In spite of a broad range of data supporting the diet-heart hypothesis, the importance of diet is often challenged. Cited in this controversy are population-based, cross-sectional studies which have provided conflicting data. Several studies including an early report from Framingham and the Tecumseh Study have failed on cross-sectional analysis to link dietary variables to serum cholesterol, lipoproteins or coronary heart disease rates. The genetic and possible dietary homogeneity in these populations and methodological weaknesses inherent in singe serum cholesterol and dietary assessments have been posed as possible explanations for these differing results.