BMJ  2006;333:148-149 (15 July), doi:10.1136/bmj.333.7559.148-b

Letter

Cholesterol and risk of stroke

The Japanese comparison

EDITOR—Yet again, a potential relation between low cholesterol concentrations and haemorrhagic stroke is dismissed.¹ Yet again, a causal relation between high cholesterol concentrations, ischaemic stroke, and coronary heart disease is (apparently) confirmed.

Yet data from Japan directly contradicts Ebrahim et al's conclusions. From 1958 to 1995 fat consumption increased from 5% to 20% of the total daily energy consumption, and cholesterol concentrations rose from 3.9 mmol/l to 5.0 mmol/l.² During this period the rate of stroke (combined) fell from 1344/100 000/year to 205/100 000/year in those aged 60-69. This is a 6.5-fold reduction in the rate of stroke.³ (There was also a decrease in death rate from coronary heart disease.)

The possibility that increased fat consumption was the causal factor in reducing the rate of stroke is strongly supported by a study in Stroke, which concluded that: "A high consumption of animal fat and cholesterol was associated with a reduced risk of cerebral infarction death."⁴

A low cholesterol concentration has been found to be associated with an increased risk of haemorrhagic stroke in many different studies. And when cholesterol concentrations rose dramatically in Japan the rate of stroke plummeted.

A low cholesterol concentration may well be a "causal" risk factor for haemorrhagic stroke, and the connection cannot be dismissed by this study.

Benchill Medical Centre, Wythenshawe M22 7WP malcolmken{at}doctors.org.uk

---

Competing interests: MEK is a member of the international network of cholesterol sceptics (THINCS).

References

1. Ebrahim S, Sung J, Song YM, Ferrer RL, Lwalor DA, Davey Smith G. Serum cholesterol, haemorrhagic stroke, ischaemic stroke, and myocardial infarction: Korean national health system prospective cohort study. BMJ 2006;333: 22-7. (1 July.)[Abstract/Free Full Text]
2. Adachi H, Hino A. Trends in nutritional intake and serum cholesterol levels over 40 years in Tanushimaru, Japanese men. J Epidemiol 2005;15: 85-9.[CrossRef][ISI][Medline]
3. Liu L, Ikeda K, Yamori Y. Changes in stroke mortality rates for 1950 to 1997. A great slowdown of decline trend in Japan. Stroke 2001;32: 1745.[Abstract/Free Full Text]
4. Sauvaget C, Nagano J, Hayashi M, Yamada M. Animal protein, animal fat, and cholesterol intakes and the risk of cerebral infarction mortality in the adult health study. Stroke 2004;35: 1351.

Related Article

Serum cholesterol, haemorrhagic stroke, ischaemic stroke, and myocardial infarction: Korean national health system prospective cohort study

Shah Ebrahim, Joohon Sung, Yun-Mi Song, Robert L Ferrer, Debbie A Lawlor, and George Davey Smith
BMJ 2006 333: 22. [Abstract] [Full Text] [PDF]