Saturated fat, cholesterol and controversy – the sat fat spat!
Every few months the headlines say ‘butter is back’, ‘saturated fat is good for you’ or ‘calorie counting is over’. Then all too often, the study in question is challenged or discredited, but the damage is done…
In March 2014, national headlines declared “Saturated fat 'ISN'T bad for your heart'” (Hope, 2014) suggesting it is perfectly safe to gorge on butter, cheese and sausages. The study, published in the Annals of Internal Medicine pooled the results of 72 selected studies looking at the link between fat and heart disease and suggested that saturated fat may not lead to heart disease after all (Chowdhury et al., 2014). However, the analysis of two of the six studies of omega-6 fats was incorrect – they got the numbers wrong. Results from other relevant studies were not included. They did not mention a review of prospective studies in which a significant reduction in the risk of heart disease was found in relation to polyunsaturated fat. In this analysis, switching from saturated to polyunsaturated fat lowered the risk of heart disease – that was not discussed. They also failed to point out that most of the monounsaturated fat in the studies they looked at was from red meat and dairy sources; so their findings would not necessarily apply to fats from nuts, olive oil and other plant sources. Therefore their conclusions regarding the type of fat being unimportant were wrong. Professor Walter Willett, chair of the Department of Nutrition at Harvard School of Public Health (the Heisenberg of Nutrition!) said: “…this meta-analysis contains multiple serious errors and omissions, the study conclusions are misleading and should be disregarded” (Willett et al., 2014). Two months later a correction was published pointing out the errors in this study (Chowdhury et al., 2014a).
In February 2015, the online journal Open Heart published a study suggesting UK dietary guidelines were based on shaky evidence (Harcombe et al., 2015). The authors of the study said that they didn’t know what evidence was available when the guidelines were written so they just selected six randomised control studies (RCTs) published before 1983 – all were conducted in men, most of whom already had heart disease. Their results suggested that advice to control saturated fat intake did not affect deaths from heart disease among this small number of unwell men. But that doesn’t mean the recommendations are wrong…
Headlines declared “Butter ISN'T bad for you after all” (Hope, 2015). However, the study was slammed by experts; Victoria Taylor at the British Heart Foundation said: “guidance in the UK is based on a consensus of the evidence available” (British Heart Foundation, 2015) and
Professor Christine Williams, Professor of Human Nutrition at the University of Reading, said: “The claim that guidelines on dietary fat introduced in the 1970s and 80s were not based on good scientific evidence is misguided and potentially dangerous” (Tran, 2015).
The concept of this study was scientifically flawed. Why they chose to look at old studies retrospectively is unclear – surely the guidelines we have now would be better-challenged if the current research presented a different picture? It doesn’t, there is a substantial body of current evidence supporting the case that saturated fat is bad for health. Even the accompanying Open Heart editorial questioned the validity of the study; cardiologist Rahul Bahl, of the Royal Berkshire NHS Foundation Trust, wrote: “Public policies generally do not require RCT evidence, so to advocate their withdrawal here on the basis of the absence of such evidence seems unusual”.
It turns out, the lead author, pro-fat campaigner Zoe Harcombe, runs a diet-club and has published books on her version of good nutrition. Harcombe advised people to ‘ignore public health advice’ in a presentation she wrote for the Weston A Price Foundation, a fringe US organisation which claims to be dedicated to promoting good nutrition by restoring nutrient dense animal products to the diet (Harcombe, 2011). They receive substantial financial support from the animal farming industry and claim that saturated animal fat is essential for good health and that animal fat intake and high cholesterol levels have no link with heart disease. This contradicts what all leading health advisory bodies in the world say.
A month after the publication of the Open Heart study, Pascal Meier, Editor-in-Chief of Open Heart, issued the following statement: “Following comments from readers, and post-publication discussions within our editorial team, the authors of this paper were asked to update their competing interest statement. The potential competing interests relate to one of the authors of the article, Mrs Harcombe, who has previously published books on diet and nutrition, and is also a co-director of a company that gives dietary advice (The Harcombe Diet Co.) and co-director of a publishing company (Columbus Publishing) that publishes books on diet and nutrition”.
Meier said “In this case, Open Heart feels that the books and companies with which Mrs Harcombe has been involved should have been declared. From our point of view, a competing interest exists when professional judgement concerning a primary interest (such as validity of research) could potentially be influenced by a secondary interest (such as financial gain)” (Harcombe et al., 2015a).
