A Dark Brown Roast Coffee Blend Is Less Effective at Stimulating Gastric Acid Secretion in Healthy Volunteers Compared to a Medium Roast Market Blend

1370 DOI 10.1002/mnfr.201300890 Mol. Nutr. Food Res. 2014, 58, 1370–1373

FOOD &FUNCTION A dark brown roast coffee blend is less effective at stimulating gastric acid secretion in healthy volunteers compared to a medium roast market blend

Malte Rubach1,2∗, Roman Lang3∗, Gerhard Bytof 4, Herbert Stiebitz4, Ingo Lantz4, Thomas Hofmann3 and Veronika Somoza1,2,5

1 German Research Center for Food Chemistry, Freising, Germany 2 Department of Food Science, University of Wisconsin, Madison, WI, U.S.A. 3 Chair of Food Chemistry and Molecular and Sensory Science, Technische Universitat¨ Munchen,¨ Freising, Germany 4 Tchibo GmbH, Hamburg, Germany 5 Department of Nutritional and Physiological Chemistry, University of Vienna, Vienna, Austria

Coffee consumption sometimes is associated with symptoms of stomach discomfort. This work Received: November 26, 2013 aimed to elucidate whether two coffee beverages, containing similar amounts of caffeine, but Revised: January 7, 2014 differing in their concentrations of ␤N-alkanoyl-5-hydroxytryptamides (C5HTs), chlorogenic Accepted: January 8, 2014 acids (CGAs), trigonelline, and N-methylpyridinium (N-MP) have different effects on gastric acid secretion in healthy volunteers. The intragastric pH after administration of bicarbonate with/without 200 mL of a coffee beverage prepared from a market blend or dark roast blend was analyzed in nine healthy volunteers. Coffee beverages were analyzed for their contents of C5HT, N-MP, trigonelline, CGAs, and caffeine using HPLC-DAD and HPLC-MS/MS. Chem- ical analysis revealed higher concentrations of N-MP for the dark brown blend (87 mg/L) compared to the market blend coffee (29 mg/L), whereas concentrations of C5HT (0.012 versus 0.343 mg/L), CGAs (323 versus 1126 mg/L), and trigonelline (119 versus 343 mg/L) were lower, and caffeine concentrations were similar (607 versus 674 mg/mL). Gastric acid secretion was less effectively stimulated after administration of the dark roast blend coffee compared to the market blend. Future studies are warranted to verify whether a high ratio of N-MP to C5HT and CGAs is beneﬁcial for reducing coffee-associated gastric acid secretion.

Keywords: Chlorogenic acids / Coffee / ␤N-alkanoyl-5-hydroxytryptamides / N-methylpyridinium / Telemetric gastric pH measurement

Additional supporting information may be found in the online version of this article at the publisher’s web-site

Freshly prepared coffee brew is widely appreciated for its intake [1]. Although the mechanism of action is not fully attractive aroma and its stimulating effects on the cen- understood yet, epidemiological data provide evidence that tral nervous system. Some consumers, however, experience gastric discomfort or heartburn after food intake might be symptoms of gastric discomfort like heartburn after coffee associated with obesity and life style factors, such as to- bacco or coffee consumption [2]. Scientiﬁc evidence for pu- tative coffee components affecting gastric acid secretion in Correspondence: Professor Veronika Somoza, Department of Nu- humans is also scarce. Steam-treatment of roasted coffee tritional and Physiological Chemistry, University of Vienna, Al- thanstrasse 14 (UZA II), A-1090 Vienna, Austria beans in combination with modiﬁed roasting conditions Fax: +43-1-4277-9-706 has been hypothesized to reduce stomach-irritating com- E-mail: [email protected] pounds, namely caffeine, chlorogenic acids (CGAs), and ␤N-alkanoyl-5-hydroxytryptamides (C5HTs) [3–7]. In rodents, Abbreviations: AUC, area under the curve; CGAs, chlorogenic acids; C5HTs, ␤N-alkanoyl-5-hydroxytryptamides; HGT-1 cells, ∗ human gastric tumor cells; N-MP, N-methylpyridinium These authors have contributed equally to this study.

