Medical Nutrition Therapy Provided by a Dietitian Improves Outcomes in Adults with Pre-Hypertension or Hypertension: A Systematic Review and Meta-Analysis

Background: Hypertension is an important risk factor for cardiovascular disease. Interventions with dietitians can help modify dietary intake and reduce hypertension risk.

Objective: To examine the research question: In adults with pre-hypertension or hypertension, what is the effect of medical nutrition therapy (MNT) provided by a dietitian on blood pressure (BP), cardiovascular risk and events and anthropometrics compared to standard care or no intervention?

Methods: MEDLINE, CINAHL and Cochrane Central databases were searched for randomized controlled trials (RCTs) published in peer-reviewed journals from 1985-2022. Risk of bias (RoB) was assessed using the version 2 of the Cochrane tool for RCTs. Meta-analyses were conducted using the DerSimonian-Laird random-effects model. Certainty of evidence (COE) was assessed for each outcome using the Grading of Recommendations, Assessment, and Evaluation (GRADE) method.

Results: Forty articles representing 31 RCTs were included and analyzed. MNT provided by a dietitian likely reduces systolic [Mean Difference (MD): -3.63 mmHg (95% confidence interval (CI): -4.35, -2.91)] and diastolic [-2.02 mmHg (-2.56, -1.49)] BP (p<0.001) and body weight [-1.84 kg (-2.72, -0.96), p<0.001], and improves anti-hypertensive medication usage, relative risk of stroke [0.34 (0.14, 0.81), p=0.02] and CVD risk score [standardized mean difference (SMD): -0.20 (-0.30, -0.09), p<0.001] compared to control participants, and COE was moderate. Additionally, MNT may reduce arterial stiffness [SMD: -0.45 (-0.71, -0.19), p=0.008] and waist circumference [-1.18 cm (-2.00, -0.36), p=0.04], and COE was low. There was no significant difference in risk for myocardial infarction between groups. Dietitian interventions reduced BP and related cardiovascular outcomes for adults with pre-hypertension or hypertension.

Conclusion: Dietitians play a critical role in improving cardiometabolic risk factors for adults with elevated BP; thus, improved payment for and access to MNT services has the potential to significantly impact public health.

Registration id and url: This systematic review was registered in the International Prospective Register of Systematic Reviews: PROSPERO# CRD42022351693 (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022351693).