Pioneering Research Identifies Marked Shortfall of Antioxidants in Alzheimer’s Patients: Is Nutritional Intervention a Viable Preventive Measure?

A novel study has disclosed considerably diminished levels of crucial dietary antioxidants such as lutein, zeaxanthin, and vitamin E in the brains affected by Alzheimer’s disease. The study, which reinforces the relationship between carotenoids (found in vibrant plants) and superior cognitive abilities, posits that a diet rich in carotenoids could potentially reduce the risk of Alzheimer’s and improve overall cerebral wellness.

Alzheimer’s disease, a progressive neurodegenerative condition, is estimated to affect approximately 6 million people in the United States and 33 million people worldwide. A large percentage of this population remains without a formal diagnosis.

A recent article published in the Journal of Alzheimer’s Disease, undertaken by a faculty member from the Virginia Tech Carilion School of Medicine, reports that the concentrations of dietary nutrients such as lutein, zeaxanthin, lycopene, and vitamin E are nearly halved in the brains of Alzheimer’s patients when compared to cognitively healthy individuals. Increased levels of dietary lutein and zeaxanthin have been compellingly associated with superior cognitive performance and decreased susceptibility to dementia or Alzheimer’s disease.

C. Kathleen Dorey, a professor in the Department of Basic Science Education at the medical school, stated, “This research is the first to pinpoint deficits in key dietary antioxidants in brains impacted by Alzheimer’s. Our findings are in line with extensive population-based studies which have concluded that a significantly reduced risk for Alzheimer’s disease is associated with diets abundant in carotenoids, or with elevated levels of lutein and zeaxanthin in the bloodstream or stored as macular pigment in the retina. Furthermore, we posit that diets rich in carotenoids may contribute to optimal brain health across all age groups.”

Carotenoids and Brain Health

Given that normal cerebral functions and the brain’s response to misfolded proteins perpetually produce reactive oxidative molecules, the brain is particularly susceptible to cumulative oxidative damage. Such damage can be mitigated by antioxidants present in a well-balanced diet. Carotenoids are potent antioxidants typically found in colorful plant-based foods. For instance, lutein is abundant in foods like kale and spinach, whereas zeaxanthin is more commonly found in corn and orange peppers.

A groundbreaking finding by Dorey and Neal E. Craft of Craft Technologies in Wilson, North Carolina in 2004 first suggested that the brain selectively stores carotenoids like lutein, zeaxanthin, and beta-cryptoxanthin. Subsequent global research has corroborated improved cognitive function in individuals with elevated levels of lutein and zeaxanthin in their macular pigment, and a reduced risk of dementia in those who have the highest dietary concentrations of these carotenoids.

Dietary Patterns and Alzheimer’s Risk

The Rush University Memory and Aging Project, which monitored the diet and cognitive functions of over 1,000 Chicago residents for more than ten years, revealed that adhering to the MIND diet—which is high in antioxidant-rich fruits, vegetables, nuts, and fish, and low in meat and sugary foods—correlated with a reduced Alzheimer’s diagnosis risk, superior cognitive performance, and decreased Alzheimer’s pathology. Importantly, individuals with the highest decade-long intake of total carotenoids or lutein/zeaxanthin experienced a 50 percent reduction in Alzheimer’s disease risk.

Carotenoids as Neuroprotective Agents

While prior studies have robustly suggested that carotenoids may act as a defensive mechanism against Alzheimer’s-related brain damage, empirical evidence directly linking brain carotenoids with the disease was lacking until the Dorey-Craft report published in the Journal of Alzheimer’s Disease filled this void.

In this recent study comparing the presence of carotenoids in Alzheimer’s and non-Alzheimer’s brains, Dorey and Craft have shown that Alzheimer’s-afflicted brains exhibit notably lower levels of lutein, zeaxanthin, lycopene, and tocopherols. Concentrations of these nutrients were approximately half of what was observed in age-matched brains without Alzheimer’s pathology.

Implications for Diagnosis and Management of Alzheimer’s Disease

The emerging data, highlighting a distinct deficiency in selective carotenoids and tocopherols in Alzheimer’s patients, bolsters the expanding body of evidence suggesting that increased dietary intake of these antioxidants could delay cognitive decline before and possibly after an Alzheimer’s diagnosis.

Other studies indicate that the retina selectively absorbs lutein and zeaxanthin from the diet, forming a yellow macular pigment that not only improves vision but also protects photoreceptors. Through non-invasive methods to measure the macular pigment optical density, it is possible to estimate the brain concentrations of these nutrients.

“As novel therapeutic interventions for Alzheimer’s disease continue to show promise in slowing the progression of the disease, it would be highly encouraging if our research prompted individuals to maintain optimal brain health through a diet rich in colorful carotenoids and regular physical activity. Preliminary studies suggest that such a lifestyle might also reduce the risk of dementia,” concluded Dorey.

Reference: “Low Xanthophylls, Retinol, Lycopene, and Tocopherols in Grey and White Matter of Brains with Alzheimer’s Disease” by C. Kathleen Dorey, Dennis Gierhart, Karlotta A. Fitch, Ian Crandell, and Neal E. Craft, published on June 14, 2023, in the Journal of Alzheimer’s Disease.
DOI: 10.3233/JAD-220460

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More about Alzheimer’s and Antioxidants

• Journal of Alzheimer’s Disease
• Virginia Tech Carilion School of Medicine
• Rush University Memory and Aging Project
• Antioxidants and Cognitive Function
• Carotenoids and Brain Health
• Alzheimer’s Disease Statistics