Higher intake of yogurt linked to lower risk of type 2 diabetes

Researchers are calling for clinical trials to test whether eating yogurt helps avoid type 2 diabetes, after they found higher intake of the dairy food was linked to lower risk of developing the disease.

A new study finds that higher consumption of yogurt is linked to lower risk of developing type 2 diabetes.

Writing in the open access journal BMC Medicine, the team - from Harvard School of Public Health (HSPH) in Boston, MA - explain how they pooled data from three large studies.

The studies had gathered information on dairy food intake and health from over 195,000 health professionals over decades, during which time 15,000 participants developed type 2 diabetes.

The researchers found a high intake of yogurt is associated with a lower risk of developing type 2 diabetes and conclude the findings highlight the importance of including yogurt as part of a healthy diet.

They say their analysis benefited from having a large sample size, high rates of follow up and repeated collection of data on diet, lifestyle and health.

Clinical trials needed to prove whether eating yogurt can protect against type 2 diabetes

However, because the studies the data came from were prospective studies - they gathered information on people's health and diet over time - the researchers could not prove that eating yogurt prevents type 2 diabetes. Only clinical trials can test for such cause and effect links.

Diabetes is a condition where the body cannot convert glucose into energy as well as it should, either because it does not have enough insulin - the hormone that helps glucose enter cells and use it for energy - or because it loses its ability to use it effectively.

Untreated, the condition results in high levels of glucose in the blood, which causes damage to organs.

There are two main types of diabetes: type 1 and type 2. Type 1 diabetes usually begins in childhood and is caused by the immune system's destruction of the insulin-producing cells in the pancreas. Type 2 diabetes - which accounts for 95% of diabetes cases - arises when the body becomes less able to respond to insulin. The pancreas tries to make more and more insulin but eventually this is not enough and glucose levels go up.

A person's risk of developing type 2 diabetes is higher if they have a family history of the condition or if they lead an unhealthy lifestyle. There are around 366 million people living with type 2 diabetes worldwide, and estimates suggest this figure will rise to 522 million by 2030, increasing the pressure on global health systems.

No link between dairy food consumption and type 2 diabetes

In their analysis, the research team at Harvard School of Public Health (HSPH) found no link between total dairy consumption and risk for developing type 2 diabetes.

They then looked at consumption of individual dairy products - for example whole and skimmed milk, cheese and yogurt. They found high consumption of yogurt was linked to a lower risk for developing type 2 diabetes - even after accounting for age, BMI and other chronic disease risk factors.

The researchers then carried out a further analysis. They pooled their results with those of other studies published up to March 2013 that had also looked at links between dairy food consumption and type 2 diabetes.

This further analysis revealed that eating one serving of yogurt a day was linked to an 18% reduced risk of developing type 2 diabetes. One serving is defined as 28 g of yogurt, which is about 2 tablespoons or a quarter of a small pot.

The researchers 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. The consistent findings for yogurt suggest that it can be incorporated into a healthy dietary pattern.

Previous studies have suggested calcium, magnesium and certain fatty acids in dairy products may lower the risk of developing type 2 diabetes. 

Research also suggests the probiotic bacteria in yogurt can help improve the balance of fats and antioxidants in people with type 2 diabetes - so perhaps this also helps lower the risk of developing the disease.

References:

1.  Dairy consumption and risk of type 2 diabetes: 3 cohorts of US adults and an updated meta- analysis, Mu Chen et al., BMC Medicine, published online 25 November 2014, doi:10.1186/s12916-014-0215-1.
2.  BioMed Central news release, accessed 25 November 2014 via EurekAlert.