Intended for healthcare professionals

Letters Saturated fat is not the major issue

Evidence favours an association between saturated fat intake and coronary heart disease

BMJ 2013; 347 doi: https://doi.org/10.1136/bmj.f6851 (Published 19 November 2013) Cite this as: BMJ 2013;347:f6851
  1. Jim Mann, professor1,
  2. Rachael McLean, senior lecturer2,
  3. Lisa Te Morenga, research fellow3
  1. 1Departments of Human Nutrition and Medicine, and Edgar National Centre for Diabetes and Obesity Research, University of Otago, Dunedin 9054, New Zealand
  2. 2Departments of Human Nutrition and Preventive and Social Medicine, University of Otago, Dunedin 9054, New Zealand
  3. 3Department of Human Nutrition, and Riddet Institute, University of Otago, Dunedin 9054, New Zealand
  1. jim.mann{at}otago.ac.nz

Malhotra provides useful reminders about the causes of coronary heart disease (CHD),1 which are complex, with no single factor being “the major issue.”1 Many patients who now present with myocardial infarction are overweight and have features of the metabolic syndrome.

However, contrary to Malhotra’s statement that “advice [to reduce saturated fat intake] has, paradoxically, increased our cardiovascular risks,”1 the past several decades have seen substantial reductions in mortality from CHD.2 Such reductions have occurred in parallel with reductions in saturated fat intake and serum cholesterol concentrations in much of the Western world.3 These observations are supported by findings of cohort studies and clinical trials.4

A meta-analysis of observational studies in nearly 900 000 adults in Western countries showed a linear association between total cholesterol and CHD mortality.4 A similar association has repeatedly been shown for cholesterol and non-fatal CHD.5 Clinical trials of cholesterol lowering by diet or drugs confirm that CHD risk reduction is proportional to the extent of cholesterol lowering.6

Direct evidence for an association between saturated fat intake and CHD is less clear; this is not surprising because cohort studies can be confounded by problems such as not accounting for sources of replacement energy and misreporting of dietary intakes. Nevertheless, a data pooling study of 11 prospective cohort studies showed that replacing saturated fat with polyunsaturated fat significantly reduced CHD risk, whereas substitution with carbohydrate modestly increased the risk.7 Arguably, the strongest confirmation of association comes from randomised controlled trials. A meta-analysis of eight relatively long term trials showed a significant reduction in CHD events in studies where saturated fats were reduced mainly by substitution with polyunsaturated fat.8

Notes

Cite this as: BMJ 2013;347:f6851

Footnotes

References

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