C 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.mnf-journal.com Mol. Nutr. Food Res. 2014, 58, 1370–1373 1371 administration of a coffee beverage containing high amounts Gastric acid secretion in the study subjects was analyzed of C5HTs induced ulcer formation, whereas no ulcers were by means of the telemetric Heidelberg Detection System, as detected in rats that received a steam-treated, C5HTs-depleted described previously [19]. Briefly, the system consists of a coffee beverage [3]. The pivotal role of C5HTs in stimulating pH-sensitive capsule (called Heidelberg capsule) that, after gastric acid secretion was confirmed in previous studies of being swallowed, sends a signal to a recorder connected to a our own group, using, first, an activity-guided approach [8,9] computer. In order to analyze a decrease in the gastric pH and, second, a multiparametric approach [10] in human gas- induced by acid secretion, 2 mL of a saturated sodium bi- tric tumor cells (HGT-1 cells). Treatment of HGT-1 cells carbonate solution (NaHCO3) is administered. This alkaline with C5HTs in coffee representative concentrations not only challenge triggers a rise in stomach pH and subsequently induced proton secretion, but also induced the expression leads to the secretion of gastric acid. of prosecretory genes, for example, those encoding for the Each volunteer completed four interventions at four in- H+,K+-ATPase alpha-subunit or the acetylcholine receptor dividual visits. At the first visit, subjects were administered

CHRM3, and prosecretory EGFr signaling pathways. Beyond 2mLNaHCO3 solely (visit 1). For testing the effect of the C5HTs, caffeine also effectively stimulated mechanisms of samples, the subjects received, at consecutive visits, the alka- gastric acid secretion, whereas N-methylpyridinium (N-MP) line solution, and, 5 min later, either 200 mL of tap water as inhibited not only proton secretion but also prosecretory path- volume control (visit 2), 200 mL of the market blend coffee ways in HGT-1 cells [10]. N-MP is formed from trigonelline brew (visit 3), or 200 mL of the dark brown blend coffee brew upon roasting of coffee beans [11, 12], and has been shown (visit 4). Initial and maximum intra-gastric pH values as well to have chemopreventive and antioxidative activities in vitro as the change in pH per minute (⌬pH/min) were analyzed. and in vivo [13–15], and to downregulate the expression of the Further experimental details are given in the Materials and gastrin-receptor, which is involved in the molecular mecha- methods section of the Supporting Information. nism inducing gastric acid secretion in parietal cells [16]. No differences were detected for the intragastric pH af- However, previous studies demonstrated that N-MP most ter administration of the bicarbonate solution solely (2 mL), effectively decreased proton secretion in HGT-1 cells when and the combination of bicarbonate (2 mL) and 200 mL of applied in biomimetic mixtures of a coffee beverage, sug- water (pHinitial 0.53 ± 0.09 versus 0.54 ± 0.13; pHmax 5.52 ± gesting that not a single constituent rather than the relative 0.40 versus 6.14 ± 0.66; ⌬pH/min 0.52 ± 0.22 versus 0.38 proportion of coffee constituents determines the beverage’s ± 0.20). Administration of the coffee beverages in addition potential to stimulate gastric acid secretion [10]. This hypothe- to the bicarbonate solution resulted in marked differences sis is supported by findings from Weiß et al. [17] who reported in gastric acid response compared to ingestion of the bicar- that bean processing, affecting the concentrations of a large bonate solution alone: Administration of the market blend variety of coffee constituents, had a more pronounced im- coffee increased gastric acid secretion, whereas intake of the pact than individual compounds discriminated by applying a dark brown blend resulted in a retarded gastric acid secretion principal component analysis. However, mechanistic studies compared to bicarbonate administration. Thus, the gastric from our group indicate that the quantitative ratio of N-MP acid response differed between both coffee beverages, with to C5HTs and CGAs in a coffee beverage might play a crucial the market blend more effectively stimulating gastric acid se- role for its acid stimulatory potential [10,18]. To prove this hy- cretion compared to the dark brown blend. A typical gastro- pothesis, we here performed a randomized, double-blinded gram from one volunteer is shown in Fig. 1. Mean ⌬pH/min intervention in nine healthy volunteers (two males, seven fe- values calculated from gastrograms of all study subjects after males, mean age 25 ± 2 years, habitual coffee consumption administration of bicarbonate, market blend and dark brown of 2–3 cups of regular coffee per day, no Helicobacter pylori blend revealed 0.52 ± 0.22, 0.97 ± 0.36, and 0.26 ± 0.17, infection) who were administered a bolus of 200 mL of a cof- respectively. fee beverage prepared either from a market blend of equal Not only the ⌬pH/min, which indicates the acid secretion amounts of five of the brand leading roasts in Germany (all over time, but also the time needed to reach the initial pH Arabica blends), resulting in a medium brown roast color, prior to administration of the bicarbonate solution was sig- or 200 mL of a dark brown blend prepared from dewaxed nificantly different after administration of both coffees. For Arabica coffee beans, yielding a dark roast coffee product. the market blend, a shorter (p < 0.05) restoring time index of Whereas caffeine concentrations analyzed (cf. Materials and 0.58 ± 0.17 compared to the dark brown blend (0.81 ± 0.21) methods in Supporting Information) in the market blend was calculated (Fig. 2A). In agreement with these findings, (674 mg/L) and the dark brown blend (607 mg/L) were compa- area under curve (AUC) values calculated from the individual rable, the dark brown blend contained higher concentrations response curves over time also indicated a less stimulating of N-MP (87 versus 29 mg/L), but lower amounts of C5HTs effect (p < 0.05) of the dark brown blend (AUC of 0.49 ± 0.23) (0.012 versus 0.343 mg/L), CGAs (323 versus 1126 mg/L), compared to the market blend (AUC 0.25 ± 0.26; Fig. 2B). and trigonelline (119 versus 343 mg/L). With these compo- These results clearly support our hypothesis that a dark sitional differences, we hypothesized the dark brown blend brown blend coffee less effectively stimulates gastric acid beverage to be less effective in stimulating acid secretion in secretion in healthy volunteers compared to a lighter mar- nine healthy volunteers than the market blend beverage. ket blend beverage. Although these results do not provide

