Three-City Study: Diet Patterns and 10-Year Mortality in 8,937 French Elderly

This prospective cohort analysis from the Three-City Study tracked 8,937 community-dwelling French adults aged 65 and older for an average of 9 years to test whether dietary habits predict all-cause mortality. Published in the British Journal of Nutrition, the analysis found that intensive olive oil use was associated with 28% lower mortality in women, with parallel benefits from higher fruit and vegetable intake and regular fish consumption. Daily meat consumption was associated with 12% higher mortality.

Why This Study Matters

Dietary recommendations for elderly adults have historically been driven by clinical trials in middle-aged populations and extrapolated upward. But the relationship between diet and mortality may differ in older adults -- both because the underlying biology of aging changes how food interacts with health, and because the practical question shifts from preventing chronic disease over decades to maintaining function and survival over years.

The Three-City Study was designed to study aging directly. It enrolled adults aged 65 and older from three French cities (Bordeaux, Dijon, Montpellier) starting in 1999, captured baseline dietary intake, and followed participants prospectively for mortality and major health outcomes. This 2016 analysis used the full mortality follow-up to test associations between dietary patterns and risk of death.

The result was a multi-component dietary signal: higher fruit and vegetable consumption, regular fish intake, and intensive olive oil use (in women specifically) were each independently associated with lower all-cause mortality, after adjustment for socio-demographic and health-status confounders.

How It Was Designed

The basics: 8,937 community-dwelling adults aged 65+ at baseline (mean age 74.2 years; 60.7% women), 9 years of average follow-up, three French cities. During follow-up, 2,016 deaths were recorded.

Dietary intake was assessed at baseline using a brief food frequency questionnaire that captured consumption frequency for major food groups -- fruits, vegetables, fish, meat, dairy, and various fats including olive oil. Olive oil use was classified into three categories matching prior Three-City analyses: no use, moderate use (cooking OR dressing), and intensive use (cooking AND dressing). Fruit and vegetable intake was combined into a frequency variable; fish consumption was classified as occasional vs. regular.

Cox proportional-hazards models were adjusted for sex, study center, socio-demographic variables (age, education, income, marital status), and health status indicators (history of cardiovascular disease, diabetes, hypertension, cancer, depressive symptoms, BMI, and number of medications). Sex-stratified analyses were conducted because preliminary models suggested sex-specific patterns in the olive oil association.

Cause-of-death classification followed ICD-10 codes; this analysis focused on all-cause mortality as the primary endpoint, with the rationale that in older adults, total survival is the most clinically meaningful outcome.

What They Found

The multivariable-adjusted hazard ratios for the major dietary exposures were:

Exposure	Hazard Ratio (95% CI)	Risk Reduction	What It Measures
Intensive olive oil, women	0.72 (0.60-0.85)	28% lower	All-cause mortality, intensive vs. never users
Moderate olive oil, women	0.80 (0.68-0.94)	20% lower	All-cause mortality, moderate vs. never users
High fruit & vegetable intake	0.90 (0.82-0.99)	10% lower	All-cause mortality, highest vs. lowest intake
Regular fish consumption	0.89 (0.81-0.97)	11% lower	All-cause mortality, regular vs. occasional fish
Daily meat consumption	1.12 (1.01-1.24)	12% higher	All-cause mortality, daily vs. less frequent meat

Green indicates a favorable direction; red indicates higher mortality risk. The olive oil association was statistically significant in women only. Fruit/vegetable and fish associations held across both sexes; the meat association applied to the full cohort.

Reading the Results

The findings group into four threads.

Olive oil in women (28% lower mortality with intensive use, 20% with moderate use). The graded dose-response from never -> moderate -> intensive use is consistent with a true dietary effect rather than a binary lifestyle marker. The sex-specific pattern -- statistically significant in women but not men -- echoes the EPICOR analysis, which focused exclusively on Italian women and found a 44% reduction in CHD risk with high olive oil intake. The researchers note that men in the Three-City cohort had higher absolute olive oil intake overall and a narrower range of variation, which may have reduced statistical power to detect a dose-response in men specifically.

