Daily reference value of vitamin E is 30 IU according to the 2013 FDA food-labeling guidelines.
What Are the Recommended Dietary Allowances for Vitamin E?
| 1–3 years | 9.0 IU |
| 4–8 years | 10.5 IU |
| 9–13 years | 16.5 IU |
| 14–18 years | 22.5 IU |
| 19 years and older | 22.5 IU |
The upper daily intake limit of vitamin E is 1,000 IU.
Vitamin E Supplements
• Dosage. The most common dosages of vitamin E supplements are 20–500 IU. Both International Units (IU) and the weight unit milligram (mg) are often used to quantify vitamin E, with 1 IU being equal to 0.45 mg of natural vitamin E or 0.67 mg of synthetic vitamin E.
• Types. The two major vitamin E supplements are natural vitamin E containing d-alpha-tocopherol and synthetic vitamin E containing dl-alpha-tocopherol. Natural vitamin E is better than synthetic vitamin E in terms of bioavailability as well as its retention time in the body.
• Alzheimer’s disease. Vitamin E can improve the symptoms of Alzheimer’s disease. Adding vitamin E to prescribed medications like acetylcholinesterase inhibitors significantly improves daily activities, such as dressing and bathing oneself, in patients with Alzheimer’s disease. Vitamin E supplementation can also improve cognitive impairment and prevent its progression to Alzheimer’s disease.
Vitamin E Supplements
• Vitamin E can help combat disease in those who are carriers of alpha-tocopherol transfer protein mutant genes, fat malabsorption syndrome, chronic cholestasis, cystic fibrosis, and Crohn’s disease.
• Vitamin E can also delay the onset of chronic steatorrhea, such as celiac disease and chronic pancreatitis.
Safety Issues
• Blood-thinning effect. High-dose vitamin E can induce a blood-thinning effect and add to the risk of stroke. Patients who take blood-thinning drugs are particularly vulnerable to this effect of vitamin E.
• Diabetes. Supplementation with high-dose vitamin E may lead to uncontrollable blood glucose levels in patients with diabetes.
• Chemotherapy. Cancer patients who receive chemotherapy should not take vitamin E supplements until they complete their treatment.
• Shortened life. Supplementation with high-dose vitamin E could shorten the life-span of elderly people who are in poor health.
• Blood clotting. Supplementation with high-dose vitamin E may interfere with the blood-clotting activity of vitamin K.
What Types of Drugs May Interact with Vitamin E?
• Cholesterol-lowering medications that reduce fat absorption can lower vitamin E absorption by the intestines.
• Anticonvulsant drugs may reduce blood levels of vitamin E.
Vitamin K is the anticoagulation vitamin. In 1929, Henrik Dam used oil to extract and remove all lipid-soluble substances from animal feed so that it contained only water-soluble substances and then fed that to chickens. He found that the chickens suffered muscle bleeding and slow blood coagulation. Apparently, some molecule in the lipid-soluble substances was important for blood clotting. In 1935, Dam isolated a lipid-soluble substance from the animal feed and called it vitamin K. K came from the first letter of the German word Koagulation, meaning “blood clotting.” In subsequent years, scientists confirmed that the chemical structure of vitamin K was phylloquinone.
Lipid-soluble vitamin K is an essential nutrient for blood coagulation in the body. Vitamin K consists of a group of structurally related naphthoquinones. Among them, vitamins K1 and K2 are most important to human health. Vitamin K1, also known as “phylloquinone,” comes from plant-based foods, particularly dark-green leafy vegetables. Vitamin K2, also known as “menadione,” is produced mainly by bacteria living in the human colon.
What Are the Major Functions of Vitamin K?
• Blood coagulation. Blood coagulation is required to stop bleeding after injury. Vitamin K is an essential cofactor for enzymes participating in the blood coagulation process. Vitamin K deficiency can adversely affect blood coagulation and bring about uncontrollable bleeding.
• Bone density. Vitamin K helps maintain bone health. Supplementation with vitamin K augments bone density and curtails the risk of bone fractures in patients with osteoporosis.
• Calcification of blood vessels. Vitamin K enhances the activity of matrix Gla proteins, which inhibit calcification of blood vessels and prevent the formation of atherosclerosis.
What Are the Symptoms of Vitamin K Deficiency?
• Symptoms of vitamin K deficiency include nosebleeds, bleeding gums, and/or blood in the urine and stool. Fortunately, deficiency is rare because vitamin K is widely distributed in plant-based foods, and the body is able to recycle oxidized vitamin K through a regenerative
