Theory and performance of substitution models for estimating relative causal effects in nutritional epidemiology.

Background: Estimating relative causal effects (i.e., "substitution effects") is a common aim of nutritional research.

The relatively small contribution of birth weight to blood pressure at age 49-51 years in the Newcastle Thousand Families Study.

Background: Whereas a large number of previous studies suggest an association between birth weight and later blood pressure, others do not. Controversy surrounds the relative importance of these associations, in particular in relation to more modifiable factors in later life. The aim of this study was to investigate the relative contributions of a range of factors from across life to variations in SBP and DBP in the Newcastle Thousand Families Study.