New evidence links low cholesterol with increased risk of cancer and death, and what are we to make of conventional cholesterol guidelines?

At the risk of repeating myself, today I’d like to share with you the results of a study which has found a link between low cholesterol levels and heightened risk of cancer. After all, it was only last Friday that I reported on a recently published study which found precisely the same thing. The study that I report on today has even more interesting revelations for us, I think.

The study in question assessed 6000 diabetics for an average of almost 5 years [1]. In this group of people, the relationship between (supposedly ‘unhealthy’) LDL-cholesterol and risk of cancer was assessed.

The researchers first of all looked at this relationship in just those who were not were not taking statin (cholesterol reducing) medication. Here’s the first thing, the relationship was found to be U-shaped. In other words, both high and low levels of LDL cholesterol were found to be associated with an increased risk of cancer.

And now this is where things get interesting. Because, the lowest risk of cancer (the bottom of the U) was found to correspond to an LDL level of 3.28 mmol/l. (127 mg/dL). It is perhaps interesting to compare this value with the most recent recommendations for LDL levels that came from the National Cholesterol Education Programme in the USA in 2004. This panel recommended that:

For patients at high risk of heart disease LDL should be lower than 2.59 mmol/l (100 mg/dL)

For patients at very high risk of heart disease LDL should be lower than 1.81 mmol/l (70 mg/dL)

But there’s more: The researchers involved in this study went on look at the relative risk of cancer in 3 groups of individuals divided according to their LDL levels. The three ‘bands’ were:

LDL level of less than 2.8 mmol/L (108 mg/dL)

LDL level of between 2.8 up to 3.8 mmol/L (108 – 147 mg/dL)

LDL level of 3.8 mmol/L (147 mg/dL) or above

Compared to those in the middle band, those individuals with lower cholesterol levels were found to be, overall, at a 74 per cent increased risk of cancer.

Those in the higher band were found to be 87 per cent increased risk of cancer.

The researchers went on to add into the mix those who were taking statins (combining statin-takers and non-takers together). This changed the nature of the association between LDL levels and cancer risk, and in particular resulted in a less association between the two at higher cholesterol levels. The authors wrote: Our detailed analysis also indicated that the use of statins had major effects on the association between LDL cholesterol and all-site cancer, obscuring the true nature of the association.

The authors went further though, and analysed not just the risk of cancer, but the overall risk of death, in each of the three LDL-cholesterol bands.

In patients not using statins, and after controlling for certain confounding factors including waist circumference, ‘healthy’ HDL-cholesterol levels and smoking.

The results revealed that:

Compared to those in the middle band, those individuals with lower cholesterol levels were found to be, overall, at a 50 per cent increased risk of death.

Those in the higher band were found to be 56 per cent increased risk of death.

So, in short, what this study shows is that in this group of diabetics, an LDL level of more than 3.8 mmol/L is associated with an increased risk of cancer and overall risk of death, and so is (and this is quite important, I think) an LDL cholesterol level of less than 2.8 mmol/L.

Now, let’s go back to those NCEP LDL-cholesterol guidelines. They are:

For patients at high risk of heart disease LDL should be lower than 2.59 mmol/l (100 mg/dL)

For patients at very high risk of heart disease LDL should be lower than 1.81 mmol/l (70 mg/dL)

Well, according to this latest study, having cholesterol down where the NCEP suggests may not be such a good thing. And this study is not the only one which has found lower levels of cholesterol to be associated with an increased risk of cancer. We had one come out last week, remember. And the authors of this latest study also point to the fact that: Several prospective analyses, including the US National Health and Nutrition Examination Survey [2], have demonstrated an inverse relation between serum total cholesterol and cancer incidence and mortality in the general population.

Now, getting back once again to those NCEP guidelines, even when cardiovascular disease is the focus odes everyone agree that the recommended LDL-levels stand up to scrutiny. The authors of an independent review of basis for these recommendations which appeared in the Annals of Internal Medicine stated: In this review, we found no high-quality clinical evidence to support current treatment goals for [LDL] cholesterol. They went on to say that the recommended practice of adjusting statin dose to achieve recommended cholesterol levels was not scientifically proven to be beneficial or safe [3]. I don’t suppose it will give us any more confidence in these guidelines to know that the NCEP panel was made up of 9 members, all but one of whom had potential financial conflicts of interest that you can read here. And one final thing: curiously, these conflicts of interest were only revealed after the publication of the NCEP recommendations.

References:

1. Yang X, et al. Independent associations between low-density lipoprotein cholesterol and cancer among patients with type 2 diabetes mellitus. Canadian Medical Association Journal. 2008;179(5):427-437

2. Schatzkin A, et al. Serum cholesterol and cancer in the NHANES I epidemiologic followup study. National Health and Nutrition Examination Survey. Lancet 1987;2:298-301.

