Alzheimer patients were 85% less likely to have the highest levels of vitamin E, compared with people with normal cognitive function, researchers from six European countries report in Neurobiology of Aging.
In addition, people with mild cognitive impairment and Alzheimer’s were over 90% less likely to have the highest levels of vitamin E in the tocotrienol form, added the researchers, led by Francesca Mangialasche from the Karolinska Institute in Stockholm.
“The present study shows that plasma concentrations of different vitamin E forms are related to the diagnosis of [Alzheimer’s disease] and [mild cognitive impairment] in elderly subjects,” they wrote.
“The increasing evidence about vitamin E family neuroprotective properties warrants further investigation of their role in age-related cognitive decline and [Alzheimer’s disease], to better define the composition of vitamin E supplements that can be tested in the prevention/treatment of [Alzheimer’s disease].”
Dr Mangialasche and her co-workers also noted that analysis of vitamin E forms in the blood may help to identify elderly people who could benefit from vitamin E supplementation.
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.
The build-up of plaque from beta-amyloid deposits is associated with an increase in brain cell damage and death from oxidative stress. Wasting in the brain, or atrophy, is a common symptom of mild cognitive impairment, and can be an early warning to signs of dementia.
Vitamin E, an antioxidant, has been proposed to offer a potential nutritional approach to reduce the risk of such impairment. Indeed, a randomized, placebo-controlled trial reported a beneficial effect of alpha-tocopherol (2000 IU total per day) in Alzheimer patients (New England Journal of Medicine, 1997, Vol. 336, pp. 1216-22).
Alpha-tocopherol is the only form being tested in such trials, however, and the new study is said to be the first to evaluate all the forms of vitamin E in relation to Alzheimer’s disease and mild cognitive impairment.
The new study was described as “unique” by Dr Barrie Tan, president of American River Nutrition, a Massachusetts-based supplier of tocotrienols extracted from annatto.
“This clinical study is definitely the first that I have seen, where the effects were evaluated in total, which is the beneficial effects point to tocopherols, tocotrienols, vitamin Es (all isomers combined), not just only to alpha-tocopherol,” he told NutraIngredients-USA.
The European researchers analyzed data from 168 Alzheimer patients, 166 people with mild cognitive impairment, and 187 people with normal cognitive function.
The data indicated that people with Alzheimer’s disease and mild cognitive impairment had lower blood levels of total tocopherols, total tocotrienols, and total vitamin E.
After crunching the numbers, the researchers calculated that people with both forms of cognitive decline were 85% less likely to have the highest average levels of total tocopherols and total vitamin E. In addition, they were 92% and 94%, respectively, less likely to have the highest average levels of total tocotrienols.
Dr Mangialasche and her co-workers added that subjects with Alzheimer’s disease and mild cognitive impairment displayed higher levels of vitamin E damage markers compared to the cognitively normal group of subjects. This result suggested a direct link between oxidative stress in early Alzheimer’s onset and low levels of vitamin E.
Commenting on the results, American River Nutrition’s Dr Tan said that, further analysis of the data showed that the highest protection was offered by alpha-tocotrienol, delta-tocotrienol, and gamma-tocotrienol.
“This suggests that all tocotrienols, except beta-tocotrienol, and gamma-tocopherol afford the strongest protection to cognitive impairment.”
Strengthening the role of tocotrienols for cognitive health
The study was also welcomed by WH Leong, VP of tocotrienol supplier Carotech Inc. “We now know that each and every vitamin E form, tocopherols and tocotrienols, are required for preserving cognitive functions, especially in older people,” he said.
“We have always emphasized the need to take the 8 forms of vitamin E, as naturally found in our diet and as nature intended. It is not right to say that we only need one type of vitamin E.
“Consumers should be taking a full spectrum vitamin E especially for improving/ preserving cognitive health and performance,” added Leong.
Source: Neurobiology of Aging
Published online ahead of print, doi:10.1016/j.neurobiolaging.2011.11.019
“Tocopherols and tocotrienols plasma levels are associated with cognitive impairment”
Authors: F. Mangialasche, W. Xu, M. Kivipelto, et al.