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).

The effectiveness of medical nutrition therapy provided by a dietitian in adults with prediabetes: a systematic review and meta-analysis

BACKGROUND

A total of 374 million adults worldwide are living with prediabetes, 70% of whom will develop type 2 diabetes mellitus (T2DM) in their lifetime. Medical nutrition therapy (MNT) provided by a dietitian, such as that found in lifestyle interventions, has the potential to improve glycemic control and prevent progression to T2DM.

OBJECTIVES

The objective of this systematic review was to examine the effectiveness of MNT provided by a dietitian, compared with standard care, on glycemic, cardiometabolic, and anthropometric outcomes in adults with prediabetes.

METHODS

Searches were conducted for randomized controlled trials (RCTs) published between 1995 and 2022 using electronic databases MEDLINE, CINHAL, and Cochrane Central. The risk of bias was assessed using version 2 of the Cochrane risk-of-bias tool for RCTs. Meta-analyses were conducted using a random-effects model. The certainty of evidence was assessed for each outcome using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) method, and a summary of findings table was created using the GRADEpro Guideline Development Tool.

RESULTS

Thirteen RCTs were included in the analysis, showcasing a variety of MNT interventions delivered by dietitians. Intervention durations ranged from 3 to 24 mo. Compared with standard care, MNT improved hemoglobin A1c (HbA1c) (mean difference [95% confidence interval]: -0.30% [-0.49, -0.12]) and fasting blood glucose (FBG) (-4.97 mg/dL [-6.24, -3.71]). Statistically significant improvements were found in anthropometrics (weight, body mass index, and waist circumference), cholesterol (total, high-, and low-density lipoproteins), and blood pressure (systolic and diastolic). No significant effect was found on T2DM or triglycerides. The certainty of evidence was moderate for FBG and low for HbA1c and incidence of T2DM.

CONCLUSIONS

In adults with prediabetes, MNT was effective in improving glycemic outcomes, anthropometrics, blood pressure, and most lipid levels. However, most studies had a risk of bias because of the randomization process or deviations from intended interventions. MNT plays a key role in improving cardiometabolic risk factors in adults with prediabetes.

TRIAL REGISTRATION NUMBER

This study was registered with the registration ID #351421, available from https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=351421.