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Clinical trial fails to find antioxidant Alzheimer’s benefit

By Nathan Gray , 21-Mar-2012
Last updated on 21-Mar-2012 at 15:59 GMT

Supplementation with an antioxidant-rich combination of vitamin E, vitamin C and alpha-lipoic acid (ALA) is not associated with changes in important markers for Alzheimer’s disease, finds new research.

The randomized controlled trial – published in JAMA’s Archives of Neurology –reports thatthe vitamin E, C and ALA combination had no significant effect on cerebrospinal fluid biomarkers related to Alzheimer disease.

Led by Dr Douglas Galasko, of the University of California, San Diego, USA, the research team examined changes in cerebrospinal fluid (CSF) biomarkers related to Alzheimer disease and oxidative stress, cognition and function – finding that the combination of the omega-3 fatty acid ALA and vitamins C and E did not affects key biomarkers for Alzheimer’s disease.

They added that the combination resulted in a lowering of CSF F2-isoprostane levels – suggesting a reduction of oxidative stress in the brain. However, Galasko and his colleagues said supplementation also led to faster cognitive declines – as assessed by the Mini-Mental State Examination (MMSE).

"It is unclear whether the relatively small reduction in CSF F2-isoprostane level seen in this study may lead to clinical benefits in Alzheimer’s disease,” commented Galasko and his colleagues.

“The more rapid MMSE score decline raises a caution and indicates that cognitive performance would need to be assessed if a longer-term clinical trial of this antioxidant combination is considered," they concluded.

Commenting on the study, Dr Harry Rice, vp regulatory & scientific affairs for the omega-3 trade group GOED, told NutraIngredients that he contended such conclusions.

Rice argued that the absence of any cognitive benefits in the current study “does not exclude the possibility that supplementation with antioxidants prior to the onset of Alzheimer Disease could provide a neuroprotective benefit” such as delaying the onset of symptoms, or slowing the progression of the disease.

Study details

The researchers studied the effects of the combined supplements in 78 patients from the Alzheimer's Disease Cooperative Study (ADCS) Antioxidant Biomarker study. The participants were divided into one of three groups: 800 IU/per day of vitamin E (α-tocopherol) plus 500 mg/per day of vitamin C plus 900 mg/per day of α-lipoic acid (E/C/ALA); 400 mg of coenzyme Q (CoQ) three times a day; or placebo.

Sixty-six patients provided serial CSF specimens adequate for biochemical analyses during the 16-week trial.

The authors revealed that the E/C/ALA combination was not associated with significant changes in CSF biomarkers. They explained that supplementation resulted in low CSF F2-isoprostane levels – suggesting a reduction of oxidative stress in the brain. However, the team added that the combination increased MMSE cognitive decline scores.

Galasko and his team also noted that while CoQ was safe and well tolerated in patients, the absence of a biomarker signal in CSF suggests that CoQ, at the tested dose, does not improve indices of oxidative stress or neurodegeneration.

"These results do not support further clinical trial development of CoQ in Alzheimer’s disease," they said. 

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