Even if this probably is a good news story, an initial caveat is justified. Establishing a causal link between consumption of an individual food product, like yoghurt, and a specific disease is fraught with challenges. It could be a statistical anomaly or covariant factors that were responsible for the effects but not possible to be eliminated during the statistical analysis. In this study, also the authors point out that to confirm the findings controlled studies would be necessary.
With this caveat out of the way, researchers from Harvard School of Public Health found that a high intake of yoghurt seemed to be associated with an 18% lower risk of developing type 2 diabetes. If true, it shows the benefit of having yoghurt as part of a healthy diet.
Facts about the disease
Type 2 diabetes is a chronic condition that occurs when the body doesn’t produce enough insulin, or the body’s cells develop resistance to insulin. The condition has a strong genetic background and is also often associated with modifiable lifestyle risk factors like an unhealthy diet and lack of exercise. Type 2 diabetes usually develops in middle age adults but is increasingly occurring in younger age groups. The Harvard researchers pointed out that about 366 million people are affected by type 2 diabetes worldwide and it is estimated that this will increase to 552 million people by 2030, which puts pressure on global healthcare systems.
The disease develops over a long period of time with a progressive insulin resistance. As insulin is increasingly ineffective at managing the blood glucose levels, the pancreas responds by producing greater and greater amounts of insulin wearing the insulin-producing cells out. By the time someone is diagnosed with type 2 diabetes, they have lost 50 – 70% of their insulin-producing cells. This means type 2 diabetes is a combination of insulin resistance and not enough insulin.
It might be possible to significantly slow or even halt the progression of the condition by increasing the amount of physical activity and adopting a healthier diet. And here yoghurt might be a part of a healthy diet.
Facts about the study
The Harvard researchers pooled the results of three large prospective cohort studies that have been following the medical history and lifestyle habits of health professionals in the USA for different purposes. At the beginning participants had been asked to complete a questionnaire to gather baseline information on diet, lifestyle and occurrence of chronic disease. Participants were followed up every two years for 16-30 years depending on cohort with a follow-up rate of more than 90 per cent.
In this particular analysis of the cohorts results, the researchers excluded participants with diabetes, cardiovascular disease or cancer at baseline as well as lack of response to the question on dairy consumption as this was the target for the analysis. This resulted in a coverage of almost 195,000 remaining participants aged between 25 to 75 years for the analysis.
Study benefits included the large sample size, high rates of follow up and repeated assessment of dietary and lifestyle factors.
What did they find?
Within the three cohorts 15,156 cases of type 2 diabetes were identified during the follow-up period. While adjusting for chronic disease risk factors such as age and BMI as well as dietary factors, the researchers found that total dairy consumption had no association with the risk of developing type 2 diabetes. They then looked at consumption of individual dairy products, such as skimmed milk, cheese, whole milk and yoghurt and found that high consumption of yoghurt was associated with a lower risk of developing type 2 diabetes.
To confirm their results the authors conducted a meta-analysis, incorporating their results with results from a few other published studies that also investigated the association between dairy products and type 2 diabetes. Overall they concluded that consumption of one 28g serving of yoghurt per day was associated with an 18% lower risk of type 2 diabetes.
So overall some good news.
What to think of the findings?
While an 18% improvement might not sound that much every bit helps. It is extremely rare to find any food that can have a major impact on a particular health condition. What comes to mind is vitamin C rich foods like oranges that can fully protect against scurvy, but not much else. An overall healthy diet is more important than individual food components and of course yoghurt can be part of that healthy diet.
There are other support for yoghurt consumption. In 1904, four years before he jointly won the Nobel Prize in Physiology or Medicine for his research in immunology, Professor Elie Metchnikoff gave a public lecture in Paris. He suggested that beneficial healthy bacteria could be cultivated in the gut by eating yoghurt or other types of sour milk. He had surveyed 36 countries and found that more people lived to the age of 100 in Bulgaria, a high yoghurt consuming country, than anywhere else.
Later research has shown that probiotic bacteria found in yoghurt improves fat profiles and antioxidant status in people with type 2 diabetes and suggest this could have a risk-lowering effect in developing the condition.
You be the final judge, but a little yogurt every day is probably not a bad thing!
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