? Dr. Jinnan from Johns Hopkins Medical College found that excessive carotene can affect the synthesis and secretion of lutein in ovaries, and some even cause amenorrhea, anovulation and menstrual disorder. The researchers explained that this may be? -Carotene interferes with steroid synthesis. A doctor once found that six women with irregular menstruation due to eating too many carrots had Huang Chengcheng's ovaries, which were called "golden ovaries". ?
Does carotene really have such a "magical" function?
Understand carotene
To understand carotene, we must first understand carotenoids. Carotenoids are macromolecular organic compounds and their derivatives, with about 600 kinds. Its * * * has the same feature, that is, they all contain 8 isoprene units. According to the structure, carotenoids can be divided into two types: lutein with one or more oxygen atoms and carotene without oxygen atoms. 1
Lutein (I)? -Carotene (middle) and? -Carotene (as follows)
Plants need energy through photosynthesis, and photosynthesis needs the participation of photosynthetic pigments. Therefore, accessory pigments, as a photosynthetic pigment, is widely distributed in higher plants, such as tomatoes, oranges, peppers, carrots and corn. To exaggerate, where there are green flowering plants, there are carotene. 1
Therefore, if carotene is really harmful to pregnancy, it is useless to eat less carrots.
The benefits of carotene to people, especially pregnant women and fetuses.
The physiological function of carotene can be realized in two ways: one is to transform into vitamin A in the body, and the other is to directly participate in some metabolic processes.
1928, scholars discovered a molecule? -Carotene can be converted into two molecules of vitamin A under the action of enzymes in the body. Subsequent research confirmed that carotene is an important source of vitamin A in human body. And vitamin A is too important for human body.
First of all, vitamin A is the carrier of glycoprotein synthesis. Glycoprotein is an important structural substance of epithelial cells and immunoglobulin. Therefore, the lack of vitamin A will affect the synthesis of respiratory tract, digestive tract and antibody.
More attention should be paid to the effect of vitamin A on vision. There are rod-shaped cells and cone-shaped cells in the human retina, and both of them have the photosensitive pigment rhodopsin. The formation and physiological function of this pigment are closely related to vitamin A. Lack of vitamin A will have an impact on vision, and in severe cases, it will cause night blindness, which means that you can't see clearly in the dark or in poor light. three
Human retinal structure
For the fetus, vitamin A plays an important role in cell division, the development and maturity of fetal organs and bones, and the maintenance of immune system (enhancing anti-infection ability).
In view of this, the World Health Organization advises pregnant women, especially those in underdeveloped areas (Africa and Southeast Asia), to improve the environment during pregnancy by eating foods rich in vitamin A or carotene, such as carrots, pumpkins and whole milk. For those with poor daily diet, cod liver oil and cod liver oil can be used in small doses. -Carotene or something? -carotene-vitamin a mixed preparation.
However, when the intake exceeds 10000 IU (3 mg) per day or 25000 IU (7.5 mg) per week, vitamin A may be toxic to pregnant women and their fetuses. As a precursor of vitamin A, do pregnant women supplement it? -Carotene may be better than vitamin A-based supplements, because no? -Reports of birth defects caused by excessive carotene. four
Relationship between Carotene and Steroid Synthesis
In addition to synthesizing vitamin A, carotene itself is an effective antioxidant in human body, which plays an important role in scavenging free radicals and preventing lipid peroxidation.
A large number of studies show that adding? -Carotene can improve animal fertility. The mechanism is not clear. One explanation is that, as an antioxidant, it can protect highly active follicles and uterine cells from free radicals, protect important organelles, and help ovarian cells achieve the best level of steroid function and secretion of important uterine proteins, thus improving the uterine environment. five
Another study shows that carotene can stimulate the synthesis of lutein and estrogen. Lack of carotene will lead to early embryo death, non-fertilization, and decreased pregnancy rate. 3、5
Toxicity of carotene
Traditionally,? -Carotene has low toxicity. For ethical reasons, there is no direct evidence of human toxicity test, but there is a lot of indirect evidence that the daily intake of 15 to 50 mg? -Carotene has no side effects. Under normal circumstances, raw carrots only contain about 8mg per 100 g? -Carotene, ordinary people don't have to worry? -Carotene poisoning.
If a large amount of carotene is ingested for a long time, it may be deposited in skin, subcutaneous adipose tissue and other parts. The clinical manifestation is yellow skin, which is called carotene anemia. Generally speaking, it is considered harmless. Stop eating foods rich in carotene and it will be relieved in a few weeks.
Comparison between normal palm (left) and carotene anemia palm (right)
No matter pregnant women, pregnant women or ordinary people, in terms of nutrition, what needs to be done most is a balanced diet. Neither partial eclipse, vicious dieting, nor blind use of nutritional supplements; There is no need to exaggerate the advantages of certain foods and worry too much.
Truth:? -Carotene is an indispensable trace element for pregnant women and fetuses. Normal diet will not lead to poisoning, let alone infertility.
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refer to
1 Li fuzhi, Liu Fei, Zeng xiaoxi, et al. research progress of natural carotenoids [J]. food industry science and technology, 2007,28 (9): 227-232.
2 Li, Zhou, Gao Feng, et al. Physiological functions of carotenoids and their absorption and metabolism in animals [J]. Animal Husbandry and Veterinary Medicine, 2005,37 (9): 58-61.
3 Zhu, Che, et al. Research progress on physiological function and extraction technology of carotene [J]. Journal of xihua university: Natural Science Edition, 2005,24 (1): 71-76.
4 World Health Organization, Vitamin A supplementation for pregnant women, 20 1 1.
5, Qi Desheng. -Physiological function of carotene and its application in animal production [J]. Veterinary drugs and feed additives, 2007, 12(5): 26-28.
6 Diplock A T. Safety of antioxidant vitamins and β -carotene [J]. American Journal of Clinical Nutrition,1995,62 (6):1510s-15/6s.
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Author: Zhao Yanchang