The researchers, based at Cornell University and Brigham and Women's Hospital, presented their findings at the American Thoracic Society International Conference in New Orleans this week and they say their results show that vitamin E could be used as part of a new preventive strategy for COPD in women.
COPD can cause coughing that produces large amounts of mucus (a slimy substance), wheezing, shortness of breath, chest tightness, and other symptoms, with cigarette smoking the leading cause.
According to the US National Institutes of Health, COPD is a major cause of disability, and it is the fourth leading cause of death in the US, with over 12 million people currently diagnosed with the disease.
The oxidant/antioxidant balance in lung tissue is hypothesized to contribute to chronic obstructive pulmonary disease (COPD) risk, said the researchers, and they noted that observational studies consistently report high antioxidant status associated with lower risk of COPD and asthma.
"As lung disease develops, damage occurs to sensitive tissues through several proposed processes, including inflammation and damage from free radicals.Vitamin E may protect the lung against such damage, said Anne Hermetet Agler, lead researcher and doctoral candidate with Cornell University's Division of Nutritional Sciences.
Agler said that further analysis is required to explore the way vitamin E affects the lung tissue and function. “If results of this study are borne out by further research, clinicians may recommend that women take vitamin E supplements to prevent COPD.”
However, she cautioned that vitamin E supplements could increase the risk of congestive heart failure in cardiovascular disease patients and thus “broader recommendations would need to balance both benefits and risks.”
There are eight forms of vitamin E: four tocopherols (alpha, beta, gamma, delta) and four tocotrienols (alpha, beta, gamma, delta). Alpha-tocopherol is the main source found in supplements and in the European diet, while gamma-tocopherol is the most common form in the American diet.
Tocotrienols are only minor components in plants, although several sources with relatively high levels include palm oil as well as cereal grains and rice bran.
Other associated health benefits for the vitamin include improving the function of the liver thereby strengthening the body's defence system, contributing to a healthy circulatory system and aiding in proper blood clotting and wound healing.
Some studies have shown that vitamin E decreases symptoms of premenstrual syndrome and certain types of breast disease as well as helping to protect against Alzheimer's disease.
According to the team, the strengths of this study include its randomized design, its large trial size, as well as the face validity for the outcome assessment.
“Previous research found that higher intake of vitamin E was associated with a lower risk of COPD, but the studies were not designed to answer the question of whether increasing vitamin E intake would prevent COPD.
Using a large, randomized controlled trial to answer this question provided stronger evidence than previous studies,” said the researchers.
They said they reviewed data compiled by the Women’s Health Study, a multiyear research initiative that ended in 2004 and focused on the effects of aspirin (100mg every other day) and vitamin E (600 IU every other day) in the prevention of cardiovascular disease and cancer in nearly 40,000 women aged 45 years and older for ten years.
“We tested the effect of vitamin E supplementation on risk of incident self reported MD diagnosis of chronic lung disease (CLD), defined as emphysema, chronic bronchitis, or bronchiectasis (single question asked of all women on all follow-up questionnaires), and incident self-reported MD diagnosis of asthma,” explained the researchers.
Although fewer women taking vitamin E developed COPD, Agler noted the supplements seemed to have no effect on asthma, with women on vitamin E diagnosed with asthma at about the same rate as those taking placebo pills.
“Among 38,270 women without self reported history of CLD at randomization, there were 760 new reports of CLD diagnosis in the Vitamin E group and 846 in the placebo group during 373,710 person-years,” found the researchers.
They said an important finding was that the decreased risk of COPD in women who were given vitamin E was the same for smokers as for non-smokers.