The Vitamin Cure. Monte Lai
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 oxidation-reduction mechanism. In addition, bacteria living in the colon can produce vitamin K2, at least part of which is available for human use.
What Are the Risk Factors for Vitamin K Deficiency?
• Anticoagulants. Oral anticoagulant drugs are the major cause of vitamin K deficiency. Warfarin, a commonly prescribed anticoagulant drug, is an inhibitor of vitamin K epoxide reductase, an enzyme that allows the body to recycle and recover vitamin K. Long-term warfarin users are at a high risk of vitamin K deficiency.
• Vitamin K–deficient bleeding in newborns. Bleeding caused by vitamin K deficiency in new babies is a classic example of vitamin K deficiency–related disease in humans. A number of factors—including low vitamin K in the placenta, defective coagulation factors and germ-free digestive tracts in infants, and low vitamin K in breast milk—can cause vitamin K–deficient bleeding in newborns. Vitamin K–deficient bleeding often occurs during the first week of birth. The American Pediatrics Association recommends that newborns be given an injection of 0.5–1 mg of vitamin K to avoid vitamin K–deficient bleeding.
• Diseases. A number of conditions—including liver disease and inflammatory bowel diseases (such as Crohn’s disease and ulcerative colitis), as well as the long-term use of antibiotics—can trigger vitamin K deficiency. All these conditions could kill bacteria living in the colon.
Prevention and Treatment of Diseases
• Prevention. Vitamin K helps prevent osteoporosis (94), cardiovascular disease (48), and calcification of blood vessels.
• Treatment. Vitamin K may treat osteoporosis.
Which Food Items Are Vitamin K Rich?
Dark-green leafy vegetables are excellent sources of vitamin K1. Spinach, broccoli, kale, green beans, oats, and wheat contain vitamin K. Animal-based foods—such as meat, milk, and eggs—also contain vitamin K2. The Japanese food natto is rich in vitamin K2 as well.
This list of vitamin K–rich food items is adapted from information provided by the USDA.
| FOOD | PORTION | VITAMIN K CONTENT, MCG |
% DAILY REFERENCE VALUE
|
|---|