Last week I wrote about the Unilever-funded Fat Information Service and the claim on its website that “The evidence shows clearly that the risk of developing heart disease is reduced when saturated fats are replaced with unsaturated fats.” The claim was made by dietician Dr Carrie Ruxton, and to support her claim she referenced a review of dietary studies published in 2011 [1]. The most recent incarnation of the study was published last year. I’ve read them both, and neither appears to contain evidence to support Dr Ruxton’s assertion.
In an email I asked Dr Ruxton to refer specifically to the part of the review which supports he claim, and she provided me with this:
One [sic] page 19 of the 2011 Cochrane review, it is stated that: “dietary saturated fat reduction (through reduction and/or modification of dietary fat) may be protective of cardiovascular events overall, reducing them by 14%”
The implications for practice on page 29 also states that: “Dietary change to reduce saturated fat and partly replace it with unsaturated fats appears to reduce the incidence of cardiovascular events”
However, ‘cardiovascular events’ covers a multitude of conditions and events, not all of which are heart-related (e.g. stroke and circulatory problems in the legs known as ‘peripheral vascular disease’). To not understand the difference between ‘heart disease’ and ‘cardiovascular events’ either shows a fundamental lack of understanding or intellectual dishonesty (as I suggest to Dr Ruxton in an email to her which I reproduce in full below). There were also things about the ‘positive’ evidence which casts considerable doubt on whether any change in dietary fat was responsible for whatever benefits were seen (see below).
I also point out this critical fact: when the reviewers looked at heart-disease related outcomes (heart attack), there was no reduced risk associated with lower-fat or modified fat diets.
All these findings are the same across both 2011 and 2012 versions of the review.
Here’s my email response in full:
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Hi Carrie
Thanks for your response.
The most recent incarnation of this review was published in 2012 (though it is, essentially, the same review as the one you refer to).
With regard to the 14 per reduction in ‘cardiovascular events’, this is a composite endpoint which included not just heart disease-related outcomes (remember, your claim was about heart disease), but also cardiovascular deaths (not all will be cardiac in nature) and cardiovascular morbidity (which may also include non-cardiac events such as stroke and peripheral vascular events).
In other words, you cannot use this evidence to support your claim, as the outcomes were not confined to ‘heart disease’. It is almost inconceivable to me that you either do not understand the difference between ‘heart disease’ and the composite outcome used in the review, or are attempting to pass them off as the same thing. Your response demonstrates either a failure to properly interpret the findings of this review or intellectual dishonesty.
Plus, statistical significance disappeared once systematic differences in care or non-fat-related differences in care were controlled for. In other words, there is considerable doubt whether fat reduction or modification had any benefits at all.
The review did look specifically at the impact of either lower-fat diets or fat-modified diets on risk of myocardial infarction (which is obviously of direct relevance to your claim). Here’s the summary of this evidence as it appears in the review:
There was no clear effect of altering dietary fat intakes (compared to usual diet) on myocardial infarction (RR 0.93, 95% CI 0.84 to 1.02, I2 6%, 64,891 participants, 2068 people with fatal or non-fatal myocardial infarcts, peffect 0.13) ( Analysis 2.1). Neither was there any effect of any of the distinct dietary fat changes: modified fat intake RR 0.91 (95% CI 0.72 to 1.16, I2 45%, 11,831 participants, 579 people with at least one myocardial infarct, peffect 0.46); reduced fat vs usual fat intake RR 0.97 (95% CI 0.86 to 1.08, I2 0%, 50,522 participants, 1203 people having a myocardial infarct, peffect 0.54); and reduced and modified fat vs usual intake RR 0.90 (95% CI 0.72 to 1.11, I2 0%, 2538 participants, 286 people with myocardial infarcts, peffect 0.32).
In summary, no statistically significant effects were found on risk of heart attack.
There was nothing at all in the review that supports your claim that: “The evidence shows clearly that the risk of developing heart disease is reduced when saturated fats are replaced with unsaturated fats.”
