The DASH diet lowers uric acid levels

In a recent study published in Scientific reportsresearchers conducted a meta-analysis to evaluate the effects of the ketogenic diet (KD) and the Dietary Approaches to Stop Hypertension (DASH) diets on serological uric acid (UA) levels.

Study: Effects of Dietary Approaches to Stop Hypertension and Ketogenic Diet Interventions on Serum Uric Acid Concentrations: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.  Image credit: Alexander Rutz / Shutterstock.com Research: Effects of Dietary Approaches to Stop Hypertension and Ketogenic Diet Interventions on Serum Uric Acid Concentrations: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Image credit: Alexander Rutz / Shutterstock.com

Background

Hyperuricemia is a major risk factor for the onset of gout and is associated with cardiometabolic disease.

Weight reduction measures are considered to be key factors in reducing the risk of hyperuricemia, as UA levels often fluctuate with different dietary habits. In fact, dietary treatment has been shown to reverse hyperuricemia and significantly alleviate gout symptoms. Recent studies have linked the DASH diet, which includes vegetables, fruits, moderate protein and low-fat dairy products, with reduced UA.

The KD is a high-fat, moderate-protein, low-carbohydrate diet commonly used for weight loss and the treatment of neurological diseases. Many observational studies have documented transient hyperuricemia in the ketosis stage of KD; however, the relationship between KD and UA levels remains unclear. In addition, changes in serum UA after very low calorie KD (VLCKD) are discussed.

About research

PubMed, Web of Science, Scopus, and Embase databases were searched up to March 2023 without language restrictions for randomized controlled trials (RCTs) in which adults were prescribed DASH or KD diets for at least two weeks. In addition, references to relevant RCTs were manually searched for additional articles.

The Cochrane Risk of Bias Tool for RCTs (RoB-2) was used to assess risks of bias, while the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was used to assess the quality of evidence. Two researchers independently screened the data, and any disagreements were resolved in consultation with two other researchers.

Random effects modeling was performed to calculate the summary effect. Subgroup analysis based on different caloric amounts in the KD was used to identify sources of heterogeneity in the included studies. A sensitivity analysis was also performed to assess the influence of individual RCTs on the pooled estimates.

Only RCTs including adults and comparing the effects of ketogenic or DASH diets on UA ‚Äč‚Äčlevels with control groups were included. RCTs that included pregnant women or individuals with conditions such as epilepsy and malignancies that could alter serological UA levels, those with an intervention period of less than 14 days, and KD studies with unachieved ketosis were excluded from the analysis. In addition, animal or in vitro studies, book chapters, and records with general or incomplete data were excluded.

DASH diet reduces UA levels, KD is not effective

A total of 26,915 records were initially identified. After removing irrelevant and duplicate articles, 13,758 study titles and abstracts were screened, then 257 studies were screened in full text. After applying the eligibility criteria, 10 RCTs were considered in the final analysis, including four and six RCTs that intervened with the DASH diet and KD, respectively.

A pooled estimate of clinical trials of the DASH diet in 590 subjects showed a significant reduction in serological UA after at least 28 days of intervention. In contrast, a pooled evaluation of six KD RCTs documenting data from 267 individuals showed nonsignificant changes in serological UA levels. Similarly, subgroup analysis of the VLCKD RCT yielded nonsignificant reductions in UA.

The DASH diet, which includes foods with a low glycemic index, such as some fruits and dairy products, has been shown to reduce UA levels without changing insulin or glucose levels. Purine-free dairy proteins, such as lactalbumin and casein, as well as other components of the DASH diet, such as vitamin C, have been found to have UA-lowering effects.

Lower UA levels after VLCKD may be due to the body’s limited ability to maintain circulating ketone bodies during fasting or near-fasting diets, limiting their excretion through the kidneys. Differences in caloric, fat, and carbohydrate intake across trials may have contributed to significant differences in KD studies.

Conclusions

The DASH diet appears to lower blood UA levels; therefore, integrating this diet into treatment regimens for individuals with hyperuricemic conditions, including gout, may provide beneficial results. Although KD did not affect blood UA levels, very low-calorie KD appears to provide a UA-lowering effect that warrants further investigation.

Future studies, including larger sample sizes and more consistent populations, could evaluate dose-response relationships between the DASH diet and serological UA levels and other diets, including the Mediterranean and vegetarian diets, to determine which diet is best for lowering serum UA levels.

Journal reference:

  • Gohari, S., Ghobadi, S., Jafari, A. and others. (2023). Effect of dietary approach to stop hypertension and ketogenic diet intervention on serum uric acid concentrations: a systematic review and meta-analysis of randomized controlled trials. Scientific reports 13(10492). doi:10.1038/s41598-023-37672-2

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