Fruit and vegetable intake (10% lower mortality). A modest but statistically significant signal that's consistent with dozens of prior cohort analyses. The 10% magnitude is at the lower end of what major plant-food cohorts have reported, reflecting the older study population (where overall mortality is dominated by aging biology rather than diet alone) and the relatively narrow range of intake within a French elderly population.

Regular fish consumption (11% lower mortality). Aligns with broader literature on omega-3 fatty acids and cardiovascular health. Regular fish consumption in this French cohort would typically include fatty fish (mackerel, sardines, salmon) that contribute meaningful EPA and DHA intake.

Daily meat consumption (12% higher mortality). The only directionally unfavorable signal in the analysis. The 12% increase is modest but statistically significant. The researchers were careful to note that the effect was driven by daily consumption specifically -- not by occasional meat eating -- and that the effect was robust to adjustment for total energy intake, suggesting it isn't simply a marker of overeating.

What Didn't Change

The analysis found no significant association between overall dietary diversity (measured as a diet diversity score) and mortality, nor between consumption of various other fats and mortality after adjusting for olive oil specifically. The olive oil signal in men did not reach conventional statistical significance, though the point estimates trended in the same direction as for women.

The study is observational, not interventional. It cannot prove that consuming more olive oil or eating less meat causes lower mortality. The dietary assessment was a brief food frequency questionnaire administered only at baseline, which doesn't capture changes in intake across the 9-year follow-up. Residual confounding by overall lifestyle, socioeconomic status, or unmeasured health behaviors remains possible.

Broader Context

This Three-City mortality analysis complements the cohort's prior cognitive findings (Berr et al., 2009) and stroke findings (Samieri et al., 2011), which used the same olive oil classification scheme. The signal is internally consistent: the same intensive-use pattern that predicts lower stroke incidence and slower cognitive decline also predicts lower all-cause mortality.

The findings align with the broader olive oil mortality literature. EPIC-Spain (Buckland et al., 2012, AJCN) reported a 26% reduction in all-cause mortality and a 44% reduction in cardiovascular mortality in the highest quartile of olive oil intake. The Harvard pooled cohort (Guasch-Ferre et al., 2022) reported a 19% reduction in cardiovascular mortality and a 29% reduction in neurodegenerative mortality with more than 7 g/day of olive oil intake in a non-Mediterranean U.S. population.

The 2011 European Food Safety Authority opinion (Regulation 432/2012) authorized a health claim for olive oil polyphenols and protection of blood lipids from oxidative damage at a daily intake of 5 mg of hydroxytyrosol and its derivatives. The Three-City Study did not measure polyphenol intake directly, but the intensive-use pattern would typically deliver well above the EFSA threshold.

What this cohort adds is a 10-year mortality analysis in community-dwelling French elderly, with internally consistent signals across stroke, cognition, and total survival from the same dietary classification.

Related Research

Continue exploring olive oil and polyphenol science:

• Three-City Study: Intensive Olive Oil Use Linked to 41% Lower Stroke Risk
• Three-City Study: Olive Oil Use Linked to Better Cognitive Function in Elderly
• Italian Cohort: Olive Oil Linked to Lower Cancer, CV and All-Cause Mortality

Source: View the original study on PubMed

Olivea's Dosage

The Three-City Study did not specify a gram-per-day threshold; the benefit emerged in adults who used olive oil for both cooking and dressing -- a structural pattern rather than a precise dose. A single tablespoon of Olivea extra virgin olive oil delivers approximately 14 grams. Each Olivea capsule delivers over 20 mg of hydroxytyrosol per serving in an EVOO matrix; our most recent third-party certificate of analysis confirmed 23.5 mg per capsule.

We share this research for transparency. This is an independent study -- we did not fund it, design it, or conduct it.

Editorial Information

Research note. This article summarizes third-party research published in a peer-reviewed journal. Olivea did not conduct or fund the study. Findings reflect the cited paper only and do not establish efficacy of Olivea products.

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