After watching a loved one struggle with Alzheimer’s disease, the prospect of developing the condition yourself can be terrifying, especially given the fact that effective treatment methods continue to elude researchers. That’s especially true if you’re a patient with a family history of Alzheimer’s and other genetic risk factors. Patient concerns about Alzheimer’s disease risk have sparked decades of research on prevention methods, including strategies that focus on food and nutritional supplements as potential preventive measures. Although this remains a broad area of research exploration, the strongest published data suggests that there are certain diets (like the Mediterranean diet), specific foods (such as olive oil and coffee), and particular nutritional supplements (including phenolic compounds like curcumin and quercetin) that may prove effective for Alzheimer’s disease prevention.
Adopting the Mediterranean Diet as an Alzheimer’s Disease Prevention Strategy
The Mediterranean Diet was first identified as a possible strategy for preventing Alzheimer’s disease based on observations of longer life expectancies and lower incidence of Alzheimer’s disease in the Mediterranean region, particularly around Naples, Italy. Unlike other specialized diets, the Mediterranean Diet is not strictly defined, but it is generally understood to include high levels of consumption of fruits, vegetables, whole grains, beans, nuts, and seeds, combined with moderate consumption of fish, poultry, and dairy products. The diet is also characterized by a low level of red meat consumption.
Over the last several decades, a combination of laboratory, clinical, and epidemiological studies have highlighted the Mediterranean diet as a possible preventive measure for combating Alzheimer’s disease. For instance, a community-wide study was conducted on over 2,200 individuals in New York between 1992 and 1999. The participants’ diets were monitored every 1.5 years, and when the study was published in 2006, the researchers reported a statistically significant association between adherence to the general principles of the Mediterranean Diet and a reduced risk for Alzheimer’s disease.
More recently, researchers have been able to take advantage of advanced technology to provide more solid evidence for a connection between the Mediterranean Diet and Alzheimer’s disease prevention. For instance, in May 2018, researchers from the University of Florence published a breakthrough study in which they used brain imaging to examine the neurological biomarkers of Alzheimer’s disease in individuals who adhered closely to a traditional Mediterranean Diet, as opposed to those who did not. The participants ranged in age from 30 to 70 years old, and the study lasted a total of three years. Based on a combination of both clinical and neuropsychological measures, the researchers were able to use an analytical model to estimate that adherence to a Mediterranean Diet may provide between 1.5 to 3.5 years of protection against Alzheimer’s disease. Although they caution that further investigations of dietary interventions to protect against Alzheimer’s disease are necessary in the future, these promising results demonstrate that the Mediterranean Diet has clear potential as a prevention strategy for Alzheimer’s disease.
Focusing on a Specific Foods: The Potential Benefits of Olive Oil
Some critics of research on the Mediterranean Diet as a prevention strategy for Alzheimer’s Disease warn that diet is too general to produce reliable research results. Although the researchers who have studied the preventive effects of the Mediterranean Diet developed rigorous methods for measuring a patient’s adherence to the diet, these intricate scoring schemes can be hard for patients (and even clinicians) to understand and implement. Put more simply: it’s just too hard for a patient to tell if their Mediterranean Diet is similar enough to those of the study participants for whom improvements were observed. Therefore, some researchers have started to look at the specific protective benefits of individual components of the Mediterranean Diet, which can be more easily integrated into a patient’s daily meal plan. One of the most promising foods is extra-virgin olive oil—a characteristic element of the Mediterranean diet.
In the past few years, several animal studies have offered strong evidence that extra virgin olive oil provides protection against Alzheimer’s disease. For instance, in a 2015 study at the University of Louisiana, researchers observed that exposure to extra virgin olive oil reduced amyloid beta and tau buildup—both of which are hallmarks of Alzheimer’s disease onset and progression—in the brains of mouse models of Alzheimer’s. Similarly, in 2017, a study published in the Annals of Clinical and Translational Neurology confirmed these findings in mouse models, indicating that extra virgin olive oil could reduce the amount of amyloid beta deposition and overall buildup in mouse models while decreasing the amount of phosphorylated tau protein. The researchers also proposed the activation of cell autophagy as a potential mechanism through which these anti-Alzheimer’s activities may be mediated.
