoting growth and reproduction, maintaining normal secretion of bone, epithelial tissue, vision and mucosal epithelium. Vitamin A and its analogues can prevent precancerous lesions. When lacking, it is characterized by growth retardation and decreased dark adaptation ability, resulting in night blindness.
Vitamin A is mainly used to prevent and treat night blindness, dry eye disease, and local purulent infection of skin after burn.
Vitamin A is found in humans, various mammals, birds and fish. Beef liver and sheep liver are the highest, with 20000 retinol equivalent per 100g; Secondly, chicken liver is about 10000; Goose, pig and duck livers are also between 4000 and 6000. The yolks of all kinds of eggs are also rich in vitamin A about 1000. Plants do not contain vitamin A, but contain a nutrient called carotene, which can be converted into vitamin A in humans and animals, so carotene is also called provitamin A or provitamin A. Carrots, broccoli and wolfberry are rich in carotene, which is about 1500 retinol equivalent per 100g. In daily life, we can easily distinguish the amount of vitamin A from the color. In general, when the yellow and green color of vegetables and fruits is darker, the content of carotene is higher. Many vegetables and fruits, such as carrots, sweet potatoes, zucchini, pumpkins, corn, apricots, peaches and persimmons, are orange because of their rich carotene content. Green leafy vegetables, especially dark green vegetables, are also very rich in carotene, but their original yellow color is covered by chlorophyll (green).
Deficiency of vitamin A or carotene in the diet or malabsorption may cause vitamin A deficiency. The clinical symptoms are mainly in the eyes and skin.
Night blindness is one of the early symptoms of human vitamin A deficiency. Because vitamin A deficiency affects the synthesis of rhodopsin in the eye, and rhodopsin is the main substance to maintain dark vision. Night blindness patients have decreased vision and dark adaptation at night. Persistent and serious deficiency of vitamin A, especially in malnourished infants, can lead to dry eye disease. When suffering from dry eye disease, the eyes are sensitive to light, the tear secretion stops, the eyelids swell, and the pus is sticky. The eyes become turbid gradually, and the cornea can also be eroded locally, so that the infection can invade, leading to ulcers and other damage to the cornea and other eye tissues. If not treated in time, it often leads to permanent blindness. In the early stage of dry eye disease, when the damage of cornea and deep tissue cells is limited, vitamin A treatment has obvious effect.
Skin lesions are another important manifestation of vitamin A deficiency. The main changes of skin are keratinization of hair follicle and dryness of skin, both of which can occur separately or simultaneously. The early manifestations of vitamin A deficiency include atrophy, dryness and cilia shedding of mucous membrane of oral cavity, throat, respiratory tract and genitourinary tract, reducing its anti infection ability. If vitamin A is not taken enough for a long time, the skin will become dry and rough, the hair follicles will become hyperkeratotic, and the skin looks like chicken skin, which first occurs in the upper arm, thigh, shoulder, and back skin. This is due to the reduction of skin gland secretion.
In addition, vitamin A deficiency will seriously hinder growth and development, especially the development of children and infants. The patient's teeth are not sound, the tooth enamel morphological cells are deformed and dented, and the bone development is slow and insufficient.
Vitamin A deficiency will cause dysfunction of the reproductive system, which is mainly due to its impact on the epithelium of reproductive organs. Pregnant women who lack vitamin A in their diet may have miscarriage in the first three months, and severe vitamin A deficiency may cause teratogenesis or fetal death. Epithelial cell diseases of the reproductive system can affect the vagina and ovary of women and reduce ovulation; Male testis atrophy and sperm dysplasia affect reproductive function.
The lack of vitamin A is also related to the aggravation of diarrhea, kidney stones and bladder stones. Vitamin A deficiency makes the body more sensitive to carcinogens and prone to tumors.
