Urine and Plasma Metabolome of Healthy Adults Consuming the DASH (Dietary Approaches to Stop Hypertension) Diet: A Randomized Pilot Feeding Study

Abstract

We aimed to identify plasma and urine metabolites altered by the Dietary Approaches to Stop Hypertension (DASH) diet in a post-hoc analysis of a pilot feeding trial. Twenty adult participants with un-medicated hypertension consumed a Control diet for one week followed by 2 weeks of random assignment to either Control or DASH diet. Non-missing fasting plasma (n = 56) and 24-h urine (n = 40) were used to profile metabolites using untargeted gas chromatography/mass spectrometry. Linear models were used to compare metabolite levels between the groups. In urine, 19 identifiable untargeted metabolites differed between groups at p < 0.05. These included a variety of phenolic acids and their microbial metabolites that were higher during the DASH diet, with many at false discovery rate (FDR) adjusted p < 0.2. In plasma, eight identifiable untargeted metabolites were different at p < 0.05, but only gamma-tocopherol was significantly lower on DASH at FDR adjusted p < 0.2. The results provide insights into the mechanisms of benefit of the DASH diet.

Keywords: DASH; blood pressure; metabolomics; nutrition; polyphenols.

Figure 1

Study flow chart. Adapted from original published manuscript [6].

Figure 2

Relative Difference in Nominally Significant Metabolites from Untargeted Urine GC/MS during Randomized DASH and Control Feeding Periods. Relative difference represents the ratio of peak areas by GC/MS. Differences are tested using generalized estimating equation models evaluating the difference in log₂ peak areas in non-missing samples obtained during randomized study weeks on either DASH or Control diet. Relative differences re-express absolute log₂ difference coefficients (β) as 2^β. Significance at a false discovery rate (FDR) adjusted p < 0.20 is indicated by an asterisk (*). Metabolites are ordered by statistical significance with the most statistically significant metabolites beginning at the bottom near the x-axis. Several metabolites had between 10–20 imputed values including caffeic acid, gentisic acid, uric acid and threonine.