Here in the UK we look to the Government’s Food Standards Agency (FSA) to guide us regarding what we should be eating, and we also trust them when it comes to ensuring the food industry doesn’t offer us too much shite to eat. Or that’s the theory, anyway. In reality, I reckon the FSA does a pretty poor job on both these counts.
Just look here and here and here for examples.
Anyway, this week I learn that the FSA’s latest thrust to is to persuade us (again) of the perils of saturated fat. You can see what the FSA statement on this here.
Apparently, the FSA is aiming to ensure that saturated fat does not contribute more than 11 per cent of the calories we consume. This, we are told could prevent up to 3,500 deaths a year.
According to Rosemary Hignett, Head of Nutrition at the FSA: ‘Reducing our intakes of saturated fat is a major challenge but would have clear important health benefits.’ But is this really true? Does the science support saturated fat’s killer image, and does eating less of it really save lives?
Probably the most oft-quoted ‘fact’ about saturated fat is that it increases our risk of heart disease. This nutritional nugget is based on two main lines of ‘evidence’:
1. higher saturated fat intakes are associated with an increased risk of heart disease
2. eating saturated fat raised blood levels of cholesterol (and this, we are told, enhances or risk of heart disease)
Let’s examine these in turn.
Over the last 50-odd years, there have been more than two-dozen studies that have analysed the relationship between saturated fat and risk of heart disease [1-26]. All but four of these studies [9,11,19,25] found no association between saturated fat intake and heart disease. And in one study, higher intakes of saturated fat in the diet were found to be associated with reduced narrowing of the arteries supplying blood to the head (the carotid arteries) over time [27].
The largest analysis to date of the relationship between lifestyle factors and risk of heart attack was published in the Lancet medical journal in 2004 [28]. This study analysed a range of risk factors and heart attack risk in some 12,000 heart attack victims and 14,000 healthy individuals from 52 countries around the World. The researchers involved in this study identified several factors, including smoking, high blood pressure, diabetes, a low intake of fruits and vegetables, and low levels of physical activity that appeared to account for 90 and 94 per cent of heart attacks in men and women respectively. Curiously, this review makes no mention of animal fat, or even dietary fat in general, as being an important risk factor for heart attack.
Taken as a whole, the scientific evidence simply does not support the notion that saturated fat is bad for the heart.
From a scientific standpoint, these studies ” referred to as epidemiological studies ” can only at best find associations between things. A better way to test the concept that eating saturated fat causes heart disease is to get people to eat less saturated fat to see if this reduces their heart disease risk over time.
Ideally, studies of this nature should be double-blind, which means that neither the individuals in the study nor the researchers will know whether they are receiving the true intervention or not. These sorts of studies, known as ‘double-blind’ studies, are generally regarded as the gold standard of intervention studies. To date, only two such studies have been performed with regard to heart disease risk or death [37, 44], and neither showed any benefit.
There are some 20 other studies [29-36,38-43,45-50], of which just six [40,42,50,52,58,60] found benefit. So, of a total of 22 studies, 16 found no benefit from cutting back on saturated fat with heart disease risk.
This doesn’t seem like particularly convincing evidence of the supposed benefits of eating less saturated fat. And the evidence looks even less convincing when you consider that the studies that did find benefit are often what is known a ‘multiple intervention’ studies ” which in this case means that in addition to reducing saturated fat, the participants in these studies were subjected to at least one other modification. For example, in one study [29] individuals were given nutritional supplements. In two of the studies [47,49], individuals were asked to emphasise heart-healthy omega-3 fats as well as fruit and vegetables in the diet. The obvious question that multiple intervention studies raise is whether lowered saturated fat in the diet, or the other interventions, or a combination of these things, that proved effective. Because of these limitations, multiple intervention studies cannot be used to judge the effects of reducing saturated fat in the diet.
One way researchers can get a good idea of the overall effect of some treatment or approach is to perform what is known as a ‘meta-analysis’. Here, results from a number of similar studies are grouped together. The largest meta-analysis to examine the effect of modifying fat in the diet was conducted by UK-based researchers and was published in the British Medical Journal [51]. This particular review amassed the data of 27 individual studies. Neither deaths due to cardiovascular disease (such as heart attack and stroke) nor overall risk of death was found to be reduced by makes changes to intake of dietary fat. The results of this review support the notion that eating less saturated fat has little, if any, benefits for our heart and general health.
Never mind this overwhelming lack of evidence for the ‘benefits’ of eating less saturated fat, though, because this won’t stop some doctors and scientists from playing the cholesterol card (see notion 2 above): saturated fat raises cholesterol which we know is bad for the heart. So, eating less saturated fat will reduce cholesterol levels which has to be good for the heart, right?
As with saturated fat, if we really want to make a judgment of the true impact cholesterol has on health, we need intervention studies ” studies in which cholesterol levels are lowered and the effect of this assessed. In 2005 a meta-analysis of 17 studies in which subjects made dietary changes explicitly to reduce blood cholesterol levels was published in the Archives of Internal Medicine [52]. Overall, these studies brought about a 10 per cent lowering of cholesterol levels. Despite this, the amassed results showed no reduced risk of death, neither in healthy individuals, nor even in high-risk individuals who had a history of heart attack or stroke. Basically, taking dietary steps to reduce cholesterol levels (say by reducing saturated fat intake) has not been proven to save lives.
