Vitamin E – Nature’s Powerful AntioxidantDr. Zoltan P. Rona, MD, M.Sc. June 1, 2007
Vitamin E is not a single nutrient but exists in nature as a family of eight different antioxidants. Some vitamin E supplements sold in health food stores and pharmacies contain only alpha-tocopherol but, in nature, there are four tocopherols. These consist of alpha-, beta-, gamma- and delta-. There are also four tocotrienols (also alpha-, beta-, gamma- and delta-). Together with the tocopherols, they make up what has been called the vitamin E complex.
Antioxidants are substances that protect healthy cells from being damaged by toxins. In the case of vitamin E, the fats in the cell membranes are what are being protected by this unique fat-soluble antioxidant. Antioxidants also play a role in destroying diseased cells such as the ones that occur in cancer. Unfortunately, even the most experienced oncologists still discourage patients who supplement with antioxidants in the mistaken belief that antioxidants “protect cancer cells.” As is now very obvious from peer-reviewed scientific studies, this dogma is unproven and antioxidants like vitamin E are a must for any cancer victim, especially for those who are being treated with either radiation or chemotherapy (see the periodical Cancer Treatment Reviews, May, 2007).
FUNCTIONS OF THE VITAMIN E COMPLEX
- Maintains the integrity of cell membranes throughout the body, and protects the fats in low density lipoproteins (LDLs) from oxidation which have also been called “the bad cholesterol”.
- Inhibits the activity of protein kinase C, an important cell signaling molecule that controls the activity of immune and inflammatory cells.
- Inhibits platelet aggregation and enhances vasodilatation (better blood flow).
- Associated with decreased risk of myocardial infarction (heart attack) or death from heart disease in both men and women.
- Associated with protection from cataracts in some studies.
- Might have value in the treatment of cardiovascular disease, especially coronary artery disease.
- Shown to enhance specific aspects of the immune response that appears to decline as people age.
- Tocotrienol components of vitamin E complex have been found to lower LDL (”bad”) cholesterol.
- Can inhibit proliferation and induce apoptosis (programmed cell death) in a number of cancer cell lines.
- Associated with reduced cancer rates in some studies, especially prostate cancer.
- Associated with a reduction of oxidative stress markers and may be beneficial for individuals with diabetes.
- Associated with a significant slowing of the progression of Alzheimer’s dementia.
VITAMIN E COMPLEX DEFICIENCY
Deficiency of vitamin E is seen in those suffering from severe malnutrition, genetic defects affecting the alpha-tocopherol transfer protein, and fat malabsorption syndromes (e.g. children with cystic fibrosis or cholestatic liver disease, who have an impaired capacity to absorb dietary fat and therefore fat-soluble vitamins).
Deficiency of vitamin E results mainly in neurological symptoms, including impaired balance and coordination (ataxia), injury to the sensory nerves (peripheral neuropathy), muscle weakness (myopathy), and damage to the retina of the eye (pigmented retinopathy aka retinitis pigmentosa).
Suboptimal intake of vitamin E is relatively common in the U.S. (27% of Caucasians, 41% of African Americans, 28% of Mexican Americans and 32% of the other groups were found to have insufficient blood levels of alpha-tocopherol).
Many drugs reduce the absorption of vitamin E and can create deficiency states: cholestyramine, colestipol, isoniazid, mineral oil, orlistat, sucralfate, and the fat substitute, olestra. Anticonvulsant drugs such as phenobarbitol, phenytoin, or carbamazepine may decrease plasma levels of vitamin E.
RECOMMENDED DIETARY ALLOWANCE (RDA)
The RDA was revised in 2000. Unfortunately, the latest RDA for vitamin E continues to be based on the prevention of deficiency symptoms rather than on health promotion and the prevention of chronic disease.
