With more than 6 million people in the United States living with Alzheimer’s disease and numbers on the rise, there is a growing and urgent need for solutions to prevent or delay the condition.
Alzheimer’s disease is the most common type of dementia. Symptoms of the condition includes difficulty with short-term memory, language, and decision making.
Drug trials for Alzheimer’s disease have had low success rates. There is growing interest in finding non-pharmacological means of reducing the risk for Alzheimer’s disease and related dementias, including lifestyle and dietary changes.
There has been particular interest in diets rich in antioxidants, compounds that can prevent or slow the damage to cells caused by oxidative stress.
In a new study, researchers at the Laboratory of Epidemiology and Population Sciences at the National Institute on Aging investigated whether antioxidants in blood were associated with the likelihood of developing Alzheimer’s disease and other dementias.
The findings were published in the journal Neurology.
Mining for nutritional biomarkers
The study used a large dataset that included more than 7,000 people in the U.S., ages 45–90 years and followed for an average of 16–17 years.
The researchers looked at the levels of several antioxidants in the participants’ blood, including vitamins A, C, and E, and several carotenoids, which are pigments found in plants and converted by the body to vitamin A.
They examined relationship between the levels of these antioxidants and rates of Alzheimer’s disease and other dementias.
According to Dr. May Beydoun, lead author of the study, antioxidants might protect the brain from the damage associated with dementia.
“Oxidative stress may occur at an abnormally high level in our body, including within our brain. In such circumstances, consuming antioxidants may help protect our cells from damage, including our brain cells,” Dr. Beydoun told Medical News Today.
Carotenoids may protect against dementia
The results suggest there may be something to this theory. The researchers found that higher levels of the carotenoids lutein and zeaxanthin, which are found together in green leafy vegetables like kale and spinach, were associated with reduced risk of dementia.
Higher levels of β-Cryptoxanthin, a carotenoid found in berries, apples, and papaya, were also associated with a reduced risk of dementia from all causes.
These encouraging findings match Dr. Beydoun’s initial hypothesis that antioxidants might protect against dementia. “Our observational study suggests that if people consume a diet that is rich in specific carotenoids, as reflected by their blood levels of these nutrients, they may be at lower risk of developing dementia with age,” she explained to MNT.
“These findings are consistent with what we’ve seen in similar studies examining specific dietary components and dementia risk,” said Heather Snyder, Ph.D., Vice President of Medical and Scientific Relations at the Alzheimer’s Association.
Randomized controlled trial needed
Although these findings are encouraging, it is important to note that this was an observational study based on measuring antioxidant levels at a single time point.
The protective effect of some of the antioxidants is also reduced when accounting for other factors, such as socioeconomic status and education. The researchers say that randomized controlled trials (RCTs), which randomly assign participants to an intervention versus a comparison or control, could help to better isolate the effects of carotenoids on dementia risk.
“To reach a conclusion for certain, this finding needs to be tested in an RCT. In these RCTs, participants would be randomized to either a treatment (i.e., carotenoid supplementation) or a control group and compared in terms of incidence rates of dementia and/or changes in markers of dementia over time,” Dr. Beydoun added.
More research is also needed to determine the amounts of antioxidants needed to have these beneficial effects.
Depending on future results, it is possible that consuming certain amounts of these antioxidants through food, beverages, and supplements could help to protect the brain, promote healthy aging, and reduce the risk of dementia.
However, Heather Snyder, Ph.D., emphasized the importance of an overall healthy lifestyle, which includes diet and physical activity levels:
“There isn’t a single food, ingredient or supplement that — through rigorous clinical research — has been shown to prevent, treat or cure Alzheimer’s disease or other dementia. There is, however, growing evidence that what we eat can impact our brains as we age, and many studies suggest it is best to eat a heart-healthy diet low in saturated fats and sugar, and high in nutritional foods like vegetables and fruits.
For maximal benefits, a balanced diet would likely need to be combined with other practices aimed to reduce risk of cognitive decline, such as being physically active, to help protect an aging brain.”
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