Tiny mitochondrial proteins may explain the health benefits of the Mediterranean diet

A recent study published in the journal Frontiers in Nutrition suggests that the health benefits of the Mediterranean diet might be driven by tiny proteins produced inside the energy-generating structures of our cells. Researchers discovered that older adults who closely follow this way of eating have higher levels of two microscopic proteins that protect against heart disease and cognitive decline. These results offer a new biological explanation for how a diet rich in olive oil, fish, and legumes promotes healthy aging at a cellular level.

To understand the mechanics behind these physiological benefits, it helps to look inside the human cell. Most people are familiar with mitochondria, which act as microscopic power plants that generate the energy needed for cellular survival. Mitochondria contain their own unique set of genetic instructions that are completely separate from the main DNA housed in the cell nucleus.

For many years, geneticists believed certain small sections of this mitochondrial DNA served no practical purpose. During the Human Genome Project, researchers largely overlooked these tiny genetic sequences because they appeared too short to encode functional molecules. Scientists eventually realized that these genetic codes actually produce active molecules called mitochondrial microproteins.

These microproteins are much smaller than standard cellular proteins but perform essential tasks in regulating cellular health and responding to stress. Two specific microproteins, known as Humanin and SHMOOSE, have attracted attention for their powerful protective properties. Previous research linked Humanin to improved insulin sensitivity, cellular survival, and defense against cardiovascular disease.

Similarly, SHMOOSE appears to help protect brain cells from the type of structural damage often seen in Alzheimer’s disease. Because mitochondria are deeply involved in how the body processes nutrients, researchers suspected that everyday eating habits might influence the production of these protective microproteins. Roberto Vicinanza, an instructional associate professor of gerontology at the University of Southern California, led a team to investigate this possibility.

Pinchas Cohen, dean of the University of Southern California Leonard Davis School of Gerontology, served as the senior author on the project. Vicinanza and his colleagues wanted to see if people who followed a traditional Mediterranean diet had distinct levels of Humanin and SHMOOSE in their blood. The Mediterranean diet emphasizes whole grains, fruits, vegetables, legumes, and olive oil while limiting red meat and heavily processed carbohydrates.

Medical professionals widely recommend this dietary pattern to help prevent metabolic disorders and maintain overall cardiovascular function. The research team also aimed to measure markers of oxidative stress, a biological process that damages cells and accelerates aging. As mitochondria generate energy, they naturally produce reactive oxygen molecules as a byproduct, much like a car engine produces exhaust.

When the body produces too many of these reactive molecules, often driven by an enzyme known as Nox2, it leads to oxidative stress. The investigators hypothesized that a healthy diet might increase microprotein levels, which could in turn help suppress this damaging oxidative activity.

To test these ideas, the researchers recruited 49 older adults from a cardiovascular clinic in Rome, Italy. The participants had an average age of roughly 78 years and were originally part of a larger observational program focused on heart rhythm disorders. Medical staff asked the patients to complete a standardized dietary questionnaire detailing their typical eating habits at home.

The questionnaire awarded points based on how frequently participants consumed staple foods like olive oil, fish, fruits, and vegetables. Based on their final scores, the researchers divided the patients into two distinct groups. One group demonstrated high adherence to the Mediterranean diet, while the other group showed low to medium adherence.

The clinical team then collected fasting blood samples from all participants to measure circulating levels of Humanin and SHMOOSE. They also analyzed the blood for two specific chemical markers that indicate the presence of cellular oxidative stress. The laboratory staff evaluating the samples did not know which dietary group each patient belonged to, which helped prevent observational bias during the testing phase.

When the researchers compared the blood test results with the dietary scores, they noticed a clear physiological pattern. The patients who strictly followed the Mediterranean diet had elevated concentrations of both Humanin and SHMOOSE in their bloodstream. Conversely, the group with lower dietary adherence exhibited comparatively lower levels of these microscopic proteins.

The results were not statistically significant when comparing basic lipid profiles, such as total cholesterol and triglycerides, between the two groups. However, the differences in microprotein concentrations stood out clearly across the patient cohort.

The investigators then analyzed individual food components to see which items had the strongest physiological effect. They found that patients who consumed at least one tablespoon of olive oil daily and ate minimal amounts of refined white bread had the highest levels of SHMOOSE. Meanwhile, elevated Humanin levels appeared in patients who regularly consumed olive oil, fish, and a few servings of legumes each week.

“These microproteins may act as molecular messengers that translate what we eat into how our cells function and age,” Vicinanza said. He noted that this newly observed biological pathway helps explain why this specific dietary pattern is so effective at maintaining physical health over time.

In addition to the microprotein increases, the researchers observed an inverse relationship between Humanin and Nox2, the enzyme responsible for cellular damage. Patients with higher levels of circulating Humanin had lower levels of Nox2 activity and fewer markers of overall oxidative stress. This inverse correlation suggests that Humanin might actively block the enzyme from producing harmful oxygen molecules in the bloodstream.

Cohen pointed out that these tiny proteins are emerging as key regulators of aging biology. “They connect mitochondrial function to diseases like Alzheimer’s and heart disease and now, potentially, to nutrition,” Cohen said. The researchers suspect that the diet provides a dual benefit by offering natural plant-based antioxidants while simultaneously boosting protective microproteins.

While the data provide a fresh perspective on nutrition and cellular health, the authors acknowledge a few limitations to their work. The project relied on an observational design, meaning it cannot definitively prove that the diet directly caused the changes in microprotein levels. The relatively small number of participants and their specific age range also mean the results might not automatically apply to a younger, broader population.

Additionally, the dietary questionnaire provided a simplified snapshot of eating habits rather than a comprehensive log of daily food intake. The researchers did not track other lifestyle factors like daily physical activity, which can also influence mitochondrial function and overall metabolic health. The participants also had moderate underlying health conditions, which might have influenced how their bodies naturally produced these proteins.

Future research will need to involve controlled dietary interventions to confirm these initial observations. In these upcoming projects, scientists would actively change the diets of participants over a set period and measure the resulting fluctuations in microprotein levels. If clinical trials replicate the current findings, medical professionals could eventually use Humanin and SHMOOSE as simple blood markers to track how well a patient is adhering to nutritional advice.

Ultimately, the investigators hope to translate these biochemical discoveries into personalized nutrition plans that slow the aging process. By understanding exactly how specific foods interact with the cellular mitochondria, doctors might one day prescribe highly tailored diets to maximize cellular protection. Until then, the research offers yet another biological reason to prioritize whole grains, olive oil, and legumes at the dinner table.

The study, “Mediterranean diet adherence is associated with mitochondrial microproteins Humanin and SHMOOSE; potential role of the Humanin–Nox2 interaction in cardioprotection,” was authored by Roberto Vicinanza, Vittoria Cammisotto, Junxiang Wan, Kelvin Yen, Francesco Violi, Pasquale Pignatelli, and Pinchas Cohen.