In September 2015, US dietary guidelines were targeted in a similar way in a study in the British Medical Journal which questioned the link between saturated fat and heart disease (Teicholz, 2015). The author was journalist Nina Teicholz, who also wrote a book called The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet. In an open letter to the British Medical Journal, Dr David Katz of Yale University School of Medicine expressed his concern at them publishing a journalist’s commentary as if it were authoritative. Katz said “It is, in a word, absurd and testimony to the breakdown in integrity where science and media come together” (Katz, 2015).
Errors in the study were identified and the next month the following correction was published: “This Feature by Nina Teicholz stated that when the guidelines advisory committee started its work in 2012 there had been several prominent papers, including a meta-analysis and two major reviews (one systematic), that failed to confirm an association between saturated fats and heart disease. This statement did not aptly reflect the findings of the more authoritative of these reviews, by Hooper et al., which found that saturated fats had an effect on cardiovascular events but failed to confirm an effect on cardiovascular mortality” (Teicholz, 2015a).
There is a substantial body of evidence supporting the case that saturated fat is bad for health. The study by Hooper et al. referred to in the British Medical Journal’s correction is a Cochrane Review. These are systematic reviews of primary research in human healthcare and health policy; they are internationally recognised as the highest standard in evidence-based healthcare – often referred to as the gold standard. Hooper’s review analysed 48 studies including over 65,000 participants. It was found that reducing saturated fat (but not total fat) intake reduced the risk of heart attack and stroke by 14 per cent (Hooper et al., 2012). That was just by reducing saturated fat – not cutting out meat and dairy. The results could have been even more impressive if that had happened!
In May 2016, the National Obesity Forum (NOF) published a report saying that avoiding butter, cream and cheese is actually fueling obesity epidemic and that official advice on low-fat diets and cholesterol is wrong (National Obesity Forum, 2015). National headlines declared that: “Official advice on low-fat diet and cholesterol is wrong” (Guardian, 2015). Dr Aseem Malhotra, one of the authors of the report, described Public Health England’s new Eatwell Guide as a metabolic timebomb! He says: “We must urgently change the message to the public to reverse obesity and Type 2 diabetes. Eat fat to get slim, don’t fear fat; fat is your friend”.
The NOF report describes calorie counting as a red herring, as calories from different foods have different effects on the human body. It emphasises the fact that in spite of dietary guidelines, the number of people with obesity and type 2 diabetes is rising. But this doesn’t prove that the guidelines are wrong; it merely shows that people are ignoring them. Public Health England said “the report is irresponsible and misleads the public” (Public Health England, 2016). Professor Susan Jebb from Oxford University condemned the report as “non-rigorous and irresponsible” (Bodkin, 2016) questioning their motives as they accept funding from the pharmaceutical industry (they are supported by GlaxoSmithKline, Sanofi-Aventis, Roche Products as well as the British Meat Nutrition Education Services and weight loss business LighterLife UK). At the time of writing, four of the seven board members of NOF had resigned, while a fifth was considering his options.
Also at the time of writing, the British Medical Journal published a review questioning the validity of the cholesterol hypothesis in the elderly (Ravnskov et al., 2016). This lead to more sensationalist headlines saying: “High cholesterol 'does not cause heart disease'” (Bodkin, 2016a). You’d think they would tread more carefully after last time. A bit of digging around revealed that four of the authors have written books challenging the idea that cholesterol is bad for you and nine are members of a group called The International Network of Cholesterol Skeptics, who oppose the idea that animal fat and cholesterol play a role in heart disease. Dr David Nunan, a senior research fellow at the Nuffield Department of Primary Care Health Sciences at the University of Oxford, performed a post-publication critical appraisal of this review and said: “Given that the authors failed to account for significant confounding as well as the methodological weaknesses of both the review and its included studies, the results of this review have limited validity and should be interpreted with caution. At this time it would not be responsible, or evidence-based, for policy decisions to be made based on the results of this study” (Nunan, 2016).
The pro-fat and animal farming lobbies have their sights fixed on sugar as the villain of the piece. It may well be that focusing on saturated fat as the primary dietary villain for heart disease has distracted from the risks posed by sugar, but replacing one villain with another is not helpful. Unfortunately the pro-fat crusade will continue because the meat and dairy industry has money and influence. However, it seems the government will not be swayed on this and the scientific community is well-prepared to stand their ground. It’s a shame these few, flawed studies received so much media attention.