Adherence
Prospective cohort studies are methodologically superior to case-control studies for investigating diet-disease relationships because they avoid recall bias and reverse causation bias inherent in case-control designs.
For long-term health research, tracking dietary habits over many years in large groups (prospective cohorts) provides more reliable evidence of cause-and-effect than comparing sick and healthy people after the fact (case-control). This is because it avoids the errors of remembering past diets and the influence of disease on current biological markers.
Case-control studies may be flawed by differential bias between cases and controls in the recall of dietary habits, and case-control studies that use biomarkers of diet or metabolism may also be flawed because the markers may be altered by the presence or diagnosis of a tumour. In principle, prospective cohort studies are not subject to these two major forms of bias.
Why this rating
The paper describes a massive, multi-center, long-term prospective cohort (n=519,978), which is the gold standard for observational epidemiology.
Source
European Prospective Investigation into Cancer and Nutrition (EPIC): study populations and data collection
Elio Ríboli et al. · Public Health Nutrition · 2002
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