Patient's question:
Please ask what vitamin E is specifically. For example, does it have lozenges or something that can be eaten directly? Thank you!Doctor's answer:
Vitamin E is now commonly available in the form of soft gelatin capsules and is taken orally. Due to its association with fertility, vitamin E is also known as tocopherol and belongs to the phenol class of compounds. There are several natural forms of vitamin E, differing only in the side chains R1, R2, and R3. Vitamin E is related to the reproductive functions of animals. When animals lack vitamin E, their reproductive organs are damaged, leading to infertility. Vitamin E is highly susceptible to oxidation and can protect other substances from oxidation, making it the most effective antioxidant in animals and humans. It can counteract lipid peroxidation reactions in biological membranes, preserving the structural and functional integrity of biological membranes, and slowing down aging. Vitamin E is primarily found in vegetable oils, with high concentrations in wheat germ oil, sunflower oil, peanut oil, and corn oil. It is also abundant in vegetables, legumes, and grains. Deficiency is generally rare.Properties and Stability
Vitamin E is a pale yellow to yellow transparent viscous liquid; it has almost no odor and darkens upon exposure to light. It is sensitive to oxygen and is easily oxidized, thus protecting other oxidizable substances (such as unsaturated fatty acids and vitamin A) in the body. Upon contact with air or ultraviolet light, it gradually oxidizes and deteriorates.
Absorption in the Body
After oral administration, tocopherol is absorbed through the intestines (requiring the presence of bile acids). For example, when 2 grams are taken orally at once, the absorption rate is about 55%. After absorption, it reaches the blood via the lymph as chylomicrons and then binds to plasma β-lipoproteins, with a binding capacity of about 74% of the plasma concentration. The normal blood concentration in adults is approximately 1.05 ± 0.32 mg. It is distributed to all tissues after absorption, with the highest concentrations in the pituitary, adrenal glands, and testes, while lower concentrations are found in the thymus and uterus. Vitamin E is present in the mitochondria and microsomes of these tissues and organs. In tissues, it can be oxidized to tocopherone, which is then reduced to β-tocopherolquinol. The latter binds to glucuronate in the liver and is primarily excreted into the intestine via bile, followed by elimination in the feces, with very little excretion in urine.
Pharmacological Effects
(1) Antioxidant Activity: Free radicals are highly reactive groups widely present in various chemical reactions and play important roles in normal physiological metabolism. If free radicals are excessive, they can trigger chain reactions, leading to lipid peroxidation of unsaturated fatty acids in cell membranes. The large number of newly generated lipid peroxides can damage cell membranes and macromolecular proteins and nucleic acids within cells, causing harm to the body. The antioxidant function of vitamin E is due to its structure as a derivative of phenolpyran, which has a reactive hydroxyl group on its benzene ring, giving it reducing properties. Additionally, it has a saturated side chain on its five-membered ring, which determines its reducing and lipophilic nature. When free radicals enter the lipid phase and undergo chain reactions, vitamin E acts as a free radical scavenger. Vitamin E is highly efficient in counteracting lipid peroxidation caused by free radicals.
(2) Vitamin E and Anti-Aging: Research on vitamin E and aging has spanned decades, with varying conclusions. Overall, vitamin E has little effect on the maximum lifespan of a population but can extend average lifespan, making its anti-aging effect primarily a health benefit.
(3) Vitamin E and Immunity: Deficiency of vitamin E affects the immune function of humans and animals, not only reducing physical immunity but also significantly impacting cellular immunity.
(4) Vitamin E and Cardiovascular Diseases: High intake of vitamin E can reduce the incidence of atherosclerosis, possibly due to its ability to prevent "foam cell" formation in arterial endothelial cells and balance cholesterol metabolism in endothelial cells.
(5) Vitamin E and Liver Studies: Research in the 1980s revealed that vitamin E is one of the important protective factors for liver cell growth. American researchers found that one of the final pathways of liver cell death is the depletion of vitamin E in liver cells, and this mechanism differs from calcium ions, as it utilizes its own form present on the cell surface to exert its protective function. Vitamin E provides protection against various acute liver injuries and has a delaying effect on chronic liver fibrosis.
(6) Vitamin E and Skin: Vitamin E itself is an excellent antioxidant and can enter skin cells to prevent free radical chain reactions. Theoretically, it is superior to superoxide dismutase (SOD) in preventing keratinization when applied to the skin.
The symptoms of vitamin E deficiency are multifaceted, but the most significant effects are observed on the reproductive, muscular, cardiovascular, and hematopoietic systems.
Reproductive System: Male mice that are deficient in vitamin E for a long time develop epithelial degeneration, leading to irreversible infertility. Female mice deficient in vitamin E may terminate pregnancy within about 10 days, resulting in fetal death.
Muscular System: Many animals fed vitamin E-deficient diets develop muscular dystrophy. However, there is no evidence of vitamin E deficiency-related muscular dystrophy in humans.
Cardiovascular System: Skeletal muscle damage caused by vitamin E deficiency is also observed in the myocardium of certain animals. Although heart involvement is usually less severe and less common, it may sometimes be accompanied by electrocardiogram changes, pathological alterations, or even heart failure.
Hematopoietic System: Vitamin E deficiency is associated with anemia. For certain patients with anemia that does not respond to conventional treatment, high doses of vitamin E can be effectively used to treat the condition.
Indications
As a non-prescription medication, vitamin E is considered a nutritional supplement and can be used as a therapeutic agent to treat various diseases caused by free radical damage. It is commonly used for habitual abortion, threatened abortion, infertility, and menopausal disorders, as well as progressive muscular dystrophy.
Adverse Reactions and Precautions
At certain doses, vitamin E is relatively non-toxic. Long-term high intake (400–800 mg per day) may cause nausea, vomiting, dizziness, headache, blurred vision, dry skin, cheilitis, angular cheilitis, gastrointestinal dysfunction, diarrhea, breast enlargement, and fatigue. Overdose (more than 800 mg per day) may lead to prolonged bleeding time, altered endocrine metabolism (thyroid, pituitary, and adrenal glands), changes in immune mechanisms, and menstrual disorders in women. It may also increase the risk of thrombophlebitis or thrombosis.
Drug Interactions
(1) Vitamin E can enhance the absorption, utilization, and liver storage of vitamin A, preventing vitamin A toxicity.
(2) Vitamin E metabolites have an antagonistic effect on vitamin K, reducing blood coagulability, and should therefore be avoided when taken with coumarins and their derivatives.
(3) Drugs that reduce or affect fat absorption, such as cholestyramine, neomycin, sucralfate, and mineral oil, may interfere with vitamin E absorption.
(4) Iron deficiency anemia increases the body's demand for vitamin E during iron supplementation.
(5) Oral contraceptives can accelerate vitamin E metabolism, potentially leading to vitamin E deficiency.
(6) Vitamin E can enhance the cardiotoxic effects of digitoxin and the anticoagulant effects of warfarin.
(7) The concurrent use of estrogens and vitamin E, especially at high doses and prolonged durations, may induce thrombophlebitis.
Dosage and Administration
Oral administration: The conventional non-prescription dose is 5–10 mg three times daily; higher doses are 50–100 mg three times daily. If the daily dose exceeds 400 mg, consult a doctor.
Topical application: 2% ointment, applied 1–2 times daily.