Following a diet rich in antioxidants such as the Mediterranean diet is associated with decreased risks for both cognitive decline and Alzheimer’s Disease. But is it the case that taking antioxidant supplements is beneficial? In 2010, a NIH study concluded that such supplements do not lower risks of decline and Alzheimer’s. A recent, small but well designed, study went further and showed that these supplements do not help people who already have Alzheimer’s Disease. In some cases, they can even accelerate cognitive decline.
The study included 78 patients with mild to moderate Alzheimer’s disease, who were in their 70s on average and were already getting treated with anti-Alzheimer’s medications.
One-third of the participants took a combination of antioxidants daily: vitamin C, vitamin E and alpha-lipoic acid (i.e., the omega-3 fatty acid ALA). Another third took another kind of antioxidant that tends to be low in people with chronic diseases: coenzyme Q. The final third took placebo pills every day. None of the participants knew which supplements they were taking.
Before starting patients on the supplements, and again after 16 weeks of treatment, researchers tested the participants’ thinking skills, memory and daily functional abilities. They also looked at the participants’ cerebrospinal fluid (CSF), that is the fluid in their brains and spinal cords. They assessed the CSF for proteins and other so-called biomarkers known to be related to brain changes in Alzheimer’s disease (i.e., amyloid and tau pathology).
What was found?
Results showed no effects of any of the antioxidants on the CSF biomarkers related to Alzheimer’s pathology.
There was no effect either on the patients’ ability to perform perform daily activities.
Among participants taking the vitamins C, E and ALA acid, CSF biomarkers showed a reduction of oxidative stress in the brain. To the surprise of the researchers, these participants also showed accelerated cognitive decline (as assessed in the Mini-Mental State Examination or MMSE).
Taking coenzyme Q did not have any effects compared to the placebo pill.
First of all, it is not clear whether the small reduction in the brain oxidative stress found when taking the combination of vitamins C and E, and ALA acid can lead to clinical benefits for the patients with Alzheimer’s Disease.
Second, the finding of accelerated decline is worrisome. It clearly shows that it is not because something is natural that it cannot be dangerous or have negative effects, especially if taken at large doses.
This study confirms the findings from numerous other ones showing that there are no vitamins or supplements to date that have been shown to decrease the risks of developing Alzheimer’s Disease or slow down its progression in people who already have been diagnosed.
The best thing to do so far to fight Alzheimer’s is probably to follow a heart-healthy diet such as the Mediterranean diet. This diet typically involves high intakes of vegetables, fruits, cereals and unsaturated fats (mostly in the form of olive oil), low intakes of dairy products, meat and saturated fats, moderate intake of fish and a regular but moderate alcohol consumption. A recent extensive meta-analysis conducted by the NIH indeed identified this diet as one of the factors most likely to decrease risk of Alzheimer’s Disease and cognitive decline, along with physical activity and cognitive engagement (Williams, et al., 2010).
Galasko, et al. (2012). A Randomized Clinical Trial With Cerebrospinal Fluid Biomarker Measures. Arch Neurol., Published online March 19, 2012. doi:10.1001/archneurol.2012.85
Williams, J. W., Plassman, B. L., Burke, J., Holsinger, T., & Benjamin, S. (2010). Preventing Alzheimer’s Disease and Cognitive Decline. NIH Evidence Report: AHRQ Publication.