February 24, 2014 Sophie Langley
Some yoghurts and cheeses may reduce risk of diabetes by one-third
Higher consumption of yoghurt, compared with no consumption, may reduce the risk of new-onset type 2 diabetes by 28 per cent, according to research from the University of Cambridge. Australian experts have leant support to the new UK research findings.
The research, published 5 February 2014 in the journal Diabetologia, found that higher consumption of low-fat fermented dairy products, which include all yoghurt varieties and some low-fat cheese, also reduced the relative risk of diabetes by 24 per cent overall.
“This research highlights that specific foods may have an important role in the prevention of type 2 diabetes and are relevant for public health messages,” said Dr Nita Forouhi, from the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge and lead scientist on the study.
Dairy products are an important source of high quality protein, vitamins and minerals. However, they are also a source of saturated fat, which dietary guidelines currently advise people do not consume in high quantities, instead recommending they replace these with lower fat options.
Type 2 diabetes is common, and the number of people with this serious medical condition is increasing in every country. The International Diabetes Federation has estimated that 382 million people globally had the condition in 2013, with that number rising to 592 million in 2035. Researchers said the potential for its prevention by factors such as the foods we eat was therefore of great interest.
Study method
Previous studies on links between dairy product consumption (high or low fat) and diabetes had inconclusive findings. Thus, the nature of the association between dairy product intake and type 2 diabetes remains unclear, prompting the authors of the University of Cambridge paper to carry out this new investigation using much more detailed assessment of dairy product consumption than was done in past research.
The research was based on the EPIC-Norfolk study, which included more than 25,000 men and women living in Norfolk in the UK. It compared a detailed daily record of all the food and drink consumed over a week at the time of study entry among 743 people who developed new-onset type 2 diabetes over 11 years of follow-up with 3,502 randomly selected study participants. This allowed the researchers to examine the risk of diabetes in relation to the consumption of total dairy products and also types of individual dairy products.
Total dairy consumption compared to low-fat fermented dairy
In the study, total dairy intake in grams per day was estimated and categorised into high-fat and low-fat dairy and by subtype into yoghurt, cheese and milk. Combined fermented dairy product intake (yoghurt, cheese, sour cream) was estimated and also categorised into high- and low-fat. The fat content of whole milk in the UK (3.9% fat) was used as the cut-off for defining high- and low-fat dairy products.
The consumption of total dairy, total high-fat dairy or total low-fat dairy was not associated with new-onset diabetes once important factors like healthier lifestyles, education, obesity levels, other eating habits and total calorie intake were taken into account. Total milk and cheese intakes were also not associated with diabetes risk.
In contrast, those with the highest consumption of low-fat fermented dairy products (such as yoghurt, fromage frais and low-fat cottage cheese) were 24 per cent less likely to develop type 2 diabetes over the 11 years, compared with non-consumers.
When examined separately from the other low-fat fermented dairy products, yoghurt, which made up more than 85 per cent of these products, was associated with a 28 per cent reduced risk of developing diabetes. This risk reduction was observed among individuals who consumed an average of four and a half standard 125g pots of yoghurt per week. The same applied to other low-fat fermented dairy products such as low-fat unripened cheese, including fromage frais and low-fat cottage cheese.
A further finding was that consuming yoghurt in place of a portion of other snacks such as crisps also reduced the risk of developing type 2 diabetes.
While this type of study cannot prove that eating dairy products causes the reduced diabetes risk, researchers said dairy products do contain beneficial constituents such as vitamin D, calcium and magnesium. In addition, fermented dairy products may exert beneficial effects against diabetes through probiotic bacteria and a special form of vitamin K (part of the menaquinone family) associated with fermentation.
The authors acknowledged the limitations of dietary research, which relies on asking people what they eat and not accounting for change in diets over time, but said their study was large with long follow-up, and had detailed assessment of people’s diets that was collected in real-time as people consumed the foods, rather than relying on past memory. The authors said that their study therefore helped to provide robust evidence that consumption of low-fat fermented dairy products, largely driven by yoghurt intake, was associated with a decreased risk of developing future type 2 diabetes.
“At a time when we have a lot of other evidence that consuming high amounts of certain foods, such as added sugars and sugary drinks, is bad for our health, it is very reassuring to have message about other foods like yoghurt and low-fat fermented dairy products, that could be good for our health,” Dr Forouhi said.
‘Not all dairy products are equal’ — Australian expert, Dr Mark Wahlqvist
Responding to the study, Australian experts have said that the study is a reminder that “all dairy products are not equal”.
“That low-fat fermented dairy products, notably yoghurt and some cheeses, are linked to diabetes protection is as much about fermentation as an important feature of the human diet as it is about dairy,” said Mark Wahlqvist, Emeritus Professor of Medicine at Monash University. “It also says that the value of the dietary principle for health extends to within, as well as between, food commodities,” he said.
“We begin life with milk alone, which is testimony to its nutritional complexity and coverage — and that breast milk we ingest supports the development of our gut microbiome (bacterial population),” Professor Wahlqvist said. “But if and when we convert to animal milk, such as cow’s milk, it has historically been fermented. There is a growing body of evidence that this is the safest and healthiest way to have animal milk,” he said.
Need to consider dietary patterns “as a whole” — Australian expert Dr Audrey Tierney
However, Australian experts have also emphasised the importance of considering diet and dietary patterns as a whole.
“In the analysis of this study, the authors found that those with higher estimated dairy product intakes displayed other dietary and lifestyle features such as drinking less alcohol, smoking less and being more physically active, with higher intakes of fibre, fruit and vegetables and fewer processed foods,” said Dr Audrey Tierney, Senior Lecturer in the Department of Dietetics and Human Nutrition at La Trobe University.
“The key message is that it is important to look at the net effect of whole foods, dietary patterns and healthy lifestyle factors and not only isolated foods, nutrient or behaviours,” Dr Tierney said. “However, with increasing prevalence of obesity, diabetes and cardiovascular disease and the reliance on processed, sugar and fat laden foods, opting for a low-fat yoghurt as an alternative to the bag of chips, soft drink or chocolate snack is a better alternative,” she said.
