Ibsen et al. ( Reference Ibsen, Laursen and Lauritzen 1 ) conducted a prospective study to investigate the association between dairy product subgroups and subsequent risk of type 2 diabetes. The hazard ratio (HR) of low-fat yogurt products against whole-fat yogurt products for incident type 2 diabetes was 1·17 (95 % CI 1·06, 1·29). In addition, HR of whole-fat yogurt products against low-fat milk, whole-fat milk and buttermilk products for the incident type 2 diabetes were 0·89 (95 % CI 0·83, 0·96), 0·89 (95 % CI 0·82, 0·96) and 0·89 (95 % CI 0·81, 0·97), respectively. The authors concluded that intake of whole-fat yogurt products in place of low-fat yogurt products, low-fat milk, whole-fat milk and buttermilk were preventive nutrients for incident type 2 diabetes. I have some concerns about their study.
First, the authors recommended whole-fat yogurt products for the prevention of type 2 diabetes. In contrast, O’Connor et al. ( Reference O’Connor, Lentjes and Luben 2 ) conducted a nested case–cohort study to investigate the association between total dairy product intake, several types of dairy product intake and the risk of developing incident type 2 diabetes. Low-fat fermented dairy product intake, especially yoghurt intake, was inversely associated with incident type 2 diabetes, presenting an HR of 0·72. In addition, high-fat dairy products were not associated with incident type 2 diabetes. Although the study design differed, inconsistent results should be specified by further study.
Second, Guasch-Ferré et al. ( Reference Guasch-Ferré, Becerra-Tomás and Ruiz-Canela 3 ) also recognised that whole-fat yogurt intake was associated with a lower risk of type 2 diabetes, although the intake of animal fat was associated with higher incident type 2 diabetes. As the type of dietary fat had different risks for type 2 diabetes, the association between whole-fat yogurt products and lower incident type 2 diabetes should be analysed by a meta-analysis of prospective studies.
Finally, there is a report that the association of dairy products and incident prediabetes or diabetes varied by the type of dairy product and by the baseline glycaemic status( Reference Hruby, Ma and Rogers 4 ), although there is an inverse dose–response relationship between the amount of high-fat dairy products and incident type 2 diabetes. From the biological mechanism, the intake of high fat from dairy products, not from meat, would be protective for type 2 diabetes( Reference Ericson, Hellstrand and Brunkwall 5 ).
Acknowledgements
I want to express my heartfelt thanks to members of the Department of Public Health, Nippon Medical School, for their technical support.
This research received no specific grant from any funding agency, commercial or not-for-profit sectors.
The corresponding author wrote a draft and revised it.
The author declares that there are no conflicts of interest.
