Yogurts contain probiotics - micro-organisms that play an important role in regulating digestion and intestinal function.
"We found that higher intake of yogurt is associated with a reduced risk of type 2 diabetes, whereas other dairy foods and consumption of total dairy did not show this association," says senior researcher Dr. Frank Hu. "The consistent findings for yogurt suggest that it can be incorporated into a healthy dietary pattern."
The study, published in BMC Medicine and funded by the National Institutes of Health (NIH), sought to assess the association between total and individual types of dairy consumption with the incidence of type 2 diabetes among adults.
Diabetes is a chronic metabolic disease that causes high blood sugar levels. Around 90% of diabetes cases are type 2 diabetes, whereby the body either does not produce enough insulin or suffers from insulin resistance, meaning that the insulin produced is unable to process glucose properly.
In the US, type 2 diabetes affects approximately 26 million people. Worldwide, around 366 million people are affected, with this number estimated to rise to 552 million by 2030.
Participants' dairy consumption and medical history followed in study
For the study, the researchers compiled the results of three large cohort studies. These studies recorded the medical histories and lifestyle habits of health professionals, including dentists, nurses, pharmacists, podiatrists, physicians and vets. A total of 194,519 participants were eligible for the study.
All participants filled out a health and lifestyle questionnaire at the beginning of the study and were followed up every 2 years with further questionnaires. All participants were free from diabetes, cardiovascular disease and cancer at the start of the study, and participants were excluded if they did not include information in their questionnaires about dairy consumption.
Within the three samples, a total of 15,156 cases of type 2 diabetes were identified during the follow-up period. Overall, no association was found between total dairy consumption and type 2 diabetes.
Consumption of individual dairy products such as cheese, skimmed milk, whole milk and yogurt was analyzed. After adjusting their findings for dietary factors and chronic disease factors such as age and BMI, the researchers found an association between high yogurt intake and a lower risk of type 2 diabetes development.
A meta-analysis was then carried out, comparing these findings with those from other studies that had examined the association between dairy products and type 2 diabetes up until March 2013. This analysis found that eating a 28 g serving of yogurt every day was associated with an 18% lower risk of type 2 diabetes developing.
Randomized clinical trials required
Prior to this study, earlier research had suggested that the presence of calcium, magnesium or certain fatty acids within dairy products could lower type 2 diabetes risk. It is now thought that probiotic bacteria in yogurt, with their fat profile and antioxidant status improving qualities, could lower the risk.
"Our study benefited from having such a large sample size, high rates of follow up and repeated assessment of dietary and lifestyle factors," says lead author Mu Chen.
The authors also acknowledge that their study has its limitations. Although large, the cohort samples predominantly consisted of health professionals of European ancestry, suggesting that the findings may not be representative of the whole population. Furthermore, the findings of the study are observational and do not guarantee causation.
"The consistent findings for yogurt suggest that it can be incorporated into a healthy dietary pattern," write the authors. "However, randomized clinical trials are warranted to further examine the causal effects of yogurt consumption as well as probiotics on body weight and insulin resistance."
Medical News Today recently reported on another potential health benefit of yogurt. Probiotic yogurt successfully protects children and pregnant women from the effects of heavy metal poisoning, according to researchers from the Canadian Centre for Human Microbiome and Probiotics.