Vitamin E Paradox in Alzheimer's Disease: It Does Not Prevent Loss of Cognition and May Even Be Detrimental

Abstract

There is controversy as to whether vitamin E is beneficial in Alzheimer's disease (AD). In this study, we tested if vitamin E prevents oxidative stress and loss of cognition in AD. Fifty-seven AD patients were recruited and divided in two groups: placebo or treated with 800 IU of vitamin E per day for six months. Of these 57 patients, only 33 finished the study. We measured blood oxidized glutathione (GSSG) and used the following cognitive tests: Mini-Mental State Examination, Blessed-Dementia Scale, and Clock Drawing Test. Of those patients treated with vitamin E, we found two groups. In the first group, "respondents" to vitamin E, GSSG levels were lower after the treatment and scores on the cognitive tests were maintained. The second group, "non-respondents", consisted of patients in which vitamin E was not effective in preventing oxidative stress. In these patients, cognition decreased sharply, to levels even lower than those of patients taking placebo. Based on our findings, it appears that vitamin E lowers oxidative stress in some AD patients and maintains cognitive status, however, in those in which vitamin E does not prevent oxidative stress, it is detrimental in terms of cognition. Therefore, supplementation of AD patients with vitamin E cannot be recommended without determination of its antioxidant effect in each patient.

Is antioxidant therapy effective to treat alzheimer's disease?

“…This is the case for vitamin E as some meta-analyse have concluded that supplementation with high doses may increase mortality [62][63][64] . Our work has suggested that administering an antioxidant and following changes in cognition is not sufficient as there are patients whose antioxidant status does not change after administration of antioxidant vitamins [59] . It seems that dietary antioxidants are safer but contribute very poorly to improve cognition.…”

“…In those in whom it does not (non-respondent) vitamin E results in an even more pronounced loss of cognition than in patients treated with a placebo. For the patients who experimented a reduction in oxidative stress, cognition was maintained or slightly improved in the six months of the duration of the study [59] .…”

Medicinal Plants Anti-cholinesterase Activity and the Potential for Alzheimer’s Disease Treatment

“…However, experimental result proved that, the inhibition of plasminogen activator inhibitor 1 reduces the level of plasma and Aβ oligomers levels from the brain in transgenic animals [43]. Other studies indicated that, Aβ oligomers clearance is mediated by the hormonal peptide somastotatin by the action of nephrilysin [44].…”

Nutritional strategies in the management of Alzheimer\'s disease: systematic review and meta-analysis

“…There were excluded: studies in vitro, animal models, pharmacological studies, plasma nutrient level measurement, metabolism of nutrients in the physiopathology of AD, nutritional status or food intake in people with dementia; review articles, systematic reviews, monographies, books and chapters of books, however, they were utilized as literature reference to identify other studies that possibly meet the criteria. From the 182 selected studies for examination of full texts, Included studies in the systematic review are characterized in Table 4 (range: 66.5-81.6 y), except for two studies that did not make this data available (192,193).…”

“…Studies with missing data not provided by authors (193,259,(259)(260)(261) or evaluating similar outcomes in the same population and intervention were excluded from analysis (199,213,215). Data analyses show the following results.…”