Researchers followed over 17,000 Spanish adults for nearly 13 years to see if eating a Mediterranean diet—rich in vegetables, fruits, fish, and olive oil—could help prevent asthma from developing in adulthood. They found that people who most closely followed this eating pattern had about 42% lower chances of developing asthma compared to those who ate this way the least. This is the first major study showing this connection in adult Mediterranean populations, suggesting that what we eat might play an important role in protecting our lungs from asthma.

The Quick Take

  • What they studied: Whether eating a Mediterranean diet (lots of vegetables, fruits, fish, whole grains, and olive oil) could prevent people from developing asthma as adults
  • Who participated: 17,127 Spanish adults who didn’t have asthma at the start of the study, followed for an average of 12.8 years. Participants were mostly of Mediterranean heritage and completed detailed food questionnaires about what they ate
  • Key finding: Adults who most closely followed the Mediterranean diet had a 42% lower risk of developing asthma compared to those who followed it the least. Out of all participants, only 302 people (1.76%) developed asthma during the study
  • What it means for you: Eating more Mediterranean-style foods may help protect you from developing asthma as an adult. However, this doesn’t mean the diet will cure asthma if you already have it, and it’s not a guarantee—it’s one factor among many that influence asthma risk

The Research Details

This was a long-term follow-up study where researchers tracked the same group of people over time. At the beginning, they asked participants detailed questions about what foods they ate using a food frequency questionnaire. Every 2 years for about 13 years, they checked in with participants to see if anyone had developed asthma. Researchers also asked about the same eating habits again after 10 years to see if people’s diets changed.

The researchers created a scoring system called the Mediterranean Diet Score (MDS) that measured how closely each person followed the Mediterranean diet pattern. The score ranged from 0 to 9, with higher scores meaning they ate more Mediterranean-style foods. They then compared asthma rates between people with high scores and low scores, while accounting for other factors that might affect asthma risk.

This approach is powerful because it follows real people in their everyday lives over many years, rather than testing people in a laboratory setting. It helps researchers understand how diet relates to disease in the real world.

This research approach matters because asthma is a common condition that affects millions of adults, and we don’t fully understand all the reasons why some people develop it. By studying a large group of people over a long time, researchers can identify patterns that might help prevent the disease. The Mediterranean diet was chosen because it’s already known to be healthy for the heart and overall health, so testing whether it also protects the lungs is a logical next step.

This study has several strengths: it included a large number of people (over 17,000), followed them for a long time (nearly 13 years), and adjusted for many factors that could affect results like smoking, exercise, and other health conditions. The study was conducted in Spain where the Mediterranean diet is part of the local culture, making the results more realistic. However, the study relied on people remembering and reporting what they ate, which can be imperfect. Also, only 302 people developed asthma, which is a relatively small number for drawing firm conclusions.

What the Results Show

The main finding was clear: people who followed the Mediterranean diet most closely had significantly lower rates of developing asthma. Specifically, those with the highest diet scores (7 or higher out of 9) had about 58% of the asthma risk compared to those with the lowest scores (2 or lower). In statistical terms, this means there was a 42% risk reduction, and this difference was unlikely to have happened by chance.

The relationship appeared to be dose-dependent, meaning the more closely people followed the Mediterranean diet, the lower their asthma risk tended to be. This pattern strengthens the idea that the diet itself, rather than something else, might be responsible for the protection.

The researchers carefully adjusted their analysis for many other factors that could influence asthma risk, including age, sex, smoking status, physical activity, body weight, and family history of asthma. Even after accounting for all these factors, the protective effect of the Mediterranean diet remained significant.

While the abstract doesn’t detail secondary findings, the study measured diet at two time points (baseline and 10 years), which allowed researchers to see how changes in eating habits over time related to asthma risk. The consistency of the Mediterranean diet pattern over time likely strengthened the protective effect.

According to the researchers, this is the first study to find this specific connection in an adult Mediterranean population. Previous research has suggested that diet affects asthma risk in children and adults, but the evidence has been mixed and inconclusive. This study provides stronger evidence by following a large group of adults for many years and finding a clear pattern. The Mediterranean diet has already been shown to protect against heart disease, diabetes, and other chronic conditions, so finding a protective effect against asthma adds to the growing evidence that this eating pattern supports overall health.

The study has several important limitations to consider. First, participants self-reported whether they had asthma, which means some cases might have been missed or misdiagnosed. Second, people reported what they ate through questionnaires, which relies on memory and can be inaccurate. Third, the study was conducted in Spain with people of Mediterranean heritage, so the results might not apply equally to other populations or countries. Fourth, only 1.76% of participants developed asthma, which is a relatively small number and means the results could be affected by chance more easily. Finally, this study shows an association between diet and asthma, but it cannot prove that the diet directly causes the lower asthma risk—other unmeasured factors could be involved.

The Bottom Line

Based on this research, eating a Mediterranean-style diet appears to be a reasonable approach for adults who want to reduce their asthma risk. This means emphasizing vegetables, fruits, whole grains, legumes, fish, and olive oil while limiting red meat and processed foods. However, this finding should be considered one piece of a larger healthy lifestyle picture that includes not smoking, regular exercise, and maintaining a healthy weight. The evidence is moderately strong but not definitive, so this should complement—not replace—medical advice from your doctor.

This research is most relevant for adults without asthma who want to prevent it from developing, particularly those with family history of asthma or other risk factors. It may also interest people with asthma who want to explore dietary approaches alongside their medical treatment. However, this study doesn’t address whether the Mediterranean diet helps people who already have asthma, so those individuals should focus on their doctor’s treatment plan. The findings are most directly applicable to people living in Mediterranean regions or those who can realistically adopt this eating pattern.

Realistic expectations are important here. The study followed people for an average of 12.8 years, so any protective benefits would likely develop gradually over months and years, not weeks. If you’re adopting this diet to reduce asthma risk, you should think of it as a long-term lifestyle change rather than a quick fix. You might notice other health benefits like improved energy or better digestion within weeks or months, but the asthma prevention benefit would take much longer to assess.

Want to Apply This Research?

  • Track daily servings of Mediterranean diet components: vegetables (goal 3+ servings), fruits (goal 2+ servings), whole grains (goal 3+ servings), fish (goal 2-3 times weekly), and olive oil use (goal 2-3 tablespoons daily). Create a simple daily checklist to monitor adherence to these food groups
  • Start by adding one Mediterranean element to each meal: add extra vegetables to lunch, use olive oil for cooking, swap white bread for whole grain, or include fish twice weekly. Build gradually rather than overhauling your entire diet at once. Use the app to set weekly goals like ’try one new fish recipe’ or ‘buy three new vegetables at the market’
  • Beyond food tracking, monitor respiratory health by noting any changes in breathing, shortness of breath, or asthma symptoms (if applicable). Track this monthly alongside diet adherence to look for patterns. Also monitor related health markers like energy levels, weight, and overall wellness to see the broader benefits of dietary changes

This research suggests an association between Mediterranean diet adherence and lower asthma risk in adults, but it does not prove cause-and-effect. The study was observational and relied on self-reported data. If you have asthma or respiratory concerns, consult your healthcare provider before making significant dietary changes or adjusting any asthma medications. This information is not a substitute for medical advice, diagnosis, or treatment. Individual results may vary based on genetics, environment, and other health factors not measured in this study.