Older adults who stuck closely to a Mediterranean way of eating had significantly higher blood levels of two mitochondrial microproteins called humanin and SHMOOSE, according to research from the University of Southern California. Both are linked to protecting heart muscle and brain cells from stress and damage.
The findings, published March 9, 2026 in the journal Frontiers in Nutrition, were led by researchers at the USC Leonard Davis School of Gerontology with collaborators at Sapienza University of Rome.
What humanin and SHMOOSE actually do
Humanin and SHMOOSE are tiny peptides encoded inside mitochondria, the energy-producing structures in our cells. Prior research has tied humanin to cardiovascular protection and better insulin sensitivity, while SHMOOSE has been connected to brain health, with one genetic variant linked to higher Alzheimer's risk.
Roberto Vicinanza, instructional associate professor of gerontology at USC and the study's lead author, said the peptides "may act as molecular messengers that translate what we eat into how our cells function and age," according to a statement carried by News-Medical.
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A small study, a specific finding
The analysis was cross-sectional and observational, drawing on 49 patients with a mean age of 78.4 years who were part of a registry of older adults with non-valvular atrial fibrillation. Diet adherence was scored on a validated 9-item Mediterranean diet questionnaire, with high adherence set at 7 to 9 points.
Twenty patients in the high-adherence group had elevated blood levels of both microproteins compared with the 29 in the low-to-medium group. The differences were statistically significant but modest, and the design cannot prove that the diet caused the higher levels.
The foods most linked to the effect
Higher humanin levels tracked with intake of olive oil, fish and legumes. Higher SHMOOSE levels tracked with olive oil intake and a lower share of refined carbohydrates in the diet. Participants with stronger adherence also showed lower markers of oxidative stress, the cellular wear-and-tear implicated in aging and chronic disease.
Senior author Pinchas Cohen, dean of the USC Leonard Davis School, said the peptides "are emerging as key regulators of aging biology" and connect mitochondrial function to conditions such as Alzheimer's and heart disease.
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How it fits the wider evidence
Population studies have consistently linked Mediterranean-style eating to lower rates of cardiovascular disease. The American Heart Association's 2026 dietary guidance explicitly names the Mediterranean pattern, alongside DASH, as a heart-healthy way to eat for people at all levels of cardiovascular risk.
The USC work does not change that guidance. It offers a possible cellular explanation for why the pattern seems to help, and it points to two candidate blood markers that researchers may one day use to gauge whether the diet is doing its job at the molecular level.
What it means for your plate
You do not need to overhaul your kitchen to move in this direction. Regular olive oil in place of butter, fish a couple of times a week, more beans and lentils, and fewer refined-carbohydrate foods like white bread and sugary snacks are the practical building blocks the study points to. People with chronic conditions or on regular medication should talk to their doctor before making large dietary changes.
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