Recent findings provide powerful evidence that adhering to the Mediterranean diet, combined with calorie reduction and increased physical activity, can significantly lower the risk of developing Type 2 diabetes. A large-scale randomized trial conducted in Spain revealed that older adults at risk of diabetes who followed this dietary pattern, cut their caloric intake, and engaged in regular exercise were 31% less likely to develop the disease over a six-year period compared to those who only followed the Mediterranean diet.
The Mediterranean diet emphasizes the consumption of fresh fruits and vegetables, whole grains, nuts, legumes, olive oil, and fish. These ingredients are known for their health benefits and contribute to improved overall well-being. The recent study builds upon earlier research, which indicated that participants adhering to a Mediterranean diet had a 30% reduction in diabetes risk compared to those following a low-fat diet. Notably, the earlier trial did not involve calorie restriction, increased physical activity, or weight loss.
Published in The Annals of Internal Medicine, the study adds to a growing body of research highlighting the importance of dietary patterns, exercise, and weight management in lowering the risk of diabetes and other chronic diseases. Elizabeth Selvin, a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, remarked, "It confirms a lot of what we know." She emphasized that diet and physical activity are critical risk factors for both cardiovascular disease and diabetes, although they can be challenging to study effectively.
This study is significant because it represents a large randomized trial of dietary and behavioral interventions conducted over several years. Randomized trials are crucial as they provide the strongest evidence for causality between interventions and observed outcomes. The role of diet and exercise in reducing diabetes risk was notably established by the 2002 Diabetes Prevention Program, which demonstrated that participants who received education, exercised for a minimum of 150 minutes weekly, and followed a low-calorie, low-fat diet experienced a 58% reduction in their diabetes risk.
Further corroborating the impact of dietary patterns, Selvin's recent research published in Nature Medicine found that a modified DASH diet, rich in fruits, vegetables, and low-fat dairy, helped diabetes patients lower their average blood glucose levels. Additionally, another study published on the same day linked the Mediterranean diet to a decreased risk of Alzheimer’s disease among individuals with a high genetic predisposition.
The Spanish trial followed nearly 5,000 adults aged 55-75 who were overweight or obese and had metabolic syndrome but no prior history of cardiovascular disease or diabetes. Metabolic syndrome includes a range of conditions that elevate the risk of diabetes and other chronic illnesses. Participants in the intervention group received regular counseling from dietitians for six years on how to implement the Mediterranean diet and lower calorie intake. They also engaged in a structured exercise routine, consisting of 45 minutes of brisk walking or equivalent aerobic activity six days a week, along with additional strength and balance training two to three times weekly.
Conversely, the control group received limited education on the Mediterranean diet and met with dietitians less frequently. Both groups were provided with olive oil, a key component of the diet. Over six years, the intervention group lost an average of over 7 pounds and reduced their waist circumference by 1.4 inches, while the control group lost just over 1 pound and 0.1 inches. Remarkably, the weight loss in the intervention group represented only 3.7% of their body weight, which is less than what is typically considered necessary to decrease diabetes incidence.
"The good news is that even a modest change impacted the risk," stated Miguel Ángel Martínez-González, a professor of public health at the University of Navarra and one of the study's investigators. The 31% relative reduction in diabetes risk translates to approximately three fewer cases of diabetes per 100 individuals in the intervention group. Dr. Tirissa J. Reid, an associate professor of medicine at Columbia University Irving Medical Center, noted that while factors such as weight loss likely contributed significantly to the results, the precise impact of each element remains to be clarified.
She emphasized that insulin resistance often develops prior to Type 2 diabetes or prediabetes. A combination of physical activity, high-fiber diets like the Mediterranean diet, and weight loss are effective in mitigating this resistance. Additionally, these factors may help reduce inflammation and oxidative stress, which can damage cells and contribute to diabetes risk.
Dr. Jordi Salas Salvadó, a professor of nutrition at Universitat Rovira i Virgili and senior author of the study, likened the synergy of diet, exercise, and weight loss to an orchestra: "One instrument sounds very good, but when several instruments are playing at the same time, the song is better." Nicole Patience, a registered dietitian at the Joslin Diabetes Center in Boston, highlighted the intensity of the education and support provided during the trial. The prolonged duration of six years helped participants maintain alignment with their goals and achieve lasting behavioral changes.
While it remains unclear how much the support contributed compared to the dietary and activity interventions themselves, replicating this level of contact in real-world settings may present challenges. Additionally, it's important to recognize that the Mediterranean diet may not be suitable for everyone. Nevertheless, the study underscores that even small modifications to diet and the incorporation of exercise can lead to significant improvements in long-term health.