The Recommended Dietary Allowance (RDA) for RRR-alpha-tocopherol (d-alpha-tocopherol)
|Life Stage||Age||Males; mg/day (IU/day)||Females; mg/day (IU/day)|
|Infants||0-6 months||4 mg (6 IU)||4 mg (6 IU)|
|Infants||7-12 months||5 mg (7.5 IU)||5 mg (7.5 IU)|
|Children||1-3 years||6 mg (9 IU)||6 mg (9 IU)|
|Children||4-8 years||7 mg (10.5 IU)||7 mg (10.5 IU)|
|Children||9-13 years||11 mg (16.5 IU)||11 mg (16.5 IU)|
|Adolescents||14-18 years||15 mg (22.5 IU)||15 mg (22.5 IU)|
|Adults||19 years and older||15 mg (22.5 IU)||15 mg (22.5 IU)|
|Pregnancy||all ages||15 mg (22.5 IU)|
|Breastfeeding||all ages||19 mg (28.5 IU)|
From USDA food composition database (http://www.nal.usda.gov/fnic/foodcomp/search/)
|Food||Serving||Alpha-tocopherol (mg)||Gamma-tocopherol (mg)|
|Olive oil||1 tablespoon||1.9||0.1|
|Soybean oil||1 tablespoon||1.2||10.8|
|Corn oil||1 tablespoon||1.9||8.2|
|Canola oil||1 tablespoon||2.4||4.2|
|Safflower oil||1 tablespoon||4.6||0.1|
|Sunflower oil||1 tablespoon||5.6||0.7|
|Spinach||½ cup, raw chopped||1.8||0|
|Carrots||½ cup, raw chopped||0.4||0|
|Avocado (California)||1 medium||3.4||0.6|
There are several supplement forms offered by a variety of different manufacturers:
- Vitamin E complex **highly recommended**
- Mixed tocopherols (with or without tocotrienols aka “Total E”) **highly recommended**
- d-alpha-tocopherol (natural) *adequate but not ideal*
- dl-alpha-tocopherol (synthetic) *not recommended because not as bioavailable or easily absorbed by the body*
- Ester forms (natural), alpha-tocopheryl succinate and alpha-tocopheryl acetate *recommended in some circumstances because more resistant to oxidation during storage than unesterified tocopherols; equivalent to d-alpha-tocopherol.
- Alpha-tocopheryl phosphates (natural) (Ester-E®) *status uncertain with no evidence of significant benefit compared to other forms.*
VITAMIN E TOXICITY
The table below provides the tolerated upper limits of daily vitamin E supplementation by individuals at different ages. It is based on a combination of numerous published studies and clinical experience.
Tolerable Upper Intake Level (UL) for Alpha-Tocopherol
|Age Group||mg/day (IU/day d-alpha-tocopherol)|
|Infants 0-12 months||Not Possible to Establish*|
|Children 1-3 years||200 mg (300 IU)|
|Children 4-8 years||300 mg (450 IU)|
|Children 9-13 years||600 mg (900 IU)|
|Adolescents 14-18 years||800 mg (1,200 IU)|
|Adults 19 and older||1,000 mg (1,500 IU)|
POTENTIAL PROBLEMS WITH VITAMIN E
Although rare, adverse reactions to vitamin E are possible and include:
- Impaired blood clotting resulting in an increased likelihood of hemorrhage in some individuals with doses over 1000 IU daily; may be a problem for some with pre-existing blood clotting disorders, with certain anti-coagulation prescription drugs and individuals with blood Type “O” (see Eat Right For Your Type by Dr. Peter D’Adamo).
- Worsening of vitamin K deficiency bleeding with doses greater than 1000 IU daily.
- Acceleration of retinitis pigmentosa that is not associated with vitamin E deficiency with supplementation of 400 IU/day of vitamin E.
VITAMIN E CONTROVERSY
Vitamin E continues to be the most popular of all the nutritional supplements despite numerous attacks on its validity as a preventive and therapeutic nutrient. During the past three decades, medical journal warnings about vitamin E’s lack of effectiveness as well as its potential toxicity have failed to stop millions of people in both Canada and the USA from taking it as a regular habit. The main reason for this is that all the negative articles have been very poorly done or used synthetic vitamin E to draw their conclusions. Oncologists who continue to profess that vitamin E supplements will reduce the effectiveness of radiation and chemotherapy have simply not kept up with latest research that proves otherwise.
