Author’s reply to Lichtenstein, Tedstone and Pyne, Mann and colleagues, Lim, and CliftonBMJ 2013; 347 doi: https://doi.org/10.1136/bmj.f6855 (Published 19 November 2013) Cite this as: BMJ 2013;347:f6855
- Aseem Malhotra, interventional cardiology specialist registrar1
Saturated fat is known to increase low density lipoprotein (LDL)-cholesterol. However, unlike carbohydrates, saturated fat also raises high density lipoprotein (HDL)-cholesterol and reduces triglycerides, with little effect on total cholesterol:HDL ratio—thought to be a better predictor of coronary heart disease (CHD) events than total cholesterol alone.1 2
The food source of saturated fat may be more important. A recent multi-ethnic study found that high intake of dairy saturated fat was associated with a lower CVD risk but high meat intake was associated with increased risk.3 Although evidence supports replacing saturated fat with polyunsaturated fat to reduce CHD events,4 5 6 this benefit may be specific to omega 3, with omega 6 polyunsaturated fatty acids in vegetable oils implicated in raising proinflammatory atherogenic LDL. This may be why a reanalysis of unpublished data found that cardiac patients who replaced butter with safflower oil and margarine containing omega 6 had increased all cause and cardiovascular mortality despite a 13% reduction in total cholesterol.7
Furthermore, the food industry’s exploitation of the “low fat” mantra has resulted in diets high in refined carbohydrate.8 It has fuelled worsening obesity and atherogenic dyslipidaemia, a metabolic state defined by increased triglycerides, reduced HDL-cholesterol, and increased proportions of small dense LDL particles. A reduction in carbohydrate intake but not saturated fat seems to improve this dyslipidaemic profile.7 The food industry has also exploited the obsession with total energy consumed rather than nutritional value by adding sugar to many processed foods. A nine teaspoon sugared cola has under 150 calories but the EPIC study found that drinking one can a day increased the risk of type 2 diabetes independently of body mass index. Conversely, in the PREDIMED study, consumption of four tablespoons of extra virgin olive oil a day (500 calories) significantly reduced risk of heart attack and stroke.
After a two year review of 16 000 studies, Sweden is the first Western nation to reject the “low fat” dietary dogma—advocating a diet that is high fat and low in refined carbohydrates as the best for cholesterol profile and weight loss. Promoting a Mediterranean diet would reduce the intake of processed food and added sugar, which unlike fat and protein has no nutritional value, causes dental caries, and is driving the metabolic syndrome.9 Such a policy might offer the best dietary solution to improving public health.
Cite this as: BMJ 2013;347:f6855
Competing interests: None declared.
Full response at www.bmj.com/content/347/bmj.f6340/rr/671980.