3. Hayward RA, et al. Narrative review: lack of evidence for recommended low-density lipoprotein treatment targets: a solvable problem. Ann Int Med 2006;145:520-530

9 Responses to New evidence links low cholesterol with increased risk of cancer and death, and what are we to make of conventional cholesterol guidelines?

  1. Cybertiger 28 August 2008 at 6:29 am #

    Byron Richards writing for NaturalNews has been less than complimentary about the behaviours of the cholesterol-industrial complex.

    http://www.naturalnews.com/024001.html

    Of the “statin scam”, he wrote,

    “The insanity must stop. Americans have been conned. Big Pharma and the American Heart Association should be held responsible for past crimes and future intended crimes against the health of our citizens under the false pretense of improved cardiovascular health.”

  2. Methuselah - Pay Now Live Later 28 August 2008 at 1:49 pm #

    At a high level we can bundle together statins, msg, artificial sweeteners and all the other pharma-peddled rubbish being forced down our throats into a single package labelled ‘meddling’. We will in later years appear to our great grand children like the bungling flight pioneers of the 1800s running off cliffs flapping useless wings!

  3. Peter Deadman 29 August 2008 at 1:31 pm #

    I was just reading about the China Project a China-Cornell-Oxford University study of the health & diet of 6500 rural Chinese. The background was that the Chinese had one seventeenth of the coronary heart disease (CHD) of USA citizens and a fifth of the breast cancer. The average cholesterol level in China was 127mg/dl compared to 215mg/dl in the USA. Note the 127 figure is exactly the same as the most beneficial level found in the study above for the lowest level of cancer. The Chinese levels resulted from diet … on average less than half the fat consumption, about a tenth of the animal food consumption and three times the fibre of the average American. What seems to be different from the study above is that within China, the lowest levels of CHD, diabetes ands seven kinds of cancer seemed to correspond almost exactly to the lowest levels of cholesterol.

  4. briannwen 29 August 2008 at 3:35 pm #

    It is great that this blog exists, but how are we to understand how we are to apply this knowledge in practice; We are told that neither high, nor low levels of cholesterol are good for our health, and somewhere in the middle range is, but how does this equate to food! What is the equivalent of .59 mmol/l (100 mg/dL), or 1.81 mmol/l (70 mg/dL) in food? All these studies are made available to us throughout the web, but it seems most things come at a price. Scientific research shows us in one study that the low carb approach is more successful with men than women, and that women reap more benefit from following a diet closer to the Mediterranean diet for weight loss concerns; but what is the composition of the diet in these studies? Is the literature made available to taunt us? How are we to help our selves, and use science if the composition of such diets are not stated?

  5. Liz 29 August 2008 at 5:53 pm #

    This is another example of linear thinking.

    As in

    “Lowering cholesterol is good so lowering it more must be better”

    using this logic one could say

    “two aspirin are good, twenty must be superb”

    or

    “lowering fat reduces calories so the best way to lose weight is to cut out fat”

    But, oh dear, there are millions of people out there trying to do just that (and I wonder what THEIR cholesterol levels are like?)

  6. nonegiven 30 August 2008 at 6:20 pm #

    I wish someone could tell me how to make my cholesterol more healthy, it has always been too low. The lab reports used to put an ‘L’ beside it, they quit doing that but my cholesterol is still the same or lower. I eat a lot of eggs and get probably 25% of my calories from saturated fat alone.

  7. Anna 30 August 2008 at 9:06 pm #

    Peter Deadman,

    Despite the association with the esteemed Cornell University, not everyone thinks The China Study represents objective science at its best. To begin with, TCS is based an interpretation of epidemiological data, which is best used for generating hypotheses and testing them with other means. Epidemiology can never, ever can prove causation.

    If you want to see another view of TCS, you might look up Chris Masterjohn’s excellent review of TCS (easy to find online). You might decide, as many others have, that the “science” behind the author’s conclusions aren’y very rigorous applied, and Campbell is very much biased toward finding justification for a vegetarian diet. That isn’t very objective science. All “research” isn’t necessarily “good” research.

  8. helen 31 August 2008 at 9:14 pm #

    for more reading on the dangers of low cholesterol & the even more dangerous statin drugs see this site it just about says it all
    http://www.ravnskov.nu/cholesterol.htm

    as for all the “chicken littles” in the business of dealing drugs, i mean the health industry or more correctly the illness industry the sooner your terrible legacy to the world ends the better man has never been served by these quacks that peddle drugs & their time may well & truly be coming to an end as the population at large start waking up & taking the responsibility for their own health back into their hands & out of the big business with illness & drugs!!

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