Indeed, the most recent studies in the field are providing increasing insight into the specific mechanisms through which the compounds in extra virgin olive oil may be protecting neurons during the onset and progression of Alzheimer’s disease. For instance, one study in the journal Advances in Experimental Medicine and Biology highlighted the role of olive oil-derived phenolic compounds—especially oleuropein aglycone and oleocanthal—in several key processes related to Alzheimer’s disease onset: amyloid-beta peptide and tau aggregation, the impairment of autophagy, and neuroinflammation. These multifunctional phenolic compounds not only have antioxidant activities that help reduce inflammation in the brain, but they are also implicated in the activation of autophagy and the regulation of other pathways that are relevant to the disease development process, such as the phosphorylation of tau protein. Because it appears that olive oil-derived phenolic compounds target Alzheimer’s disease from multiple directions, it is a particularly appealing target food for Alzheimer’s prevention.
Phenolic Compound-Based Supplements for Alzheimer’s Disease
Although the increased consumption of certain foods is one possible way to reduce the risk of Alzheimer’s disease, some clinicians and patients prefer more targeted prevention strategies. This demand has which has sparked research on potential nutritional supplements for Alzheimer’s disease prevention. Some of the supplements that have shown the most potential are plant-based, multifunctional phenolic compounds that are particularly well-known for their antioxidant activities. Considering the fact that the Mediterranean Diet contains many foods that are high in these compounds, this comes as no surprise in light of the previously-discussed research.
One of the most promising polyphenolic compounds is curcumin, which is derived from the turmeric herb. This compound may protect against Alzheimer’s disease in many of the same ways as the phenolic compounds in olive oil. According to a 2017 review of in vitro and in vivo research in the Journal of Alzheimer’s Disease, the latest studies indicate that curcumin can inhibit the formation of amyloid plaques in the brain, promote the disaggregation of existing plaques, modify microglial activity to improve neuroprotection, disrupt oxidative processes that contribute to inflammation, and regulate other pathways with known relevance to the Alzheimer’s disease development process. Because the data indicate that curcumin can have such a broad impact on the brain when it comes to neural protection, the authors concluded that it has “the potential to be more efficacious than current treatments.”
At the same time, the researchers acknowledged the reality that curcumin has a naturally low level of bioavailability. That’s why it’s better for patients to take it as a supplement, rather than directly incorporating it into their diet in food. Because the compound is so poorly absorbed in the gut, it is nearly impossible to add enough curcumin to the food a patient eats to make a clinical difference. Therefore, choosing a curcumin supplement that is scientifically formulated for bioavailability is the only way to take advantage of the multiple benefits of this phenolic compound for Alzheimer’s disease prevention.
Another phenolic compound that has shown promise for Alzheimer’s disease prevention is quercetin. Quercetin is naturally found in some of the foods that characterize the Mediterranean diet, including leafy greens, red wine, citrus fruit, and garlic. It is also the key phenolic component in coffee, another food that is known to have neuroprotective effects against Alzheimer’s disease. In fact, in a study conducted by a group of researchers from the University of British Columbia in 2016, it is quercetin—not caffeine, as other researchers had previously proposed—that is the major neuroprotective component found in coffee. Like curcumin and the phenolic compounds in olive oil, quercetin helps prevent Alzheimer’s through multiple mechanisms, including the attenuation of the release of several key inflammatory proteins and the regulation of key proteins in several Alzheimer’s disease-associated cell signaling pathways, such as the MAPK pathway and the NFkB pathway.
Another relevant study out of the University of Kentucky has indicated that the exposure of primary neurons to quercetin can also reduce the accumulation of amyloid beta, just like curcumin and the phenolic compounds in olive oil. For this study, the researchers measured free radical production in neurons in cell culture, and their findings suggested that the effects of quercetin are partially mediated by the compound’s antioxidant activities. Upon exposure to quercetin, the researchers observed lower levels of amyloid beta-related cytotoxicity, protein oxidation, lipid peroxidation, and apoptosis. When considered in the context of the other studies on phenolic compounds, these data further support the notion that phenolic compounds prevent Alzheimer’s disease through multiple mechanisms, making them some of the most promising potential Alzheimer’s prevention supplements.
Putting Research Into Practice
Overall, when it comes to nutrition for Alzheimer’s prevention, there is not yet a clear consensus within the scientific community on which foods and supplements are best, but strong evidence points to the benefits of the Mediterranean Diet, especially phenolic-compound-containing elements like olive oil. Because food is not always the best way for patients to take in the compounds that may help prevent Alzheimer’s, researchers are also exploring supplement options, with phenolic compounds like curcumin and quercetin showing particular promise for Alzheimer’s prevention. More comprehensive studies in the future will help to clarify the clinical benefits of different dietary options, but clinicians and patients can already start making treatment changes based on the strongest studies, in the hopes of using what is known to start taking preventive action today.
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