The most recent frivolous attack on the benefits of vitamin E and other antioxidants was a JAMA (Journal of the American Medical Association) article (Bjelakovic G, et. al., 2007 Feb 28; 297 (8): 842-57) that concludes, “Treatment with beta carotene, vitamin A and vitamin E may increase mortality.”
According to Dr. Jeffrey Blumberg, Director of the Antioxidants Research Laboratory at Tufts University in Boston, Massachusetts, “This is a flawed analysis, the totality of the evidence indicates that antioxidants from foods or supplements have many health benefits, including reduced risk for cardiovascular disease, some types of cancer, eye disease and neurodegenerative disease. They are a key to an enhanced immune system and resistance to infection.”
Like practically all negative studies on vitamin E, the conclusions of this JAMA study were based entirely on a selected statistical review of old data. There was no experimental design or actual study done. Further, it was published by the same scientists who denounced antioxidants in a Lancet article in 2004. Most credible scientists dismissed the latter as science fiction, but the authors are back again. They discount most of the well-established scientific support for antioxidants, and then go on to conclude that antioxidant vitamins increase death from all causes.
There is more than ample evidence supporting the supplementation of vitamin E for all adults on a regular basis. Depending on one’s state of health, optimum doses will vary from 400 to 1200 IU daily of the mixed tocopherols (vitamin E complex). For conditions where inflammation is an issue (e.g. arthritis), doses of over 2400 IU may be quite effective in reducing pain, redness and swelling. If one is on anti-coagulant drugs or has other serious health issues, it’s best to consult a natural health care practitioner for advice on optimum dosages.
Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis. JAMA. 2007 Feb 28;297(8):842-57
L. Iuliano; F. Micheletta; M. Maranghi; G. Frati; U. Diczfalusy; F. Violi (2001). “Bioavailability of Vitamin E as Function of Food Intake in Healthy Subjects”. Arteriosclerosis, Thrombosis, and Vascular Biology 21: e34–e37.
Jiang Q et al.Gamma tocopherol, the major form of vitamin E in the US diet, deserves more attention. Am J Clin Nutr 2001; 74: 714-22.
Walker M, New/Old Findings on Unique Vitamin E, Townsend Letter for Doctors and Patients, No. 111, 1992, p. 826
MacWilliam L,What Makes Gamma Tocopherol Superior to Alpha Tocopherol, LE Magazine, Report, April 2006
Traber MG and Packer L. Vitamin E: Beyond antioxidant function. Am J Clin Nutr 1995;62:1501S-9S.
Traber MG. Does vitamin E decrease heart attack risk? summary and implications with respect to dietary recommendations. J Nutr. 2001;131(2):395S-397S.
Cherubini A, Zuliani G, Costantini F, et al. High vitamin E plasma levels and low low-density lipoprotein oxidation are associated with the absence of atherosclerosis in octogenarians. J Am Geriatr Soc. 2001;49(5):651-654.
Yusuf S, Dagenais G, Pogue J, Bosch J, Sleight P. Vitamin E supplementation and cardiovascular events in high-risk patients. The Heart Outcomes Prevention Evaluation Study Investigators. N Engl J Med. 2000;342(3):154-160.
Keith I. Blocka, Amanda C. Kocha, Mark N. Meada, Peter K. Tothya, Robert A. Newmanc, and Charlotte Gyllenhaala, Impact of antioxidant supplementation on chemotherapeutic efficacy: A systematic review of the evidence from randomized controlled trials; Cancer Treatment Reviews, May 2007.
Dr. Zoltan P. Rona practises Complementary Medicine in Toronto and is the medical editor of The Encyclopedia of Natural Healing. He has also published several Canadian best-selling books, including Vitamin D: The Sunshine Vitamin. Visit his website at: http://www.highlevelwellness.ca For appointments, call (905) 764-8700; Office: 390 Steeles Ave. W. Unit 19, Thornhill, ON