Effect of dark chocolate on renal tissue oxygenation as measured by BOLD-MRI in healthy volunteers

Pruijm, Menno; Hofmann, Lucie; Charollais-Thoenig, Julie; Forni, Valentina; Maillard, Marc; Coristine, Andrew; Stuber, Matthias; Burnier, Michel; Vogt, Bruno (2013). Effect of dark chocolate on renal tissue oxygenation as measured by BOLD-MRI in healthy volunteers. Clinical nephrology, 80(3), pp. 211-217. Dustri-Verlag 10.5414/CN107897

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BACKGROUND

Cocoa is rich in flavonoids, has anti-oxidative properties and increases the bioavailability of nitric oxide (NO). Adequate renal tissue oxygenation is crucial for the maintenance of renal function. The goal of this study was to investigate the effect of cocoa-rich dark chocolate (DC) on renal tissue oxygenation in humans, as compared to flavonoid-poor white chocolate (WC).

METHODS

Ten healthy volunteers with preserved kidney function (mean age ± SD 35 ± 12 years, 70% women, BMI 21 ± 3 kg/m2) underwent blood oxygenation level-dependent magnetic resonance imaging (BOLD-MRI) before and 2 hours after the ingestion of 1 g/kg of DC (70% cocoa). Renal tissue oxygenation was determined by the measurement of R2* maps on 4 coronal slices covering both kidneys. The mean R2* (= 1/T2*) values in the medulla and cortex were calculated, a low R2* indicating high tissue oxygenation. Eight participants also underwent BOLD-MRI at least 1 week later, before and 2 hours after the intake of 1 g/kg WC.

RESULTS

The mean medullary R2* was lower after DC intake compared to baseline (28.2 ± 1.3 s-1 vs. 29.6 ± 1.3 s-1, p = 0.04), whereas cortical and medullary R2* values did not change after WC intake. The change in medullary R2* correlated with the level of circulating (epi)catechines, metabolites of flavonoids (r = 0.74, p = 0.037), and was independent of plasma renin activity.

CONCLUSION

This study suggests for the first time an increase of renal medullary oxygenation after intake of dark chocolate. Whether this is linked to flavonoid-induced changes in renal perfusion or oxygen consumption, and whether cocoa has potentially renoprotective properties, merits further study.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Department of Dermatology, Urology, Rheumatology, Nephrology, Osteoporosis (DURN) > Clinic of Nephrology and Hypertension 04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > Unit Childrens Hospital > Forschungsgruppe Nephrologie / Hypertonie
UniBE Contributor:	Hofmann, Lucie, Vogt, Bruno
Subjects:	600 Technology > 610 Medicine & health
ISSN:	0301-0430
Publisher:	Dustri-Verlag
Language:	English
Submitter:	Lucie Hofmann
Date Deposited:	18 Mar 2014 14:41
Last Modified:	05 Dec 2022 14:29
Publisher DOI:	10.5414/CN107897
PubMed ID:	23557792
URI:	https://boris.unibe.ch/id/eprint/42776