Would you please respond?
Kind regards
John Briffa
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In her response to me, Dr Ruxton accused me of being “rather pedantic.”
Really?! Is it pedantic to point out that the claim she made was in no way at all supported by the review she cites? Is it ‘pedantic’ to point out the evidence which specifically contradicts her claim?
But, Dr Ruxton explains all when she tells me that:
While the Cochrane review used the terminology of ‘cardiovascular events’, the consumer tends to understand ‘heart disease’ better and this is why I chose this term for my press quote.
But as we know and as Dr Ruxton should know, ‘cardioavascular events’ and ‘heart disease’ are not the same thing at all.
And Dr Ruxton has nothing to say at all on the fact that when impact on risk of heart attack was assessed, no benefits were found at all.
Dr Ruxton also tells me that:
The view that reducing saturated fats and replacing them with unsaturated fats lowers heart disease risk is not at all controversial and is supported by public health bodies including NHS Choices…
and supplied this link http://www.nhs.uk/Livewell/Goodfood/Pages/Fat.aspx and this extract:
[box style=”rounded” border=”full”]“We all need some fat in our diet. But too much of a particular kind of fat – saturated fat – can raise our cholesterol, which increases the risk of heart disease. It’s important to cut down on fat and choose foods that contain unsaturated fat.
Eating a diet high in saturated fat can cause the level of cholesterol in your blood to build up over time. Raised cholesterol increases your risk of heart disease. Foods high in saturated fat include …butter
Eating unsaturated fats instead of saturated can help lower blood cholesterol. Unsaturated fat … is found in … sunflower and olive oils”.[/box]
Notice that nowhere in these extracts is the claim made that replacing saturated fat with a ‘healthier’ fat reduces the risk of heart disease. And quite right too, seeing as there is essentially no evidence to support that idea.
In her response to the original piece, Dr Ruxton tells us that:
I can see that John and many of those who have commented on this forum do not believe the evidence suggesting that saturated fats represent a risk to cardiovascular health. You are, of course, entitled to your opinion, as am I.
Actually, I am not sure any of us are entitled to our opinions, when we have abundant evidence to look to. We know that reducing saturated fat or replacing it with other fats does not reduce the risk of heart attack, stroke, risk of death from cardiovascular disease or overall risk of death (all findings from the review Dr Ruxton herself quotes). And this is what really matters.
In my experience, individuals who do not believe that saturated fat poses hazards for health hold that view because they have read and assimilated the research and found nothing to incriminate saturated fat in terms of its influence on health.
Not only do we have the evidence being discussed here, but we also have several recent reviews of the epidemiological evidence that simply fail to link saturated fat and heart disease [2,3,4].
Anyone can make an honest mistake, of course, but I think Dr Ruxton compounds her error by refusing to accept the facts even when they were put in front of her face.
In her response to the previous post, she describes herself as an ‘independent dietitian’. Personally, I believe that use of the word ‘independent’ here is stretching it a bit, seeing as the Fat Information Service (and, I assume, Dr Ruxton) is bankrolled by Unilever.
To my mind, either Dr Ruxton does not have the ability to interpret the review she cites or has misinterpreted it and misled us. Only she will know the truth. The rest of us will just have to decide for ourselves.
References:
1. Hooper L, et al. (2011). Reduced or modified dietary fat for preventing cardiovascular disease. The Cochrane Library
2. Mente A, et al. A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch Intern Med 2009;169(7):659–69
3. Siri-Tarino, PW, et al. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease, Am J Clin Nutr 2010;91(3):535–46
4. Skeaff CM, et al. Dietary fat and coronary heart disease: summary of evidence from prospective and randomised controlled trials. Annals of Nutrition and Metabolism 2009;55:173–201
UPDATE: As of some time on 24 July 2013 clicking on the link to where Dr Ruxton makes her unsubstantiated claims on the Fat Information Service website returns this page:
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