Low blood levels of vitamin E are linked to greater physical decline in older people, suggests a new study from Yale University School of Medicine.
The researchers obtained measures for several micronutrients, including folate, vitamins B6, B12, D and E, but only the last vitamin was associated with physical decline for older persons, they report in the Journal of the American Medical Association.
"The current study provides empirical evidence that a low concentration of vitamin E is associated with subsequent decline in physical function in a population-based sample of older persons living in the community," wrote lead author Benedetta Bartali.
"Although the findings from this epidemiological study cannot establish causality, they provide a solid base that low concentration of vitamin E contributes to decline in physical function," she added.
Bartali and co-workers recruited 698 community-living people with an average age of 73.7 in Tuscany, Italy. A baseline examination was conducted from November 1998 through May 2000, and the subjects followed for three years. Physical performance was measured using the Short Physical Performance Battery, which included three objective tests of physical function.
Over this short time period, the researchers recorded a 1.1 point decline in physical performance, which exceeded the one point level needed to show a decline.
The researchers calculated on two determinants of physical decline: low vitamin E (alpha-tocopherol) levels among people aged between 70 and 80, and being older than 81. Levels of other micronutrients were not associated with declined levels.
"As the major lipid-soluble antioxidant, vitamin E plays a critical role in the defence from oxidative stress by donating electrons and neutralizing free radicals," wrote Bartali. "Low concentrations of vitamin E may affect this neutralization by creating an imbalance between oxidants and antioxidants and, consequently, a highly reactive milieu.
"Because molecular oxygen promptly accepts unpaired electrons to form reactive oxygen species, this imbalance may lead to excessive formation of reactive oxygen species and, consequently, to oxidative stress that may cause lipid peroxidation and DNA, muscle, and neuronal damage.
"This chain of events may explain, at least in part, our findings on the association between low concentrations of vitamin E and subsequent decline in physical function," she added.
The researchers go on to propose three mechanisms which could explain the relationship between low vitamin E levels and the decline in physical function: The increased level of oxidative stress could result in damage to muscle or DNA; there could be an exacerbation of atherosclerosis or other pathologic conditions; and an increase in neurodegenerative disorders.
Bartali and co-workers note that the subjects did not take vitamin supplements and added that they did not recommend vitamin E supplements to increase levels.
"Approximately 15 to 30 mg/d of dietary alpha-tocopherol [a component of vitamin E] is needed … this amount can be easily reached through diet, from sources such as almonds, tomato sauce, and sunflower seeds among others," stated the researchers.
"Clinical trials may be warranted to determine whether optimal concentration of vitamin E reduces functional decline and the onset of disability in older persons with a low concentration of vitamin E," they concluded.
There are eight forms of vitamin E: four tocopherols (alpha, beta, gamma, delta) and four tocotrienols (alpha, beta, gamma, delta). Alpha-tocopherol (alpha-Toc) is the main source found in supplements and in the European diet, while gamma-tocopherol (gamma-Toc) is the most common form in the American diet.
Source: Journal of the American Medical Association
2008, Volume 299, Issue 3, Pages 308-315
"Serum Micronutrient Concentrations and Decline in Physical Function Among Older Persons"
Authors: B. Bartali, E.A. Frongillo, J.M. Guralnik, M.H. Stipanuk, H.G. Allore, A. Cherubini, S. Bandinelli, L. Ferrucci, T.M. Gill