Relative efficacy of differential methods of dietary advice: a systematic review

Dietary advice to lower blood cholesterol may be given by a variety of means. The relative efficacy of the different methods is unknown.

The objective was to assess the effects of dietary advice given by dietitians compared with advice from other health professionals, or self-help resources, in reducing blood cholesterol in adults.

We performed a systematic review, identifying potential studies by searching the electronic databases of the Cochrane Library, MEDLINE, EMBASE, CINAHL, Human Nutrition, Science Citation Index, and Social Sciences Citation Index. We also hand-searched relevant conference proceedings, reference lists in trial reports, and review articles. Finally, we contacted experts in the field. The selection criteria included randomized trials of dietary advice given by dietitians compared with advice given by other health professionals or self-help resources. The main outcome was difference in blood cholesterol between the dietitian group compared with other intervention groups. Inclusion decisions and data extraction were duplicated.

Eleven studies with 12 comparisons met the inclusion criteria. Four studies compared dietitians with doctors, 7 with self-help resources, and 1 with nurses. Participants receiving advice from dietitians experienced a greater reduction in blood total cholesterol than those receiving advice from doctors (-0.25 mmol/L, 95% CI -0.37, -0.12 mmol/L). There was no statistically significant difference in change in blood cholesterol between dietitians and self-help resources (-0.10 mmol/L, 95% CI -0.22, 0.03 mmol/L).

Dietitians appeared to be better than doctors at lowering blood cholesterol in the short to medium term, though the difference was small (about 4%), but there was no evidence that they were better than self-help resources or nurses.