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Associations of fat and carbohydrate intake with cardiovascular disease and mortality: prospective cohort study of UK Biobank participants

BMJ 2020; 368 doi: https://doi.org/10.1136/bmj.m688 (Published 18 March 2020) Cite this as: BMJ 2020;368:m688

Rapid Response:

Scope for Precision Public Health Approaches in De(re)vising Dietary Guidelines for Cardiovascular Health

Dear Editor,

We read with interest the article titled “Associations of fat and carbohydrate intake with cardiovascular disease and mortality: prospective cohort study of UK Biobank participants”. We felt the study raises a number of important points but wanted to draw attention to three points in particular which we feel warrant clarity given current state of practice and understanding.

Firstly, we discovered an error which we would like to bring to the editorial team's attention. In supplemental tables S2 and S3, the authors report that 37.6% of participants were underweight, 0.5% normal weight, 41.8% overweight and 20.2% obese. Based on our knowledge of the UK Biobank participants we suspect that the underweight and normal weight categories have been accidentally reversed. We can only assume that this is an typographical error rather than a more serious error affecting the analysis. However, the “physical measurements” section of supplementary table 2 and 3 warrants checking and correcting.

Secondly, we feel that this study unintentionally conflates an individualised/personalised model with a public health model. A central conclusion is that "dietary advice should be based on current intake". If public health advice is predicated on the analysis of current exact levels of dietary exposure for each and every individual in a population this would cease to be a public health measure. Furthermore, we feel that the author’s statement that "the implications of dietary changes are likely to vary according to the individual’s current diet and therefore, when possible, dietary advice should be personalised" has the potential to be interpreted as a somewhat limited and dated concept of personalised nutrition based on the “one size fits all” approach (1). This envisages personalised nutrition advice as based solely on consideration of current intake while maintaining the assumption that “optimum” macronutrient intake is the same across all individuals regardless of genetics, age, gender and metabolic, immune, inflammatory and disease status. Perhaps the authors are advocating a precision public health approach allowing more targeted population recommendations or interventions (2).

Finally, the study raises concerns with regards to current dietary advice to reduce cardiovascular disease (CVD) risk. As the authors of the current study report, "Intakes of starch and saturated fatty acid (SFA) were not associated with CVD" (for SFA: overall p=0.1, non-linear p=0.06). Thus, this study contributes to a large body of evidence from other observational studies that SFA intake is not associated with CVD (3-7). Furthermore, this study also found that "Replacing SFA with PUFA was not significantly associated with mortality risk but was associated with a higher risk of CVD" (for CVD: overall p<0.001, non-linear p=0.09). This is particularly concerning given that current dietary advice for prevention of CVD favours replacement of SFA with polyunsaturated fatty acids (PUFAs) (8). These findings further support the notion that UK dietary guidelines around cardiovascular health may be inadequate for the whole population and should be reconsidered.

References
1. Dib MJ, Elliott R, Ahmadi KR (2019) A critical evaluation of results from genome-wide association studies of micronutrient status and their utility in the practice of precision nutrition. Br J Nutr. 122(2):121-130.
2. Khoury J M. Precision Public Health: What Is It? [Internet] Centers for Disease Control and Prevention. [updated 2018 May 15] Available from: https://blogs.cdc.gov/genomics/2018/05/15/precision-public-health-2/
3. Chowdhury R, Warnakula S, Kunutsor S, Crowe F, Ward HA, Johnson L, et al (2014) Association of dietary, circulating, and supplement fatty acids with coronary risk: A systematic review and meta-analysis. Annals of Internal Medicine. 160(6):398-406.
4. de Souza RJ, Mente A, Maroleanu A, Cozma AI, Ha V, Kishibe T, et al (2015) Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: Systematic review and meta-analysis of observational studies. BMJ (Online). 351.
5. Harcombe Z, Baker J & Davies B (2017) Evidence from prospective cohort studies does not support current dietary fat guidelines: a systematic review and meta-analysis. Br J Sports Med. 51:1743-1749.
6. Siri-Tarino PW, Sun Q, Hu FB & Krauss RM (2010) Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. American Journal of Clinical Nutrition. 91(3):535-546.
7. Skeaff CM & Miller J (2009) Dietary fat and coronary heart disease: Summary of evidence from prospective cohort and randomised controlled trials. Annals of Nutrition and Metabolism. 55(1-3):173-201.
8. British Heart Foundation. Healthy Eating [internet]. Available from: https://www.bhf.org.uk/informationsupport/support/healthy-living/healthy...

Competing interests: No competing interests

10 April 2020
Anna P Nicholas
Student
Dr Kourosh R Ahmadi PhD
Department of Nutritional Sciences, Stag Hill, University Campus, Guildford GU2 7XH