Deficiency
Vitamin E deficiency :
Pathogenesis of vitamin E deficiency:
1. When vitamin E is deficient, male testicles atrophy and no sperm are produced , female embryos and placenta atrophy cause miscarriage, hinder the pituitary gland to regulate the secretion of estrogen from the ovary , and induce menopausal syndrome and premature ovarian failure .
2. When vitamin E is lacking: the free radicals produced in the process of human metabolism can not only cause lipid peroxidation of biological membranes, destroy the structure and function of cell membranes, and form lipofuscin; but also denature proteins , inactivate enzymes and hormones, and immune Decreased strength and abnormal metabolism can promote the body's aging or hemolysis.
Food source
Foods rich in vitamin E include: squeezed vegetable oil (see below for specific types), fruits and vegetables, nuts, lean meat, milk, eggs, citrus peels, etc. Fruits and vegetables include kiwi, spinach, cabbage, cabbage, kale , lettuce, sweet potato, and yam. Nuts include almonds, hazelnuts and walnuts. [1]
Squeezed vegetable oils include sunflower seeds, sesame, corn, olives, peanuts, camellia, etc. In addition, safflower, soybean, cottonseed, wheat germ, and cod liver oil all have a certain content of vitamin E. The most abundant is wheat germ. Initially, most natural vitamin E is extracted from wheat germ oil, usually from rape oil and soybean oil.
Vitamin E content of various foods | ||||
Food group | Total tocopherol | alpha-tocopherol | β+γ-tocopherol | delta-tocopherol |
cereal | 0.96 | 0.495 | 0.18 | 0.154 |
Beans | 4.92 | 0.717 | 2.631 | 1.303 |
vegetable | 0.75 | 0.466 | 0.102 | 0.156 |
fruit | 0.56 | 0.381 | 0.13 | 0.03 |
meat | 0.42 | 0.308 | 0.097 | 0.01 |
Milk | 0.26 | 0.087 | 0.112 | 0.021 |
Eggs | 2.05 | 1.637 | 0.409 | 0 |
Aquatic products | 1.25 | 0.817 | 0.19 | 0.248 |
Edible fats | 72.37 | 8.17 | 28.33 | 9.739 |
Body metabolism
Tocotrienols and tocopherols, the latter includes the synthetic stereoisomers of α-tocopherol, vitamin E in the presence of bile acid, pancreatic juice and fat, mixed under the action of lipase to form chylomicrons, in the upper small intestine It is absorbed by the epithelial cells of the intestinal lumen through unsaturated passive diffusion and secreted into the hepatic portal vein leading to the liver. After absorption of various forms of vitamin E, most of them are carried by chylomicrons to the liver through the lymphatic system. The absorption efficiency is estimated to be 51% to 86%. This applies to all vitamin E families-in the absorption process, vitamin E and other vitamins There is no difference between. Vitamin E in the liver enters the plasma through the carrier action of chylomicrons and very low-density lipoprotein (VLDL). In the decomposition process of the blood circulation, the chylomicrons transfer the absorbed vitamin E into the lipoprotein cycle, and the others are used as the remains of the chylomicrons. The main oxidation product of α-tocopherol is α-tocopherol quinone, which generates glucuronic acid after removing the hydrogen-containing aldehyde group. Glucuronic acid can be excreted through bile, or further degraded in the kidneys to produce alpha-tocopheryl acid and excreted from uric acid. Unabsorbed vitamin E is excreted through feces.
In addition, vitamin E is excreted into the intestinal cavity through the liver through bile, it can be reabsorbed or excreted through feces, and all vitamin E will be metabolized, and then excreted through urine.
After reaching the liver, RRR-α-tocopherol is preferentially absorbed by α-tocopherol transfer protein (α-TTP). All other forms are degraded into 2'-carboxyethyl-6-hydroxybenzoxane (CEHC), a process that involves cutting off the phytic acid tail of the molecule and then sulfating or uronic acid. This makes the molecule water soluble and allows it to be excreted in urine. α-Tocopherol can also be degraded into 2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman (α-CEHC) through the same process. But the speed is slower because it is partially protected by α-TTP. A large intake of alpha-tocopherol can lead to an increase in the level of alpha-CEHC in the urine, so this seems to be a way to deal with excess vitamin E.
Alpha-tocopherol transfer protein is encoded by the TTPA gene on chromosome 8. The binding site of RRR-α-tocopherol is a hydrophobic pocket for β-, γ- or δ-tocopherol with lower affinity, or a stereoisomer with the S configuration at the 2-position of the palm. Tocotrienol is also not suitable, because the double bond in the phytic acid tail forms a rigid configuration, which does not match the α-TTP pocket. Despite taking normal amounts of vitamin E, a rare genetic defect in the TTPA gene causes people to show progressive neurodegenerative diseases, which is called ataxia of vitamin E deficiency (AVED). This requires a large amount of α-tocopherol as a dietary supplement to make up for the lack of α-TTP. The role of α-TTP is to move α-tocopherol to the plasma membrane of liver cells (hepatocytes), where it can be integrated into the newly created very low-density lipoprotein (VLDL) molecule. These things deliver alpha-tocopherol to cells in other parts of the body. As an example of the result of priority treatment, the American diet consumes about 70 mg of gamma-tocopherol per day and the plasma concentration is about 2–5 µmol/L; at the same time, the dietary alpha-tocopherol is about 7 mg per day, but the plasma concentration is about 7 mg per day. The concentration is in the range of 11-37 µmol per liter.
intake
The intake of vitamin E among Chinese residents is different from that in the West. The dietary structure is mainly plant-based foods, and the intake of vitamin E is generally high.
Vitamin E intake of Chinese residents in the 1990s
area | Grouped by household income level | |||
average | Low | middle | high | |
Nationwide | 32.2 | 26.6 | 32.3 | 37.6 |
city | 37.4 | 33.1 | 38.2 | 40.9 |
Rural area | 29.5 | 26.6 | 29.1 | 32.8 |
Chinese residents' dietary vitamin E intake (AI)
age | Weight/KG | AI | age | Weight/KG | AI | ||
male | Female | mg/d | male | Female | mg/d | ||
0~ | 6 | 6 | 3 | 14~ | 56.5 | 50 | 14 |
0.5~ | 9 | 9 | 3 | 18~ | 63 | 56 | 14 |
1~ | 13.5 | 12.5 | 4 | Pregnant woman | 14 | ||
4~ | 19 | 18.5 | 5 | wet nurse | 14 | ||
7~ | 28.5 | 25.5 | 7 | 50~ | 14 | ||
11~ | 42 | 41 | 10 | 14 | |||
Account not verified