The new data, published in BMC Medicine, pooled the results of three prospective cohort studies that followed the medical history and lifestyle habits of health professionals – finding that consumption of one 28g serving of yogurt per day was associated with an 18 per cent lower risk of type 2 diabetes.
Previous research has proposed that calcium, magnesium, or specific fatty acids present in dairy products may lower the risk of type 2 diabetes, while it has also been suggested that certain probiotic bacteria found in yogurt could improve fat profiles and antioxidant status in people with type 2 diabetes.
"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,” commented senior researcher Frank Hu from the Harvard School of Public Health.
“The consistent findings for yogurt suggest that it can be incorporated into a healthy dietary pattern."
However, the team noted that in order to confirm this observation, and investigate whether or not yogurt consumption is causal in the lowering of risk, randomised controlled trials are needed.
The Harvard-based research team analysed data from three previous long-term studies - these studies were the Health Professionals' Follow-up Study (HFPS), which included 51,529 US male dentists, pharmacists, vets, osteopathic physicians and podiatrists, aged from 40 to 75 years; Nurses' Health Study (NHS), which began in 1976, and followed 121,700 female US nurses aged from 30 to 55 years; and Nurses' Health Study II (NHS II), which followed 116,671 female US nurses aged from 25 to 42 years beginning in the year 1989.
At the beginning of each cohort study, participants completed a questionnaire to gather baseline information on lifestyle and occurrence of chronic disease. Participants were then followed up every two years with a follow-up rate of more than 90%.
Participants were excluded from the analysis if they had diabetes, cardiovascular disease or cancer at baseline. People were also excluded if they did not include any information about dairy consumption.
This left a total of 41,497 participants from HPFS, 67,138 from NHS and 85,884 from NHS II.
"Our study benefited from having such a large sample size, high rates of follow up and repeated assessment of dietary and lifestyle factors,” noted Mu Chen, first author of the study.
Within the three cohorts 15,156 cases of type 2 diabetes were identified during the follow-up period.
The team reported that the total dairy consumption had no association with the risk of developing type 2 diabetes, however, when they then looked at consumption of individual dairy products - such as skimmed milk, cheese, whole milk and yogurt – they found that yoghurt consumption was associated with a lower risk of type 2 diabetes.
This association remained after adjusting for chronic disease risk factors such as age and BMI as well as dietary factors, said Hu and his colleagues.
The team then conducted a meta-analysis, incorporating their results and other published studies that investigated the association between dairy products and type 2 diabetes. This analysis found that consumption of one 28g serving of yogurt per day was associated with an 18 per cent lower risk of type 2 diabetes.
Source: BMC Medicine
Published online, open access, doi:10.1186/s12916-014-0215-1
"Dairy consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta-analysis"
Authors: Mu Chen, Qi Sun, et al