Most studies on dietary supplements are mixed. While foods rich in certain nutrients appear to be protective, taking those same vitamins in a pill often don’t have the same positive effect. The same may be true about taking antioxidant supplements in hopes of preventing Alzheimer’s disease (AD).
Antioxidant nutrients combat the oxidative damage done to our bodies every day. Metabolic reactions produce free radicals that interact with other molecules and cause damage to proteins, membranes, and genes. This influences the aging process and is linked to diseases including cancer and Alzheimer’s. Previous studies indicate that oxidative damage is widespread among people with AD.
Although increasing intake of antioxidants can boost the body’s ability to defend itself against oxidative damage, a recent study by researchers with the Department of Neuroscience at the University of California San Diego finds that supplementing certain individual antioxidant nutrients to the diet does not appear to affect certain biomarkers linked to Alzheimer’s disease.
Dr. Douglas R. Galasko and colleagues studied oxidative stress, cognition and function in 78 patients enrolled in the Alzheimer’s Disease Cooperative Study (ADCS) Antioxidant Biomarker Study. The patients were randomized into one of three groups. The first took 800 IU per day of vitamin E (alpha-tocopherol), plus 500 mg of vitamin C and 900 mg of alpha-lipoic acid (ALA).
Because the brain has a high oxygen consumption rate and abundant polyunsaturated acids in the neuron cell membranes, vitamin E is thought to provide protection against free radical damage. Vitamin C, in addition to being an antioxidant, is also needed for the growth and repair of all tissues in the body. Alpha-lipoic acid is found in every cell and helps turn glucose into energy. ALA can help regenerate other antioxidant nutrients as well as act as an antioxidant on its own. Alpha-lipoic acid also passes easily into the brain, possibly helping to protect nerve tissue.
A second group of patients took 400 mg of coenzyme Q three times a day. CoQ is an antioxidant naturally found in the body and is needed for normal cell reactions. Although the nutrient is often promoted as a memory enhancer, there is not enough research yet to prove this is an effective therapy.
The third group of study participants took a placebo.
Sixty-six of the patients provided serial cerebrospinal fluid (CSF) samples adequate enough for analysis during the 16 week trial. The researchers tested for certain protein biomarkers that related to beta-amyloid plaque buildup and tau-based neurofibrillary tangles which interrupt communication within the brain.
Although the group taking the E/C/ALA supplement combination showed a 19% reduction in an oxidative stress CSF biomarker called F2-isoprostane, there was a concerna bout the rapid decline in cognitive function in this group, as assessed using 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 AD. 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 conclude.
Douglas R. Galasko; et al. Antioxidants for Alzheimer Disease: A Randomized Clinical Trial With Cerebrospinal Fluid Biomarker Measures. Arch Neurol, Mar 2012; doi:10.1001/archneurol.2012.85