Olive Oil and Alzheimer’s: Choosing the Right Type for Brain Health
For years, olive oil has been lauded as a cornerstone of the Mediterranean diet and a natural ally for brain health. However, a recent Spanish study published in January 2026, sheds light on a crucial distinction: not all olive oils are created equal. The type of olive oil consumed daily could significantly impact cognitive function, and the difference lies in how it’s processed.
The Growing Burden of Alzheimer’s Disease
In France, approximately 1.4 million people live with Alzheimer’s disease or a related illness, with around 225,000 new cases diagnosed each year. Given this significant public health challenge, understanding modifiable lifestyle factors, such as diet, is paramount.
What the Spanish Study Reveals
Researchers from the Universitat Rovira i Virgili (Spain) followed 656 adults aged 55 to 75 for two years as part of the PREDIMED-Plus project. They analyzed participants’ olive oil consumption, the composition of their gut microbiota, and changes in their cognitive performance. The study found that those who consumed virgin olive oil exhibited greater diversity in their gut bacteria and experienced better preservation of cognitive functions – including memory, attention, and executive functions – over time. Conversely, individuals who consumed refined olive oil showed a depleted gut microbiota and a faster rate of cognitive decline.
The key difference stems from the manufacturing process. Virgin olive oil is extracted through mechanical pressing, retaining its natural polyphenols, antioxidants, and vitamins. Refined olive oil undergoes industrial treatments that strip away these beneficial compounds.
How Olive Oil Impacts the Gut-Brain Connection
The study highlights the importance of the gut-brain axis, particularly in individuals aged 55 to 75, a period marked by significant changes in gut microbiota composition. Researchers identified a key bacterium, Adlercreutzia, whose increased presence among virgin olive oil consumers appears to mediate the relationship between diet and cognitive health.
Supporting Evidence from Harvard Research
These findings align with a large-scale study conducted by researchers at the Harvard T.H. Chan School of Public Health, published in JAMA Network Open in 2024. The study followed 92,383 adults for 28 years and revealed that those consuming at least 7 grams (approximately half a tablespoon) of olive oil daily had a 28% lower risk of mortality related to dementia.
| Feature | Extra Virgin / Virgin Olive Oil | Refined Olive Oil |
|---|---|---|
| Cognitive Functions | Preserved or improved | Accelerated decline |
| Diversity of Intestinal Microbiota | Increased | Reduced over time |
| Polyphenols and Antioxidants | Retained | Eliminated by refining |
| Dementia-related mortality (Harvard study, ≥ 7 g/day) | -28% lower risk | Not specified |
Making the Right Choice at the Grocery Store
The simple act of checking the label can create a significant difference. Look for bottles clearly labeled “extra virgin olive oil” or “virgin olive oil” to ensure mechanical extraction without chemical treatment. Avoid bottles simply labeled “olive oil,” as these often contain refined oils or blends. Also, check for mentions of “first cold pressing” or “cold extraction,” which indicate preservation of bioactive compounds. Opting for tinted glass bottles can further protect polyphenols from light degradation.
The Spanish study’s authors emphasize that the quality of fat consumed is more important than the quantity.
Important Considerations and Future Research
The Spanish study was conducted on overweight or obese adults with metabolic syndrome. Further research is needed to determine if these results are generalizable to other populations. The participants’ Mediterranean diet – rich in fruits, vegetables, and fish – may have amplified the observed benefits. Virgin olive oil is most effective as part of a holistic healthy lifestyle.
Although these studies demonstrate a strong association, they do not prove a direct cause-and-effect relationship. Other factors, such as genetics and access to healthcare, also play a role. However, the convergence of Spanish and American data strengthens the hypothesis of a specific protective role for virgin olive oil.
Key Takeaways
- Only (extra) virgin olive oil is associated with preservation of cognitive functions after age 55 (Rovira i Virgili study, January 2026).
- Refined olive oil correlates with depleted microbiota and faster cognitive decline.
- Half a tablespoon per day (≥ 7 g) is associated with a 28% lower risk of dementia-related mortality (Harvard study, 2024).
- Always check the label: only the words “extra virgin” or “virgin” guarantee the absence of refining.
- Store your oil away from light and heat to preserve its polyphenols.
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