In a recent study published within the journal Advances in Nutrition, researchers critically assessed the impact of assorted dietary elements on blood pressure and hypertension risk through an umbrella review of meta-analyses from each interventional and observational studies.
Review: The role of weight loss program within the prevention of hypertension and management of blood pressure: An umbrella review of meta-analyses of interventional and observational studies. Image Credit: udra11 / Shutterstock
Background
Hypertension (BP) is a number one contributor to cardiovascular diseases and adult mortality. A world prevalence of hypertension of 34% for men and 32% for ladies was observed in 2019, but fewer than half of the treated population had their hypertension controlled. The primary risk aspects include dietary and lifestyle habits, comparable to sodium intake and physical activity. While organizations just like the European Society of Cardiology provide guidelines highlighting diets just like the Mediterranean and Dietary Approaches to Stop Hypertension (DASH), recent studies have delved into specific food groups and nutrients’ effects on BP. Further research is required to assimilate emerging dietary insights and refine current hypertension guidelines.
In regards to the study
The current umbrella review was carried out based on the Joanna Briggs Institute’s methodology and was registered on the International Prospective Register of Systematic Reviews (PROSPERO). A precise literature search spanned databases like PubMed, Embase, Web of Science, and Cochrane Central Register of Controlled Trials until October 2021. The aim was to discover meta-analyses of each randomized controlled trials (RCTs) and observational studies concerning weight loss program and blood pressure. Two researchers worked independently on this search, using specific search terms, specializing in human studies. A 3rd researcher resolved any disagreements in selections.
To avoid duplications, a structured method was used to incorporate meta-analyses. If multiple meta-analyses addressed an identical dietary exposure, essentially the most comprehensive one was chosen based on the variety of primary studies, total sample size, and depth of knowledge provided. Data extracted included writer details, publication 12 months, consequence specifics, intervention type, exposure, study design, variety of participants, result types, heterogeneity evaluation, effect estimates, and potential conflicts of interest. Effect sizes were visually represented using Forest plots, and dietary effects were further grouped by their impact on blood pressure, classified based on the NutriGrade system.
The standard of the included publications was gauged using the Assessment of Multiple Systematic Reviews 2 (AMSTAR 2) tool, examining various critical domains pertinent to the systematic review process. The NutriGrade system, designed to grade evidence in nutrition research, was used to evaluate the standard of evidence for every meta-analysis. This method evaluated multiple quality features of the meta-analyses, with two reviewers independently making assessments and a 3rd resolving any disagreements. The evidence was then rated based on its quality, from high to very low, providing a comprehensive understanding of the collective research on the connection between weight loss program and blood pressure.
Study results
A comprehensive review, employing the PRISMA flowchart, scrutinized 17,099 records, finalizing 175 publications. These encompassed a broad spectrum of dietary aspects, from meat and vegetables to beverages and macronutrients. The primary contributions hailed from Europe, Asia, and North America.
The methodological robustness of the publications displayed variation. In RCTs, high-quality studies constituted 7.5%, with a descending quality observed in 43.2% moderate, 27.4% low, and 21.9% critically low. The observational studies didn’t reach a high-quality rating; 65.5% were deemed moderate, with 27.6% low and 6.9% critically low. Many low-quality studies were critiqued for overlooking grey literature and exhibiting biases.
The NutriGrade system identified limited high-quality RCT meta-analyses. Concerning between-study heterogeneity in RCTs, 6.5% didn’t acknowledge it, while 35.4% reported significant variations. Only 29.6% of RCTs bore a low risk of publication bias, whereas observational studies exhibited diverse risk profiles.
The review explored dietary regimes and their implications on blood pressure. High-quality RCT data suggested diets like DASH and ketogenic contributed positively to blood pressure control. While observational studies proffered weaker evidence for diets comparable to vegan and Mediterranean. Inside the meat, eggs, and fish category, RCTs offered moderate evidence about fish and egg consumption, contrasting with observational studies that presented a lower quality testament for egg and meat intake.
Diving deeper, the NutriGrade system make clear the connection between specific foods and blood pressure. Vegatables and fruits emerged with a moderate quality endorsement, signifying potential blood pressure reduction from foods like blueberries and beetroot. Starch-rich foods garnered mostly low-quality evidence, whereas legumes presented a mixed bag, with pulses being an exception with their moderate evidence. Nuts and seeds, with a special mention of flaxseed, stood out with high-quality proof for his or her blood pressure-lowering capacities. Cocoa, too, had moderate supportive evidence.
Within the herb domain, cinnamon reduced while licorice escalated diastolic blood pressure. Teas received moderate validation for reducing blood pressure, with coffee’s influence remaining ambiguous. Discussions around macronutrients highlighted proteins like L-carnitine and soy protein with favorable evidence. In contrast, the vast majority of fats and oils, barring a number of like Eicosapentaenoic Acid (EPA), exhibited inconsistent results. Minerals also showcased variability; potassium was strongly advocated for blood pressure diminution, whereas calcium and zinc remained inconclusive.