A first-ever meta-analysis finds a small benefit for extra virgin olive oil in cognitive impairment and dementia — the trials are randomized but the certainty is low
STUDY: Simão VC et al, Clinical Nutrition ESPEN 2026; doi:10.1016/j.clnesp.2026.102977, PMID: 41740793
STUDY TYPE: Systematic review and meta-analysis
FUNDING: Independent
Background
The “extra” in extra virgin olive oil means more polyphenols and antioxidants. These ingredients are neuroprotective and anti-inflammatory. They improve vascular health, strengthen the blood-brain barrier, and clear out the amyloid-β plaques that are linked to Alzheimer’s dementia. Extra virgin olive oil may also help depression. It did so in two controlled trials, and is featured in the Mediterranean style diet for depression.
The Study
This meta-analysis identified five randomized trials (n=747) published between 2013 and 2022, conducted in Spain, Italy, Greece, and the US. Extra virgin olive oil doses ranged widely — from about 2 to 9 tablespoons a day — and follow-up ranged from six months to 6.5 years.
All five studies reported improvement on at least one cognitive scale. Pooled analysis showed statistically significant improvements on the Mini-Mental State Examination (MMSE; MD=0.42), the Clock Drawing Test (MD=0.47), and the Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog; MD=1.45).
Combined analysis of scales assessing global cognitive function (Standardized Mean Difference = SMD, effect size)
Overall, the benefits were small (effect size 0.3) and not in the range considered clinically meaningful for dementia. GRADE rated the evidence as low certainty, and removing any two individual studies rendered the pooled effect non-significant.
Practice Implications
Don’t go promoting extra virgin olive oil as a cure, but this study adds support to its inclusion in a brain-healthy diet.
Extra virgin olive oil also has physical health benefits, and there are two things to know about using it:
- Not for cooking? Though often seen as a delicate oil, the antioxidants actually protect extra virgin olive oil from degradation at high heats. It is stable up to 325-400°F F. In a study of 10 oils, extra virgin olive oil was the least likely to form dangerous polar compounds and trans fats when heated (Guillaume C., et al, Acta Scientific Nutritional Health 2.6 (2018): 02-11).
- Best Products. As with most supplements, product quality varies. Consumer Lab recently tested extra virgin olive oils, and three brands stood out for their health profiles: California Olive Ranch, Lucini Organic, and Life Extension. The first two are available in most grocery stores, but Life Extension is sold through a supplement manufacturer (but it tastes good and is intended for kitchen use). Life Extension had the highest dose of polyphenols.
—Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
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