The Cholesterol Myth

Part 4: Dangers of Low Blood Cholesterol

Nature has taken good care that theory should have little effect on practice.
Samuel Johnson

Low blood cholesterol and cancer

So far advertisers and news media have concentrated on the supposed danger from high levels of blood cholesterol. The dangers of low blood cholesterol levels have largely been ignored.

Countries with diets high in saturated fats also tend to have high levels of colon cancer. In 1974 a review of the Framingham data and those from Keys' 'Seven Countries' study was carried out. It was expected to show that the cancer could also be blamed on high blood cholesterol. However, the baffled researchers found the opposite: those with the cancer had cholesterol levels that were lower than average.

Reports of more than twenty studies into the relation between blood cholesterol and cancer have been published since 1972. Most have reported an association between low blood cholesterol and cancer. The authors of the Renfrew and Paisley Study conclude:

"it may be a mistake to assume that dietary advice given to the general population to reduce the intake of saturated fat will necessarily reduce overall mortality."

In a study from the USA published in 1990, changes in blood cholesterol over time were studied in patients with colon cancer. The doctors found that there had been an average thirteen percent decline in blood cholesterol levels in the ten years prior to diagnosis of the cancer compared with an average increase of two percent in the control group. Both those with the cancer and those free from it had similar blood cholesterol levels initially. It is possible that the decline in blood cholesterol levels was a result of the cancer, not the cause of it, but this is ruled out by the investigators. They compare cholesterol studies with apparently contrary findings and show that in reality they are consistent. Comparing those that reported normal or high cholesterol readings several years prior to diagnosis with others where, at the time of diagnosis, levels were low, they conclude that it was a long term lowering of blood cholesterol levels that gave rise to the cancers. Interestingly, the average blood cholesterol level of those who developed the cancers declined to an average 5.56 mmol/l and yet the British government's Health of the Nation strategy still aims to reduce everyone's levels to below 5.2 mmol/l.

Low cholesterol means more strokes

Published at about the same time was a very large study in Japan, covering two decades, which concluded that low levels of blood cholesterol also increase the incidence of stroke.

Over the past few decades, Japan has experienced a rapid change in its living and eating patterns. The Japanese are eating more total fat, saturated fatty acids and cholesterol, animal fats and protein, and less rice and vegetables. This has provided a unique opportunity for a large-scale, natural experiment into the effects of those changes.

Investigators have shown that this change to Western and urban eating patterns, departing as it does from centuries old traditions, has been accompanied by a general lowering of blood pressure and a large decline in the incidence of stroke deaths and cerebral haemorrhage between the 1960s and the 1980s. They attribute this decline to an increase in blood cholesterol levels over the period. Supporting their findings were the results of a follow-up of 350,000 men screened for the MRFIT in the United States that showed that the risk of death from cerebral haemorrhage in middle-aged men was six times greater if they had low blood cholesterol levels.

On Christmas Eve, 1997, yet one more study's results were headlined in the press. The Framingham researchers said that "Serum cholesterol level is not related to incidence of stroke . . ." and showed that for every three percent more energy from fat eaten, strokes would be cut by fifteen percent. They conclude:

"Intakes of fat and type of fat were not related to the incidence of the combined outcome of all cardiovascular diseases or to total or cardiovascular mortality."

So, after forty-nine years of research, they are still saying that there is no relation between a fatty diet and heart disease. The evidence now is clear and unequivocal: animal fats are not harmful.

Two more studies, which considered total blood cholesterol levels and mortality in the elderly, were published in the Lancet almost simultaneously in 1997. In the first, scientists working at the Leiden University Medical Centre found that

"each 1 mmol/l increase in total cholesterol corresponded to a 15% decrease in mortality".

Similarly, doctors at Reykjavik Hospital and Heart Preventive Clinic in Iceland noted that the major epidemiological studies had not included the elderly. They too studied total mortality and blood cholesterol in the over 80s to show that men with blood cholesterol levels over 6.5 had less than half the mortality of those whose cholesterol level was around the 5.2 we are told is "healthy".

Low cholesterol and Alzheimer's Disease

Approximately half of the brain is made up of fats. Dr. F. M.Corrigan and colleagues, writing in 1991 about the relief of Alzheimer's Disease, ask that "strategies for increasing the delivery of cholesterol to the brain should be identified". In the fight against Alzheimer's disease, they recommend increasing fat intake.

And at the other end of life

In 1991 the US National Cholesterol Education Programme recommended that children over two years old should adopt a low-fat, low-cholesterol diet to prevent CHD in later life. A table showing a good correlation between fat and cholesterol intakes and blood cholesterol in seven to nine-year-old boys from six countries supported this advice. What it did not show, however, was the strong correlation between blood cholesterol and childhood deaths in those countries. These are at Table V. As is clearly demonstrated, the death rate rises dramatically as blood cholesterol levels fall. So for children too, low blood cholesterol is unhealthy.

