a1 Department of Diabetes and Endocrinology, Salford Royal Hospitals NHS Trust, Hope Hospital, Stott Lane, Salford M6 8HD, UK
a2 Nutritional Epidemiology Group and
a3 Department of Psychology, University of Leeds, 71–75 Clarendon Road, Leeds, LS2 9P, UK
There are two key methods in which fat intake may be manipulated; the ‘substitution model’ and the ‘reduction model’. However insufficient information is known about the mechanisms of dietary fat reduction in individuals who have successfully reduced their fat intake, to be clear as to which strategy offers the greatest chance of success. Our objective was to ascertain the most effective dietary intervention for improving cardiovascular risk profile. Eighty female volunteers (high fat consumers) were recruited. Each subject was randomly allocated into one of the following groups. Substitution of high-fat foods was made with reduced-fat products, by the reduction of high-fat foods, by a combination of substitution and reduction strategies, or no advice was given. Each intervention lasted 3 months. Anthropometric measures and fasting blood samples were taken at baseline and follow-up. The substitution intervention resulted in weight loss (mean −1.4 (95% CI −2.4, −0.2) kg) and reduced percentage body fat (mean −1.3 (95% CI −2.0, −0.5)%). There was no significant weight change with the other interventions. Fasting triacylglycerols (−0.2 (SEM 0.07) mM; P=0.04), cholesterol and C-reactive protein (CRP) levels (0.8 (SEM 0.2) mg/l; P=0.04) fell with the substitution intervention, but not with the other interventions. Insulin-like growth factor-1 increased with both substitution and reduction (P=0.02). There was no significant change in fasting insulin or glucose with any intervention. The substitution model of dietary intervention is effective even over a relatively short interval of time in reducing fasting total cholesterol, triacylglycerols and CRP. Although the group size for the present study was small and involved females only, it has significant implications for population intervention strategies.
(Received February 08 2004)
(Revised June 01 2004)
(Accepted July 16 2004)