Some, no doubt, will clutch at straws and tell us that eating less saturated fat will reduce risk of other killers conditions such as cancer. Such individuals may be unaware of the results of the Women’s Health Initiative Study, in which outcomes for women put on a ‘healthy’ diet were compared with those on an ‘eat what you like’ diet over 7 ½ years. In this study, the ‘healthy’ eating women consumed 23 per cent less saturated fat than their ‘eat what you like’ counterparts (that’s actually a much bigger reduction in saturated fat intake than the FSA is heading us towards). And at the end of the analyses they found that the ‘healthy’ eating women did not enjoy a reduced risk in any one or more than 20 types of cancer [53-55].
Put this all together and it appears, to me at least, that the idea that cutting back on saturated fat will saves lives is not supported by the science. But then again, it wouldn’t be the first time that we’ve been given official dietary recommendations for which there is no good evidence.
References:
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Thank you for this very excellent compilation of the relevant research.
The evidence that saturated fat is good for you, rather than bad, was very graphically displayed by Doctors Chris and Xand van Tulleken on Tuesday evening in their Channel 4 programme, Medicine Men Go Wild.
For those who didn’t see it, the identical twin doctors lived with the inhabitants of Chukotka, at the farthest northeast region of Russia, on the Bering Sea.
While there, for ten days the twins followed different diets – Chris that of the natives [almost entirely of sea mammals, with a bit of reindeer for variety], while Xand ate a diet of imported Russian processed foods.
At the end of the experiment, Chris’s overall cholesterol had fallen, and Xand’s risen. Not only that, but the ratios between HDL and LDL had improved by 30% for Chris, and deteriorated by 30% for Xand.
Given that these men have identical physiological make-ups, no better demonstration of the benefits of saturated fat and low- or even no- carbohydrate diets could be given.
It should be compulsory viewing for all nutrition students and practitioners until they realise they have been conned by big business.
Thanks for the very useful list of references, Dr Briffa. 🙂
I suppose that reducing sat fat means eating more supposed unsat fat such as vegetable oil. Vegetable oil (other than olive) plus sugar and refined carbs is the main cause of heart disease. The government has realised the importance of not eating hydrogenated oils but all oils are just as bad. This is the biggest change in our eating habits this cebtury or perhaps ever.
Agree that we need to look at how research was done and need proper blind research.
Thanks for that and I think I understand what you are attempting to achieve, however, could you explain how you see the relationship, if any, of saturated fat and inflammation? I see the inuits doing a reasonably good job of health except for their calcium deficiencies but they eat a lot of omega 3’s which means there is less competition at the cell membrane? Are we doing more harm than good telling folk who find change difficult that its not the fat but the amount that they consume combined with other foodstuffs which put strain on the body. Do you find that people only see what they want to see?
The problem is that it is not just the FSA that spews out this garbage about what constitutes a healthy diet! All the programmes and articles in the media propogate the same things … low fat especially saturated fat and lots of carbs in the form of bread, rice and pasta! Of course, I wouldn’t dream of suspecting the motives of the food and pharmaceutical industries in all of this …??!!
Leigh The production of pro and anti inflammatory prostaglandins is related to the type of fat eaten. Anti -inflamm prostaglandins are made with omega 3 fats. Hilda
Wow, this really wasn’t expected, considering how much the nhs and doctors, the FSA etc are always talking about people needing to cut down on their saturated fat… thanks for all the information!
Dr. Briffa,
Thanks for the summary. It’s really hard to believe that saturated fat is unhealthy when we’ve been eating it since the beginning of time! It’s also completely at odds with data from healthy non-industrial cultures like the Inuit and the Maasai. I post info on those types of cultures on my blog from time to time. The formula is pretty simple in my mind: eat the things that healthy cultures have been eating for millenia!
i do not find this info helpful for my school project
the guidelines to healthy eating are simple y do people find it hard to follow them????
Ashley,
The guidelines on healthy eating are WRONG!
ashley,
Good luck with your school project. Come back and let us know how you get on.
Even for those of us who left school thirty years ago the world can be a confusing place.
For your project try to recognise what constitutes ‘mainstream’ knowledge as defined by your syllabus.
Humans began to accumulate knowledge by swapping stories around a campfire tens of thousands of years ago. In with the truth was much myth and legend.
In the 21st century the accumulation of human knowledge has increased beyond recognition. Science and understanding has advanced – BUT – that does not mean us humans know it all. There is still a lot to learn. Even now ‘mainstream’ still includes some myth and legend. People here are looking a little deeper.
Recently, I helped my Yr 8 son research a project on The Gr8 Barrier Reef. He was rewarded with a good grade but I was surprised at the complexity of the topic as set for a 12yo. The reef is a sensitive indicator of climate change. I was reminded, “your never too old to learn”
Leigh,
in relation to the Inuits I offer 1, http://tundramedicinedreams.blogspot.com/2007/01/yupik-eskimo-diet-and-obesity.html AND 2, http://discovermagazine.com/2004/oct/inuit-paradox.
At first, Johansson didn’t quite see the merit in the ethnic diet while years later there would appear to be no merit in the Developed Western Diet for the Inuit.
At least Johansson lived in an age where the pursuit of understanding counted for something.
Well Dr. Briffa,
Thanks for your book and your enlightening dissemination of the rubbish the Government want to stuff down our metaphorical throats.
Now the only person I must convince is my wife. She just insists, I need exercise. Yes I could do more, if my arthritis would let me. Instead though, she just rolls her eyes and says.. ‘Another fad diet you want to go on!’S
I can’t win!
regards
JW