Table V: Blood cholesterol and mortality in under-5s in six countries
	Blood cholesterol	Childhood deaths
Finland	4.9	7
Netherlands	4.5	9
USA	4.3	12
Italy	4.1	12
Philippines	3.8	72
Ghana	3.3	145

Low blood cholesterol, aggressive behaviour and suicide

Lastly, since 1992, several observers have noted increases in suicides among those undertaking cholesterol-lowering dietary regimes. Decreases in blood cholesterol cause decreases in serotonin receptors leading to increased microviscosity and affecting the balance of cerebral lipid metabolism which could have profound effects on brain function.

In institutions, aggressive people and those with antisocial personality have been found to have lower blood cholesterol levels than normal: Typically 5.04mmol/l vs 6.02mmol/l. Mental patients with high blood cholesterol (7.55mmol/l) were less regressed and withdrawn than those with lower (4.80mmol/l).

Dr Matthew G Dunnigan of Stobhill General Hospital, Glasgow, concludes that:

"Without definite data on all-cause mortality and with current unresolved concerns about excess deaths from non-cardiac causes in RCTs, decisions to embark on lifelong lipid lowering drug treatment in most patients with primary hypercholesterolaemia depend on the doctor's interpretation of available evidence. As in other situations in which certainty is illusory, this varies from evangelical enthusiasm for lowering lipid concentrations to therapeutic nihilism."

References:

A J McMichael, et al. Dietary and endogenous cholesterol and human cancer. Epidemiol Rev. 1984; 6: 192.
F Cambien, et al. Total serum cholesterol and cancer mortality in a middle aged male population. Am J Epid . 1980; 112: 388.
M R Garcia-Palmieri, et al. An apparent inverse relationship between serum cholesterol and cancer mortality in Puerto Rico. Am J Epid. 1981; 114: 29.
D Kozarevic, et al. Serum cholesterol and mortality: the Yugoslavian cardiovascular diseases study. Am J Epid . 1981; 114: 21.
R A Hiatt, B H Fireman. Serum cholesterol and the incidence of cancer in a large cohort. J Chronic Dis . 1986; 39: 861.
A Schatzkin, et al. Serum cholesterol and cancer in the NHANES I epidemiologic follow up study. Lancet. 1987; ii: 298.
A Kagan, et al. Serum cholesterol and mortality in a Japanese-American population: the Honolulu heart program. Am J Epid. 1981; 114: 11.
C G Isles, et al. Plasma cholesterol, coronary heart disease and cancer in the Renfrew and Paisley survey. BMJ. 1989; 298: 920.
S J Winawer, et al. Declining Serum Cholesterol Levels Prior to Diagnosis of Colon Cancer. JAMA . 1990; 263 (15): 2083.
Takashi Shimamoto, et al. Trends for Coronary Heart Disease and Stroke and Their Risk Factors in Japan. Circulation . 1989; 3: 503.
M W Gillman, et al. Inverse association of dietary fat with development of ischemic stroke in men. JAMA 1997; 278: 2145.
AWE Weverling-Rijnsburger, et al. Total cholesterol and risk of mortality in the oldest old. Lancet 1997; 350: 1119-23.
A Jonsson, H Sigvaldason, N Sigfusson. Total cholesterol and mortality after age 80 years. Lancet . 1997; 350: 1778-9.
J Foreman. Cholesterol curb urged for children over 2. The Boston Globe 9 April 1991: 1, 4.
Child mortality under age 5 per 1,000. 1992 Britannia Book of the Year. Encyclopaedia Britannica, Chicago.
F M Corrigan, et al. Dietary supplementation with zinc sulphate, sodium selenite and fatty acids in early dementia of Alzheimer's Type II: Effects on lipids. J Nutr Med 1991; 2: 265-71.
H Engleberg . Low serum cholesterol and suicide. Lancet 1992; 339: 727-9
Modai I, Valevski A, Dror S, Weizman A. Serum cholesterol levels and suicidal tendencies in psychiatric inpatients. J Clin Psychiatry 1994; 55:6; 252-4
Dursun SM, Burke JG, Reveley MA. Low serum cholesterol and depression. Br Med J 1994; 309: 273-4.
MG Dunnigan. The problem with cholesterol: No light at the end of this tunnel? Br Med J 1993; 306: 1355-6.

Return to Part 3: The Bran Wagon | Part 5: Cholesterol-lowering Drugs

See also www.Cholesterol-and-Health.org.uk, an easy to read website about this whole topic from what cholesterol is, why you need it, and how it is made in the body, to what happens if you take cholesterol-lowering drugs such as statins.

Last updated 18 September 2000

"One must attend in medical practice not primarily to plausible theories but to experience combined with reason." Hippocrates

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