For years, we’ve believed that saturated fat is bad for the heart. The dogma was that this particular type of fat raises levels of cholesterol levels, promotes atherosclerosis and causes heart disease. But where is the evidence?
It’s pretty thin on the ground as it happens. In fact, more and more studies are emerging that show saturated fat isn’t harmful to heart health as once thought (1). Old villains, such as milk and butter have now been vindicated. My search on Medline reveals that saturated fat isn’t synonymous with heart disease.
Fundamentally, not all saturated fatty acids behave the same in the body. For example, stearic acid (found in meat) and palmitic acid (found in dairy fat) have been shown to have no effect on cholesterol (2). In fact, dairy fat raises only the large (not harmful) LDL particles and therefore does not cause furring of the arteries, as widely believed (3).
Surprisingly, saturated fat from certain foods (e.g. dairy) may even be beneficial. Milk – regardless of fat level – is in fact associated with a lower blood pressure and a reduced risk of heart disease, stroke and type 2 diabetes. This is partly explained by the fact that dairy foods contain protein, calcium and other nutrients that may modulate the effect of saturated fat on health.
Need more reasons to switch to butter and whole milk? A University of Texas study found that people with the highest intakes of dairy fat had the lowest cardiovascular risk (4). And two research reviews by Cardiff University researchers suggest that milk may even protect against heart disease, stroke and type 2 diabetes – the risk was lower in those with the highest consumption of dairy foods (5, 6).
So why have obesity and diabetes rates been rising? One of the problems is that people have been replacing fat with highly processed refined carbohydrates – a recipe for disaster. We now know that such a diet (high-carb low-fat) sends blood triglyceride (fat) levels soaring and makes a heart attack more likely. One UK study found that those following current government guidelines ie a high carb low fat diet, ended up with higher levels of blood fats and lower levels of ‘good’ HDL levels, changes that increased, not decreased, their risk of heart disease (7). Cutting saturated fat and replacing it with carbs is probably the worst thing you can do.
So why has saturated fat been assigned the role of villain for so long? Its wrongful accusation stems from Ancel Keys seven countries study, which showed that countries with the highest saturated fat intake had the highest number of deaths from heart disease. This research has now been discredited – he ignored the data from 15 other countries (including France, Spain and Italy) that didn’t tally with his hypothesis. I was fascinated by John Briffa’s analysis of 2008 data from more than 40 countries that shows the opposite relationship to be true (8, 9)! It turns out that countries with the highest % calories from saturated fat have the lowest rate of death due to heart disease.
The real culprits? Processed fats and sugar. According to a 2011 review published in the American Journal of Clinical Nutrition replacing saturated fat with highly refined carbohydrates results in a higher risk of heart disease (10). Sugar-sweetened drinks, in particular, are to blame for weight-gain, type 2 diabetes and cardiovascular disease, say researchers, writing in the journal Circulation (11).
So what does all this mean in practice, what should you be eating?
• This isn’t a licence to gorge yourself on saturated fats; you still need to keep a check on total calories!
• I’m not advocating a ‘high fat’ or a ‘low carb’ diet either – I’d advise a sensible balance of around 35 – 40% fat, 20 – 25% protein (depending on your exercise programme) and the rest from low or moderate GI carbs
• If you step up your fat intake, cut carbs so you don’t end up over eating calories
• Include foods naturally rich in fats, whether saturated e.g. butter, cheese, milk, eggs, fish, organic meat and coconut oil, or unsaturated e.g. nuts, olive oil, avocado, seeds
• Avoid processed fats, hydrogenated fats, processed meats. Choose butter, not margarine or reduced fat spreads
• Minimise sugar, especially soft drinks, biscuits, confectionery
• Stick to ‘real’ foods; avoid highly processed carbs, and ‘reduced fat’ foods (spreads, cookies, cakes, desserts)
(1) Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr. 2010;91(3):535-546.
(2) Lock AL, Destaillats F, Kraft J, German JB. Introduction to the proceedings of the symposium “Scientific Update on Dairy Fats and Cardiovascular Diseases.” J Am Coll Nutr. 2008;27(6):720S-722S.
(3) German JB, Gibson RG, Krauss RM, et al. A reappraisal of the impact of dairy foods and milk fat on cardiovascular disease risk. Eur J Nutr. 2009;48(4):191-203.
(4) de Oliveira Otto MC, Mozaffarian D, Kromhout D, et al. Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis. Am J Clin Nutr. 2012;96(2):397-404.
(5) Elwood PC, Givens DI, Beswick AD, Fehily AM, Pickering JE, Gallacher J. The survival advantage of milk and dairy consumption: an overview of evidence from cohort studies of vascular diseases, diabetes and cancer. J Am Coll Nutr. 2008;27(6):723S-734S.
(6) Elwood PC, Pickering JE, Givens DI, Gallacher JE. The consumption of milk and dairy foods and the incidence of vascular disease and diabetes: an overview of the evidence. Lipids. 2010;45(10):925-939.
(7) Arefhosseini SR et al Effect of advice to increase carbohydrate and reduce fat intake on dietary profile and plasma lipid concentrations in healthy postmenopausal women. Ann Nutr Metab. 2009;54(2):138-44. Epub 2009 Apr 1.
(9) European cardiovascular disease statistics (2008 edition). British Heart Foundation Health Promotion Research Group Department of Public Health, University of Oxford and Health Economics Research Centre, Department of Public Health, University of Oxford
(10) Astrup A. et al The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010? Am J Clin Nutr. 2011 April; 93(4): 684–688.
(11) Vasanti S. et al Sugar Sweetened Beverages, Obesity, Type 2 Diabetes and Cardiovascular Disease risk. Circulation. 2010 March 23; 121(11): 1356–1364.
(12) Fung TT, Malik V, Rexrode KM, Manson JE, Willett WC, Hu FB. Sweetened beverage consumption and risk of coronary heart disease in women. Am J Clin Nutr. 2009;89:1037–1042.
(13) Jeff S Volek 1 and Cassandra E Forsythe The case for not restricting saturated fat on a low carbohydrate diet Nutr Metab (Lond). 2005; 2: 21.