Randomized controlled trials have established the beneficial effect of a healthy diet in the treatment of cardiometabolic disorders. Healthy diet recommendations are based on this evidence (1). However, limited evidence is available on whether individuals with these conditions actually follow such dietary recommendations in an effective way, that is, by making long-term changes in their dietary behavior.
In this cohort study of 4,703 participants (mean age 49.5 years, 27.8% women) from the Whitehall II study (www.ucl.ac.uk/whitehallII), we screened participants for type 2 diabetes (T2D), metabolic syndrome (MetS), and obesity and then followed changes in diet with follow-up surveys. Participants were informed that they had diabetes or were obese but were not informed if they had MetS, and no dietary advice was given. Both prevalent (in 1991/1993) and new-onset cases (occurrence between 1991/1993 and 2002/2004) of T2D (according to the World Health Organization criteria ), MetS (the National Cholesterol Education Program Adult Treatment Panel III criteria definition), and obesity (BMI ≥30 kg/m2) were considered, as described elsewhere (3). Changes in diet were determined using repeated measures of the Alternative Healthy Eating Index (AHEI) over an 11-year follow-up (from 1991/1993 to 2002/2004). Given the dietary intake data collected with a validated 127-item food-frequency questionnaire, AHEI was created by summing its nine component scores (fruits, vegetables, ratio of white to red meat, trans fat, ratio of polyunsaturated to saturated fat, total fiber, nuts and soy, alcohol consumption, and long-term multivitamin use). Improvement (from below to above median AHEI score) and deterioration (from above to below median AHEI score) in diet over the follow-up was determined based on median value of 50.5 points.
Figure 1 shows that after adjustment for age, sex, ethnicity, socioeconomic status, marital status, total energy intake, smoking, alcohol consumption, and physical activity, neither prevalent nor new-onset T2D, MetS, or obesity were associated with improvements in diet among participants with an unhealthy diet at baseline. Among participants with a healthy diet at baseline, the likelihood of deterioration in diet was higher in those with prevalent T2D and obesity and in those with new-onset MetS compared with those without.
In conclusion, being alerted to the presence of diabetes or its risk factor obesity does not appear to change dietary behavior in an observational framework where no dietary advice was given. Similarly, no change in diet was observed in people with MetS. These results are concordant with studies showing no evidence of sustained change in other lifestyle factors, such as alcohol consumption and physical activity, in participants experiencing chronic diseases (4) and with studies reporting high rates of smoking after myocardial infarction (5). We have previously shown that good adherence in AHEI is related to an almost twofold higher odds of reversing MetS, suggesting that reversal of cardiometabolic risk factors via changes in behavior is possible (3). Given this and the substantial estimated cost of nonadherence to dietary guidelines to society, dietary consultation is warranted in participants with metabolic disorders, such as diabetes, MetS, or obesity. In addition, further research is needed to identify effective interventions to ensure patients’ adherence to dietary recommendations.
Acknowledgments. The authors thank all of the participating civil service departments and their welfare, personnel, and establishment officers; the British Occupational Health and Safety Agency; the British Council of Civil Service Unions; all participating civil servants in the Whitehall II study; and all members of the Whitehall II study team. The Whitehall II study team comprises research scientists, statisticians, study coordinators, nurses, data managers, administrative assistants, and data entry staff, who make the study possible.
Funding. The Whitehall II study has been supported by grants from the Medical Research Council (K013351); the British Heart Foundation (PG/11/63/29011 and RG/13/2/30098); the Health and Safety Executive; the U.K. Department of Health; the National Heart, Lung, and Blood Institute (R01HL036310) and the National Institute on Aging of the National Institutes of Health (R01AG013196 and R01AG034454); and the Economic and Social Research Council (ES/J023299/1). T.N.A. is supported by the Economic and Social Research Council and grants allocated by Languedoc Roussillon District (Chercheur d′Avenir and Aide à la Recherche en Partenariat avec les Entreprises). M.J.S. is supported by the British Heart Foundation. M.K. is supported by the Medical Research Council (K013351) and NordForsk and has a professorial fellowship from the Economic and Social Research Council. The University of Edinburgh Centre for Cognitive Ageing and Cognitive Epidemiology is funded as part of the joint U.K. research council call for Lifelong Health and Wellbeing.
The funding organization or sponsor had no role in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; the preparation, review, or approval of the manuscript; or the decision to submit the manuscript for publication.
Duality of Interest. No potential conflicts of interest relevant to this article were reported.
Author Contributions. T.N.A. and M.K. designed the research, analyzed the data, wrote the first draft, and made critical revisions of the manuscript for important intellectual content. A.G.T., M.J.S., A.S.-M., J.E.F., and G.D.B. designed the research and made critical revisions of the manuscript for important intellectual content. T.M. made critical revisions of the manuscript for important intellectual content. T.N.A. is the guarantor of this work and, as such, had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.