I had a press release recently alerting me to the presence of the Fat Information Service. On the face of it, this ‘service’ seeks to provide us with balanced and accurate information and advice about the sorts of fat we should be eating in our diets. It claims, among other things, to provide “Access [to] reliable information about the role and benefits of dietary fats and oils, including how to differentiate good fats from bad fats” and help us “Understand the facts from fiction when it comes to dietary fats and oils.”
It is funded by Unilever – manufacturer of a range of margarines and other food products that are, supposedly, good for cardiac health. This does not mean that the advice offered by the Fat Information Service is inherently bad. But it does mean there’s a conflict of interest here which might, somehow, influence the ‘expert’ advice it offers through its hired hands.
In this section of the site Dr Carrie Ruxton (a ‘registered dietitian and public health nutritionist with more than 20 years experience in nutrition and health’) tells us that:
“The evidence shows clearly that the risk of developing heart disease is reduced when saturated fats are replaced with unsaturated fats.7”
The study that is referenced here is this one: Hooper L, et al. (2011). Reduced or modified dietary fat for preventing cardiovascular disease. The Cochrane Library (7).
The most recent incarnation of this review was published in 2012 [1]. I’ve read them both but did not recall seeing any evidence supporting Dr Ruxton’s claim, so went back to check.
This research comes in the form of so-called meta-analyses (amassing together of similar studies) which assessed the effects of:
1. changes in the nature of the fat in the diet (e.g. swapping saturated fat for polyunsaturated fat) – fat ‘modification’
or
2. changes in the amount of fat in the diet (e.g. a low-saturated diet)
or
3. both
on risk of cardiovascular diseases such as heart attack and stoke. Before we get on to some of the negative findings of this study (and there are plenty), let’s focus first of all on the stand-out ‘positive’.
The study, apparently, found that: “reducing saturated fat by reducing and/or modifying dietary fat reduced the risk of cardiovascular events by 14%…”
‘Cardiovascular events’ is an example of a ‘composite endpoint’. Essentially, what this means is the lumping together of lots of different outcomes together. With regard to composite endpoints, the wider we cast our net, the more likely we are to find a result that is ‘statistically significant’. Cardiovascular events’ were, in this research, made up of
“cardiovascular deaths, cardiovascular morbidity (non-fatal myocardial infarction, angina, stroke, heart failure, peripheral vascular events, atrial fibrillation) and unplanned cardiovascular interventions (coronary artery bypass surgery or angioplasty).”
As far as cardiovascular events go, one could not cast one’s net any wider. Oh, and it should perhaps be borne in mind that any benefits seen here were only seen in men (none in women).
The strength of this evidence was described by the authors of the review as ‘moderate’, meaning that:
“further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.”
This sounds circumspect, and for good reason too. That’s partly because many of these studies did not just test the impact of lowering or modifying fat in the diet. Some, for instance, employed other dietary changes (e.g. in some, dietary supplements were given). This can bias results in favour of the ‘active’ (low- or modified-fat group). When these differences were taken into consideration, the reduced risk of ‘cardiovascular events’ disappeared.
Also, in about half the studies assessed, there were differences in the ‘systematic care’ that people received. This is another thing that could bias results in favour of the ‘active group’. Again, when differences in systematic care were factored into the equation, the apparent benefits of low- or modified-fat eating evaporated.
In other words, the results suggest that any benefit seen in terms of cardiovascular event reduction was not due to any change in fat intake per se, but other changes employed in the studies.
The authors performed a statistical strategy known as a ‘funnel plot’ which seeks to determine if there is a likelihood that some evidence exists which has not been published. The authors concluded that: “…it is likely that a few small studies with more cardiovascular events in the intervention groups may be missing from the review.” If this is the case, then this would actually worsen the results seen in the groups eating low- or modified-fat diets.
Getting back to Dr Ruxton’s claim, though, what evidence is there that “risk of developing heart disease is reduced when saturated fats are replaced with unsaturated fats.”? It appears that what Dr Ruxton is referring to here are studies of fat ‘modification’. So, did this review find that fat modification reduced the risk of heart disease?
Err, actually no. The review found that even after long-term modification of fat, there was no reduced risk of heart attack. There was no reduced risk of death due to cardiovascular disease or overall risk of death, either. Precisely the same results were found, by the way, for approaches in which fat reduction (rather than modification) were the order of the day.
In support of her claim that “risk of developing heart disease is reduced when saturated fats are replaced with unsaturated fats” Dr Ruxton cites a study that shows no such thing. I’ve contacted Dr Ruxton and she tells me she’s consulting people internally at the Fat Information Service responsible for doing ‘background research’ and putting text on the website. Let’s see what comes out of this. However, it seems to me that Dr Ruxton has grossly misrepresented the findings of the review.
My feeling is this is not good enough from a person working for an organisation that purports to provide accurate advice about dietary fats. Is the endgame here for us to be better informed about how to eat to improve our health? I honestly doubt it. My sense is the Fat Information Service is a kind of dietary propaganda machine that exists to convince people of the nutritional virtues of margarine over butter. My advice: don’t swallow it.
References:
1. Hooper L, et al. (2012). Reduced or modified dietary fat for preventing cardiovascular disease. The Cochrane Library. Published online 16 May 2012 DOI: 10.1002/14651858.CD002137.pub3 [hr]
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