Fermented Foods and Long-Term Mortality

1. Fermented milk showed the most consistent association with lower mortality.

The analysis of fermented milk and all-cause mortality included more than 1.17 million participants and 133,000 deaths.

Higher consumption was associated with approximately 6% lower all-cause mortality.

It was also associated with approximately 7% lower cardiovascular mortality and 6% lower overall cancer mortality.

All three associations were statistically significant.

2. Yogurt was associated with lower all-cause mortality, but not consistently with cause-specific mortality.

When yogurt was analyzed separately, higher consumption was associated with approximately 7% lower all-cause mortality.

However, the association with cardiovascular mortality did not reach statistical significance. There was also no significant association with overall cancer mortality.

This distinction is important. Findings for fermented milk as a broader category cannot automatically be attributed specifically to yogurt.

3. Different fermented foods showed different associations with mortality.

Higher cheese consumption was associated with approximately 3% lower all-cause mortality. The association was statistically significant, although modest in magnitude.

No significant association was found between cheese consumption and cardiovascular or overall cancer mortality.

Chocolate was associated with lower all-cause and cardiovascular mortality. However, these analyses were based on fewer studies. Heterogeneity was substantial for all-cause mortality, and potential publication bias was identified in the cardiovascular analysis.

These findings therefore require cautious interpretation.

4. Evidence cannot yet be generalized to all fermented foods.

Evidence for miso and fermented bread was too limited to draw firm conclusions about mortality.

Other important fermented food categories could not be adequately evaluated. In particular, fermented vegetables and fermented meats lacked sufficient prospective data for quantitative analysis.

Fermented foods should therefore not be considered a single, nutritionally uniform category.

Fermented foods are increasingly discussed in relation to healthy aging, particularly through their potential effects on the gut microbiome and metabolic health.

This study suggests that fermentation alone does not define the long-term health effects of a food.

Different fermented foods showed different associations with mortality. The strongest and most consistent evidence was observed for fermented milk.

The findings therefore support evaluating fermented foods according to their complete nutritional composition, microbial characteristics and overall role within the diet, rather than assuming that all fermented foods provide the same health benefits.

This meta-analysis provides a broad assessment of fermented food consumption and long-term mortality.

Its strengths include more than three million participants, prospective cohort data and separate analyses of several fermented food categories. The researchers also evaluated study quality and performed sensitivity analyses to test the robustness of the findings.

However, the evidence remains observational.

Dietary intake was largely assessed using self-reported dietary questionnaires. Products, portion sizes, fermentation methods and microbial composition differed between populations. Residual confounding from overall diet, lifestyle and other health-related behaviors cannot be excluded.

The evidence base also differed substantially between individual foods. Fermented milk and cheese were supported by considerably more data than miso, bread or chocolate.

Importantly, fermented food is not synonymous with probiotic food. Some fermented foods contain live microorganisms when consumed. Others contain few or none after heating, baking, roasting or other processing.

Fermentation can also produce metabolites and bioactive compounds that remain present even when live microorganisms do not.

The observed associations therefore do not establish that fermentation itself reduces mortality or extends lifespan.