# Mediterranean diet adherence is associated with mitochondrial microproteins Humanin and SHMOOSE; potential role of the Humanin–Nox2 interaction in cardioprotection

## TL;DR

This study shows that following a Mediterranean diet is linked to higher levels of mitochondrial microproteins Humanin and SHMOOSE, which may help protect the heart.

## Contribution

The study identifies Humanin and SHMOOSE as potential biomarkers of Mediterranean diet adherence and suggests a novel cardioprotective mechanism involving Humanin–Nox2 interaction.

## Key findings

- High Mediterranean diet adherence is associated with increased plasma levels of Humanin and SHMOOSE.
- Humanin levels are inversely related to markers of oxidative stress like sNox2-dp and 8-iso-PGF2α.
- Dietary components like olive oil, fish, and legumes correlate with higher levels of Humanin and SHMOOSE.

## Abstract

The health benefits of the Mediterranean Diet (Med-Diet) have been demonstrated in observational studies and randomized controlled trials. Emerging evidence suggests that the biological effects of the Med-Diet may be mediated by the modulation of mitochondrial function. Human mitochondrial DNA (mtDNA) encodes microproteins, which have been shown to regulate aging, cardiometabolic functions, and neuroprotection.

To investigate Humanin and SHMOOSE (Small Human Mitochondrial ORF Over SErine tRNA), as potential mitochondrial biomarkers of Med-Diet adherence and their associations with markers of oxidative stress.

Cross-sectional analysis of 49 patients (mean age 78.4 ± 8.7 years; 57% female) selected from an observational study of non-valvular atrial fibrillation (AF) conducted at the Atherothrombosis Center of Sapienza University of Rome. Patients were categorized into low-medium (0–6) and high (7–9) adherence to the Med-Diet based on the 9-item Med-Diet questionnaire. Oxidative stress was evaluated by measuring soluble Nox2-derived peptide (sNox2-dp) and plasma 8-iso-prostaglandin F2α (8-iso-PGF2α) using enzyme-linked immunosorbent assays (ELISA). Circulating Humanin and SHMOOSE levels were measured using an in-house sandwich ELISA.

High Med-Diet adherence was observed in 20 patients (40.8%), while 29 patients (59.2%) had low-medium adherence. Patients with high adherence exhibited higher plasma levels of SHMOOSE (p = 0.046) and Humanin (p = 0.045). The analysis of the dietary components of the Med-Diet revealed higher levels of SHMOOSE with olive oil consumption (p = 0.020) and low intake of refined bread (p = 0.029), while Humanin positively correlated with olive oil (p = 0.0069), fish (p = 0.038), and legumes (p = 0.0282). Additionally, Humanin was inversely associated with sNox2-dp (p = 0.019), which remained significant after adjusting for sex and BMI (B = −0.010; β = −0.302; p = 0.040), and 8-iso-PGF2α (p = 0.049).

This study indicates (i) a positive association between adherence to the Med-Diet and circulating levels of mitochondrial microproteins SHMOOSE and Humanin supporting their role as potential mediators of Med-Diet benefits; (ii) a putative crosstalk between Humanin signaling and Nox2 activity, suggesting a novel cardioprotective mechanism of the Med-Diet. Collectively, these findings support mitochondrial microproteins as promising biomarkers for tailoring nutritional strategies for healthy aging. Further studies are warranted to elucidate the underlying mechanisms and determine the causal nature of these associations.