Summary: Higher blood levels of the antioxidants lutein, zeaxanthin, and beta-cryptoxanthin were associated with a lower risk of developing dementia decades later, according to a long-term study.
Source: AAN
People who had higher concentrations of certain antioxidants in their blood were less likely to develop dementia over the following years, a study published in Neurology reports.
Researchers followed 7,283 adults who were at least 45 years old at the study’s start. Each participant received a physical exam, an interview and blood testing to measure antioxidant levels at baseline. The group was then monitored for an average of 16 years to determine who went on to develop dementia.
The research focused on several antioxidant carotenoids, including lutein, zeaxanthin and beta-cryptoxanthin. Lutein and zeaxanthin are commonly found in green, leafy vegetables such as kale, spinach, broccoli and peas, while beta-cryptoxanthin is abundant in fruits like oranges, papaya, tangerines and persimmons.
Participants were grouped into three categories based on their measured blood antioxidant levels. Those in the highest group for lutein and zeaxanthin had a lower incidence of dementia compared with people in the lower groups. Quantitatively, every standard deviation increase in lutein and zeaxanthin—about 15.4 micromoles per liter—was linked with a roughly 7% reduction in dementia risk. For beta-cryptoxanthin, each standard deviation increase—about 8.6 micromoles per liter—corresponded to an approximately 14% lower risk.
The study authors caution that these associations were modestly weakened after accounting for socioeconomic and lifestyle factors such as education, income and physical activity. “It’s important to note that the effect of these antioxidants on the risk of dementia was reduced somewhat when we took into account other factors such as education, income and physical activity, so it’s possible that those factors may help explain the relationship between antioxidant levels and dementia,” said study author May A. Beydoun, Ph.D., MPH, of the National Institute on Aging at the National Institutes of Health in Baltimore, Maryland.
The researchers point to a plausible biological mechanism: antioxidants can neutralize oxidative stress, a process that can damage cells and has been implicated in brain aging and neurodegeneration. While this mechanism supports the observed association, the study cannot prove that higher antioxidant levels cause the reduced dementia risk.
A key limitation is that antioxidant concentrations were measured only once at the start of the study. Single measurements may not reflect lifelong exposure or long-term dietary patterns, and levels can change over time. Because of this, and because observational studies can be influenced by other factors, the authors emphasize the need for additional research to test whether increasing intake of these antioxidants can directly protect the brain from dementia.
Despite limitations, the findings add to a growing body of research linking diet and brain health. Foods rich in lutein, zeaxanthin and beta-cryptoxanthin—green leafy vegetables and certain fruits—are part of dietary patterns that have been associated with better cognitive outcomes in other studies. Incorporating a variety of vegetables and fruits into regular meals supports overall nutrition and may contribute to long-term cognitive resilience.
The study’s long follow-up period and the measurement of blood biomarkers strengthen its contribution, but cautious interpretation remains important. The observed associations are statistically meaningful yet modest in size, and they may reflect a combination of direct biological effects and broader socioeconomic or lifestyle differences among participants.
In summary, this long-term analysis suggests that higher blood levels of certain antioxidant carotenoids—particularly lutein, zeaxanthin and beta-cryptoxanthin—are associated with a lower risk of dementia over many years. While these findings are encouraging, randomized trials or further longitudinal research with repeated measurements would be needed to determine whether interventions that raise antioxidant levels can reduce dementia risk.
About this dementia research news
Author: Press Office
Source: AAN
Contact: Press Office – AAN
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Original Research: The findings will appear in Neurology