Friday 2 June 2017

Interview with Frits Muskiet about fat

The American nutritional researcher Ancel Keys pioneered the Fat Avoidance advice that has determined our dietary choices for decades. But according to Frits Muskiet, Professor Emeritus of Pathophysiology and Clinical Chemical Analysis, this has only contributed to our unhealthy eating habits.


“Ancel Keys was instrumental in probably the greatest error in the history of nutritional science” – Frits Muskiet


Ask a random person about the unhealthiest eating habit and it is very likely that you will hear: 'eating fat’. Why is that?


In 1978, Ancel Keys published his Seven Countries Study. As a result of selective publication of results, since 1985 the consumption of saturated fat, cholesterol and 'dietary fat’ has generally been associated with cardiovascular disease. This has resulted in dietary recommendations that saw the population switch ‘en masse’ to a different diet; mainly eggs and saturated fat were avoided and replaced by linoleic acid and carbohydrates, which were primarily 'fast' carbohydrates, such as those found in sugar and bread.


What consequences did this have on our health?


The increase in the percentage of fast carbohydrates in the diet was responsible for people who were more obese with a higher prevalence of illness. It is for good reason that, in 2015, the WHO issued recommendations to limit 'free sugars’. That was an important step in the right direction. However, since Keys, the clear consensus in respect of fat in nutritional science has barely changed. That has been quite literally fatal, as it is responsible for the premature death of many people.


The recommendation is still to eat plenty of carbohydrates and one of the government’s focal points is a reduction in saturated fat consumption. This is despite the meta-analysis of randomised intervention studies that demonstrates that the replacement of saturated fat by linoleic acid causes a nearly significantly higher mortality rate. The same study revealed that the lowering of 'our cholesterol' by means of linoleic acid is associated with increased mortality.


How has this situation with linoleic acid arisen?


Prior to 2015, the saturated fat content of food had to be kept below 10% of energy. In the US, the recommendation is still in place to eat less than 7% of energy from saturated fat. In 1961, the American Heart Association launched the recommendation to consume 5-10% of energy from linoleic acid. Saturated fat then had to be replaced by polyunsaturated vegetable fat, i.e.: linoleic acid. Some of the population did that. Since that time, the linoleic acid level in breastmilk increased by a factor of 2-3.


Since then, the current bottle formula has been full of linoleic acid, because the recommended linoleic acid range for bottle formula is based on the levels present in breastmilk. An interesting aspect is that the fat in breast milk reflects approximately 50-60% of the total energy and 40-60% of that is saturated fat. This latter level can barely be influenced by the mother’s diet. Therefore, based on the 7-10% of energy saturated fat recommendation, breastmilk should actually be banned. Driven by the recommendation to replace saturated fat with polyunsaturated fat, humans 'improved’ the only food that came about through evolution.


What energy percentage of saturated fat do we consume in the Netherlands?


In 2007 – 2010, the average intake of saturated fat in the Netherlands was around 12-13 percent of energy; since 2003 this percentage has not changed significantly. In the Netherlands, milk and dairy products are by far the main sources of saturated fat. However, meta-analyses of observational studies show at best beneficial effects of milk and dairy products on indices for cardiovascular diseases and type 2 diabetes mellitus. RCTs show no potential harmful effects on risk factors associated with circulating fats, blood pressure, inflammation, insulin resistance and vascular function.


It makes no difference whether full-fat or low-fat products are used. A meta-analysis of 21 prospective studies involving 347,747 people also showed no correlation between the total saturated fat consumed and cardiovascular diseases. In a more recent meta-analysis, in healthy people there was no correlation between the consumption of saturated fat and death from all causes, cardiovascular disease, death resulting from cardiovascular disease, ischaemic stroke and type 2 diabetes mellitus.


What is the role of Ancel Keys in this whole story?


With his ‘Seven Countries Study’ Keys was instrumental in the 'cholesterol hypothesis of cardiovascular diseases'. Put briefly: 'LDL cholesterol is bad and HDL cholesterol is good’. No evidence has ever been provided for this, but for many scientists the situation is clear and the discussion is closed. For example, in respect of the ‘Guidelines for a Healthy Diet 2015’, the Health Council accepted the LDL cholesterol as a proven cause of cardiovascular diseases. But in the meantime, the science community is a long way from reaching an agreement.


It is important to properly assess the true value of the arguments of the proponents of the cholesterol hypothesis. The fact that the unstable atherosclerotic plaque contains cholesterol esters doesn’t mean that cholesterol is the cause of atherosclerosis. An important argument is that statins help to reduce the LDL cholesterol and that statins lower the risk of cardiovascular disease. Both observations have undoubtedly been conclusively proven, but that doesn’t mean causality between the LDL cholesterol reduction and the lower risk. Because statins have so-called pleiotropic effects, they do more than lower LDL cholesterol, even though this was the primary reason for studying statins. For example, statins also suppress inflammation. They lower the CRP and, say, the cause and consequence. Back in the 1990s, Ross asserted that atherosclerosis was an inflammatory illness.


But what is the real risk factor for cardiovascular diseases?


This is actually a sub-fraction of the LDL, the so-called 'small dense LDL'. That is the actual risk factor and even that is not in isolation. Indeed, “saturated fat increases the LDL cholesterol”, but that is a half-truth, because this fact should be followed by the fact that, in this case, there is an increase in the larger LDL particles that do not pose a risk and that the HDL cholesterol also rises.


Small dense LDL is accompanied by a decrease of the 'good guy', called HDL, that under these conditions behaves as a 'bad guy'. The wrong lifestyle causes their formation, central to which is 'low-grade inflammation’. Unless we assume that nature is illogical and our evolution is not based on optimising our body in its context, nature surely did not intend to give us cardiovascular diseases.


Anyone who doesn’t eliminate the principles of biology, must acknowledge that cardiovascular diseases are a perfectly normal reaction to an environment/lifestyle chosen by humans which would never have existed in evolution.


How can we turn the tide?


When informing the public about the factors and the hazards of an unhealthy lifestyle, it is important to provide information about the effect of saturated fat and our serum (LDL) cholesterol based on good science. There are now many serious scientists who are taking the lead because they think in terms of the system as a whole. Also striking is that doctors – i.e. people who have direct responsibility for the lives of individual patients – are increasingly making their voices heard and are increasingly exerting their influence.


I hope that I have clarified that the clear consensus about fat is based on misconceptions and is side-lined by the solid principle of a systems approach to biology.



For comprehensive backgrounds and literature reference, see:

1. Muskiet FAJ, Muskiet HHA, Kuipers RS Het faillissement van de verzadigd vethypothese van cardiovasculaire ziektes Ned Tijdschr Klin Chem Labgeneesk 2012; 37: 192-211.

2. Muskiet FAJ. De LDL-cholesterol concentratie heeft zijn status als risicofactor verloren. Ned Tijdschr Klin Chem Labgeneesk 2016; 41: 253-265.

3. Ruiz-Núñez B, Dijck-Brouwer DA, Muskiet FA. The relation of saturated fatty acids with low-grade inflammation and cardiovascular disease.J Nutr Biochem. 2016.