A new study featuring more than 25,000 female participants has discovered that women who ate a Mediterranean diet are 30 percent less likely to develop type 2 diabetes than women who did not.

The Mediterranean diet is often considered one of the healthiest diets, with an emphasis on healthy fats, like olive oil, nuts, seeds, and fatty fish. The diet also focuses on whole grains, fruits, vegetables, and legumes, making it both a balanced and sustainable diet to follow.

The study, which took place over the course of 20 years, was not intended to analyze specific diets. Participants were simply asked to complete food frequency questionnaires (FFQs), describing what they ate each day and scoring their Mediterranean diet intake from zero to nine: Higher numbers for fruits, veggies, whole grains, legumes, nuts, and fish; mid-range for moderate alcohol intake; and low scores for red or processed meat.

In order to rule out any underlying health conditions, the researchers from Brigham and Women’s Hospital also measured vitals such as cholesterol, insulin resistance, and lipoproteins in the body. With all this data, the researchers looked at the relationship between women’s diets, type 2 diabetes, and other biomarkers that could be responsible for the metabolic disease.

The result? Women who followed a Mediterranean diet at the beginning of the study were 30 percent less likely to develop type 2 diabetes when compared to those who didn’t.

The study, however, isn’t without limitations as most women in the study were white, well-educated, and all worked as health professionals—the researchers drew participants from the Women’s Health Study. The diet was also self-reported, which can hinder accuracy.

Limitations aside, the new study is just the latest in a string of research highlighting the real health benefits that come with following the Mediterranean diet.