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Analysis Science and Politics of Nutrition

Dietary fat and cardiometabolic health: evidence, controversies, and consensus for guidance

BMJ 2018; 361 doi: https://doi.org/10.1136/bmj.k2139 (Published 13 June 2018) Cite this as: BMJ 2018;361:k2139

Food for thought

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Could we agree to demonize processed food, not saturated fat?

"Animal fats, for instance, are the main sources of saturated fats in many modern diets, but some animal fats are higher in monounsaturated fats than saturated fats, and polyunsaturated fats in vegetable oils will typically contain both omega 3 and omega 6 fatty acids in different concentrations."

Much of the demonization of saturated fat derives from a misunderstanding of what saturated fat actually is. A clarity of understanding and terminology could facilitate agreement. The extract from the paper quoted above contains a number of such examples:

1) Animal fats are not the main sources of saturated fats in the US or the UK.
Processed food is the main source of saturated fat in modern diets. The Dietary Guidelines for Americans documented the sources of saturated fat in the American diet (fig. 3-4, p.26).1 Pizza, desserts, candy, potato chips, pasta, tortillas, burritos and tacos accounted for 32.6% of saturated fat consumed in the diets of US citizens aged 2 years and older. 9.3% of dietary saturated fat came from sausages, frankfurters, bacon, ribs and burgers. 12.8% came from chicken and mixed chicken dishes, beef and mixed beef dishes, and eggs and mixed egg dishes. A further 24.5% was unaccounted for and collated as “All other food categories”; likely including, if not predominantly being, processed foods. The natural foods listed were cheese, milk, butter, nuts and seeds, which collectively accounted for 20.8% of saturated fat intake. It would have been ideal for unprocessed chicken, beef and eggs to have been separated from processed meals containing these ingredients. The diagram presented in the Dietary Guidelines is clear nonetheless. Processed foods account for the majority of saturated fat intake in the diets of Americans.

The UK classification is similar. The Family Food Survey (table 2.4, p.18) documented sources of saturated fat in the UK diet.2 Bread, cakes, buns, pastries, biscuits, cereals, confectionery and other processed foods accounted for 33% of saturated fat intake. Milk, cream and cheese accounted for 24% of dietary saturated fat. However, much of this was processed food as it included instant milks, sweetened yoghurts and milk desserts. Processed meat accounted for 16% of saturated fat intake, while unprocessed (carcass) meat was 5%, fish 1% and eggs 1% of saturated fat intake. Fats and oils made up the remaining 19%, the vast majority of these being vegetable oils. As with the US, processed food accounted for the majority of the saturated fat intake of the UK.

2) The statement – “some animal fats are higher in monounsaturated fats than saturated fats” – would be more accurately stated as “all foods of animal origin, with the exception of dairy products, have more unsaturated than saturated fat.” Meat, fish, eggs and even lard have more unsaturated than saturated fat. A typical steak is 71% water, 21% protein, 5% unsaturated fat and 2% saturated.3 Saturated fat is literally the last thing that a steak is. Gram for gram, olive oil has seven times the saturated fat of the steak.4

3) It is not just polyunsaturated fats in vegetables oils that contain essential fatty acids. Every food that contains fat – from butter to blueberries (yes – a trace!) – contains all three fats: saturated; monounsaturated and polyunsaturated. Every food that contains fat thus also contains essential fatty acids.

This paper was one of a selection from the BMJ/Swiss Re “Food for thought” initiative. The papers and accompanying conference were unique in their forced collaboration of disparate views. There is opportunity for agreement among health professionals. If the public health message were revised to advise citizens to eat natural food and not processed food, saturated fat intake would fall accordingly although the health benefit would likely be the concomitant reduction in sucrose, trans fats, refined carbohydrates and other processed ingredients deleterious to human health. Human beings evolved to eat foods available from the natural environment.5 It does not seem logical to advise populations away from carcass meat, dairy produce, eggs, nuts and seeds, in the name of saturated fat, when the modern processed foods, biscuits, cakes, pizza, desserts and ready meals, are more sensibly related to modern illness.6

It seems simple and obvious to suggest that populations should return to eating the natural, unprocessed, food that was consumed before obesity and diabetes reached epidemic proportions; yet this is considered heresy by public health advisors. Clarification of the distinction between processed food and saturated fat could provide opportunity for agreement that processed food is unhealthy, while saturated fat is a natural part of most natural foods. Given that every food that contains fat, contains all three fats, the notion that saturated fat is harmful and unsaturated fat is healthful is illogical given their co-existence in foods required for human survival.

References
1. Department of Health and Human Services (HHS). Dietary Guidelines for Americans. In: Department of Health and Human Services (HHS), ed., 2010.
2. A National Statistics Publication. The Family Food Survey. In: DEFRA, ed.: The Department for Environment, Food and Rural Affairs, 2010.
3. United States Department of Agriculture ARS. Beef, bottom sirloin, tri-tip, separable lean only, trimmed to 0" fat, choice, raw [URMIS #2244], 2013.
4. United States Department of Agriculture ARS. Oil, olive, salad or cooking, 2013.
5. Gowlett JAJ. What Actually was the Stone Age Diet? Journal of Nutritional and Environmental Medicine 2003;13(3):143-47. doi: 10.1080/13590840310001619338
6. Harcombe Z, Baker J, Davies B. Food for Thought: Have We Been Giving the Wrong Dietary Advice? Food and Nutrition Sciences 2013;4(3):240-44. doi: 10.4236/fns.2013.43032

Competing interests: I write and publish content in the field of diet and health.

26 June 2018
Zoe Harcombe
Independent researcher
Independent
Wales