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Figure 1. Typical gastrogram of a healthy volunteer after application of bicarbonate, the market blend, or the dark brown blend coffee. conclusive evidence that the ratio of N-MP to C5HTs and CGAs is predicative for the gastric acid stimulating potential of a coffee beverage, we further hypothesize that high concentrations of N-MP in combinations with low concen- Figure 2. Indexed time needed to reach the initial gastric pH and trations of C5HTs and CGAs might be beneficial for sub- indexed area under the curve (AUC) after application of the re- jects who react to coffee consumption with increased gastric spective coffee beverage in healthy volunteers. Statistics: paired acid secretion. From a mechanistic point of view, this hy- Student’s t-test, one-sided market blend versus dark brown blend (*p < 0.05). pothesis is supported by previous studies in which N-MP was identified as an antisecretory constituent [20]. More- over, N-methylnicotinamide, another pyridine derivative, was shown to exhibit an anti-ulcerogenic potential [21]. In con- beverage, in combination with a technological procedure that trast, high concentrations of C5HTs may increase gastric reduces the concentrations of C5HTs and CGAs may result in acid secretion, as revealed by in vitro data that indicate the a product that is less active in stimulating gastric acid secre- chain length of the corresponding fatty acid linked to the 5- tion than a regular coffee with a low quantitative ratio of N-MP hydroxytryptamide being more important for the structure to C5HTs and CGAs. However, evidence-based confirmation specific effect than the degree of saturation [9]. Although in in vivo studies employing administration of single sub- structure-specific effect for C5HTs in vivo are lacking, Fehlau stances and their mixtures in concentrations similar to those and Netter [3] clearly demonstrated that a coffee beverage de- in real coffee beverages are warranted to verify a structure- pleted in C5HTs was significantly less potent in inducing specific effect of coffee constituents, for example, N-MP and gastric lesions in rats compared to a corresponding, non- C5HTs, on mechanisms of gastric acid secretion. Apart from C5HT depleted coffee. Since the stomach-irritating potential the mechanistic approach, the clinical relevance of coffee and of C5HTs has been widely recognized, several technological its components N-MP, C5HTs, and CGAs stimulating gastric procedures have been developed to reduce C5HTs. For exam- acid secretion has to be clarified in future studies that involve ple, Kurzhals et al. [22] developed a solvent assisted extraction long-term interventions in study subjects with regular gastric of raw coffee beans, yielding a reduction of C5HTs of about acid output versus subjects with dyspepsia. 65%. Alternatively, mechanical dewaxing of raw coffee beans is used to eliminate C5HTs [23]. Furthermore, roasting con- This research project was supported by a grant from FEI ditions applied to the coffee beans affect the degradation of (Forschungskreis der Ernahrungsindustrie¨ e.V., Bonn, Ger- C5HTs, for example, convection roasting leads to a higher many) the AiF (Arbeitsgemeinschaft industrieller Forschung), the reduction of C5HTs compared to microwave treatment [24]. German Ministry of Economics (Project No. 14042 N) and Intense roasting is the main determinant of N-MP formation the German Academic Exchange Service (DAAD). The authors in the coffee bean [11]. Optimization of the roasting condi- thank Dr. C. L. Laboisse (Inserm 94–04, Faculte de Medicine, tions, taking into account the sensory profile of the resulting Nantes) for kindly providing the HGT-1 cells, clone 6.

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