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Rapid response to:


Intake of individual saturated fatty acids and risk of coronary heart disease in US men and women: two prospective longitudinal cohort studies

BMJ 2016; 355 doi: (Published 23 November 2016) Cite this as: BMJ 2016;355:i5796

Rapid Response:

Why are observational studies still being done?

The latest paper by Harvard TH Chan School of Public Health/Unilever observed 10 non-significant associations and 6 very small statistically significant associations between coronary heart disease and energy substitution for individual saturated fatty acids and alternative nutrients.

This followed searches for patterns in two prospective cohort studies (the Nurses' Health Study and the Health Professionals Follow-up Study), from which more than 30 papers for 2016 alone have been generated with Walter C Willet and Frank B Hu as co-authors.

Surely an institution as esteemed as Harvard, would know that epidemiological studies can merely suggest associations, which should then be tested for causation with randomised controlled trials (RCTs). On the subject of dietary fat, epidemiology and dietary interventions have been running in parallel since the 1950s. If the observations being repeatedly made by Harvard had any value, they would have been supported by RCTs and they have not. So when will Harvard admit this and stop this endless stream of non-sense?

Competing interests: ZH writes and publishes books and web content in the field of diet and health.

30 November 2016
zoe harcombe
Independent researcher
Newport Gwent