The “Lipid Hypothesis”
Are you worried about your blood cholesterol (TC) level? For many it is a fact of life (and death) that if you have a high TC level this means an increased risk of dying from heart disease. Hence it follows that steps should be taken to lower it in order to reduce the risks. It is this rationale which underpins the case for using statins and for the dietary advice to reduce the consumption of saturated fats (SFAs) and to increase that of polyunsaturated fats (PUFAs). A recent paper in the BMJ is a further addition to the huge amount of evidence that challenges the validity of this hypothesis (1).
This is a re-examination of the data from the Minnesota Coronary Experiment (MCE) which was a trial done between 1968 and 1973. This was to determine if the replacement of SFAs with a vegetable oil, rich in the PUFA linoleic acid (LA) would reduce the incidence of coronary heart disease (CHD) by lowering the TC. The original report was published in 1989 (sometime after the end of the study!) (2). In this latest report, the researchers had access to data, which had not been used in the preparation of the earlier one. Information was obtained for 2355 individuals with an age range from 20 to 97 years. Slightly more than half were women and 25% were 65 or older. The average TC was 208 mg/100 ml (5.39 mmol/L). In order to lower the TC, the diet was altered by reducing the SFA from 18.5% to 9.2% of Calories. The Increase in PUFA was largely due to LA which increased from 3.4% to 13.2% of Calories. During the study there was also a small increase in the LA content of the control diet from 3.4% to 4.7%.
The researchers have attempted to answer three questions.
Did the MCE intervention lower serum cholesterol?
The answer to this question was a definite YES. There was of 31.2 mg/100mg (0.8 mmol/L). As expected, there was also a small reduction in TC of the controls because of the increase in LA in the diet.
Did the MCE intervention reduce risk of death?
This is the $64,000 question. If the conventional wisdom is correct then there should be a substantial drop in the risk of dying from heart disease. However my big gripe about this is that I need to be sure that there is not an increased risk of dying from some other cause. So I am only interested in the impact on all-cause mortality (ACM). It was found that there was no reduction in ACM for those who changed their diet and there were strong indications that there was actually increased mortality in those aged over 65 years.
Was the change in serum cholesterol related to risk of death?
In contrast to what would be expected according to conventional wisdom, the reduction in TC of 30mg/100mg (0.78 mmol/L) was accompanied by an increase in death rate of 22%. Even more disturbing is that was restricted to those who were over 65 years old. In this group, the ACM was increased by 35%. Post-mortems were done on some of the participants and the results showed that the incidence of myocardial infarcts in those who altered their diet was double that of those in the controls.
Not just an isolated example
While the advocates of the Lipid Hypothesis may try to brush this off as an isolated study, the reality is that it fits in perfectly with lots of other information, which all point to the same conclusion. I have described many different studies on the relationship between TC and ACM in a previous blog (3). I concluded:
“Without exception all-cause mortality is highest in those with the lowest levels of TC. In older people those with the highest cholesterol have the highest survival rates, irrespective of where they live in the world. The picture which emerges is totally consistent.”
The evidence continues to pile up
More recently in June 2016, BMJ Open published a meta-analysis based on 19 carefully selected studies, which involved just over 68,000 participants (4). This highly relevant because the focus is on the LDL-Cholesterol (LDL-C) the so-called “bad” one. The analysis found that there was either a lack of an association or an inverse association between LDL-C and mortality among people older than 60 years. In almost 80% of the total number of individuals, LDL-C was inversely associated with ACM and with statistical significance. To make it quite clear what this means is that those with high values for the LDL-C, the risk of dying (from any cause) is less than with those who have lower values. Or to put it another way, those who comply with the official guidelines for LDL-C are more likely to die than those who are regarded as “at high risk for heart disease” because they have a raised LDL-C.
Results like this have been emerging for years. As long ago as 1992, there was a conference to consider a whole series of investigations which came to similar conclusions (5). These were just brushed aside because they posed a threat to the National Cholesterol Education Program (NCEP) in the USA, which was already in place. The explanation put forward was that the low cholesterol was caused by the incipient disease. This possibility was eliminated by excluding data for people who died in the first 4 or 5 years.
A more likely explanation is that the high cholesterol is beneficial and that low values increase susceptibility to diseases that prove to be fatal. This view is supported by the fact that LDL-C binds to various microorganisms and their toxic products thereby inactivating them. Hence those with high LDL-C would have some protection, which would not apply to those with low values.
The implications of this knowledge are absolutely mind-blowing. If these results are reliable and there is so much from a variety of different sources, they really do have credibility, then it is totally irresponsible to advise them to lower their cholesterol. It is comparable to advising a person with gold-plated final year salary scheme pension to give it up for something that is much more risky. Those in a position to take effective action to address this fiasco, to put it mildly, have been totally irresponsible. Perhaps CORRUPT would be more accurate to describe what is going on. All I can say is that if you are advised to reduce your cholesterol by diet or drugs, then show your adviser the information shown here, which all comes from high quality authoritative sources.
- C E Ramsden (2016) http://www.bmj.com/content/bmj/353/bmj.i1246.full.pdf
- I D Frantz Jr et al. (1989). Arteriosclerosis 9 129-35 doi:10.1161/01.ATV.9.1.129
- V Wheelock http://vernerwheelock.com/179-cholesterol-and-all-cause-mortality/
- U Ravnskov et al (2016) http://bmjopen.bmj.com/content/6/6/e010401.full
- D Jacobs et al (1992) Circulation 86 pp 1046-1060