Tamara Bakuradze

Antioxidant‐rich coffee reduces DNA damage, elevates glutathione status and contributes to weight control: Results from an intervention study

Epidemiological and experimental evidence increasingly suggests coffee consumption to be correlated to prevention or delay of degenerative diseases connected with oxidative cellular stress. In an intervention study comprising 33 healthy volunteers, we examined DNA-protective and antioxidative effects exerted in vivo by daily ingestion of 750 mL of freshly brewed coffee rich in both green coffee bean constituents as well as roast products. The study design encompassed an initial 4 wk of wash-out, followed by 4 wk of coffee intake and 4 wk of second wash-out. At the start and after each study phase blood samples were taken to monitor biomarkers of oxidative stress response. In addition, body weight/composition and intake of energy/nutrients were recorded. In the coffee ingestion period, the primary endpoint, oxidative DNA damage as measured by the Comet assay (± FPG), was markedly reduced (p<0.001). Glutathione level (p<0.05) and GSR-activity (p<0.01) were elevated. Body weight (p<0.01)/body fat (p<0.05) and energy (p<0.001)/nutrient (p<0.001-0.05) intake were reduced. Our results allow to conclude that daily consumption of 3-4 cups of brew from a special Arabica coffee exerts health beneficial effects, as evidenced by reduced oxidative damage, body fat mass and energy/nutrient uptake.

Antioxidant effectiveness of coffee extracts and selected constituents in cell-free systems and human colon cell lines.

SCOPE Epidemiological studies suggest that coffee can reduce the risk of degenerative diseases such as diabetes type 2, cardiovascular disease and cancer. These beneficial effects have partly been attributed to the antioxidant activity of coffee. We determined composition and antioxidant potential of differentially roasted coffee extracts and investigated the impact of selected original constituents and roast products. METHODS AND RESULTS Parameters studied were direct antioxidant activity (trolox equivalent antioxidant capacity/oxygen radical absorbing capacity), cellular reactive oxygen species (ROS) level, DNA damage and protein expression of NAD(P)H: quinone oxidoreductase, γ-glutamylcysteine ligase and glutathione reductase in HT-29/Caco-2 cells at 24-h incubation. All extracts showed distinct direct antioxidant activity: medium roasts>light roast AB1 (caffeoylquinic acid (CQA)-rich Arabica Brazil extract); dark roast AB2 (N-methylpyridinium (NMP)-rich Arabica Brazil extract), and diminished t-butylhydroperoxide-induced ROS level in HT-29 cells (AB2>medium roasts>AB1). NAD(P)H:quinone oxidoreductase 1 expression and γ-glutamylcysteine ligase expression were distinctly induced by AB1 and 5-CQA, but not by AB2 and NMP. 5-CQA and caffeic acid exhibited highest trolox equivalent antioxidant capacity/oxygen radical absorbing capacity values (5-CQA: 1.3/3.5 mM and caffeic acid: 1.3/3.9 mM trolox); ROS level was distinctly diminished by 5-CQA (≥3 μM), catechol (30 μM) and trigonelline (≥30 μM), whereas menadione-induced DNA damage in Caco-2 cells was reduced by NMP compounds (1-30 μM). CONCLUSION The results emphasize that both original constituents and roast products contribute to the cellular antioxidant effectiveness of coffee.

Induction of antioxidative Nrf2 gene transcription by coffee in humans: depending on genotype?

The Nrf2/ARE pathway is a major cellular defense mechanism that prevents damage by reactive oxygen species through induction of antioxidative phase II enzymes. However, the activity of the Nrf2/ARE system is not uniform with variability in response presumed to be dependent on the Nrf2 genotype. We recently completed a pilot human coffee intervention trial with healthy humans, where large interindividual differences in the antioxidative response to the study coffee were examined. Here, we address the question whether differences in the modulation of Nrf2 gene transcription, assessed as an induction of Nrf2 gene transcription by Q-PCR, might be correlated with specific Nrf2 genotypes. To date, nine single nucleotide polymorphisms (SNPs) have been identified in the Nrf2 (NFE2L2) gene. Two of these, the −617C/A and −651G/A SNPs are located within the promoter region and have previously been reported to influence the activity of the Nrf2/ARE pathway by reducing Nrf2 transcriptional activity. Sequencing of the critical Nrf2 gene promoter region not only confirmed the existence of these SNPs within the participants of the trial at the expected frequency (33% carrying the −617C/A, 17% the −651G/A and 56% the −653A/G SNP) but also indicated reduced Nrf2 gene transcription associated with a normal diet if the SNPs at position −617, −651 or −653 were present. Of note, the data also indicated the study coffee increased Nrf2 gene transcription even in SNP carriers. This further highlights the relevance of genotype-dependent induction of Nrf2 gene transcription that appears to be largely influenced by dietary factors.

Coffee consumption rapidly reduces background DNA strand breaks in healthy humans: Results of a short‐term repeated uptake intervention study

SCOPE Intervention studies provide evidence that long-term coffee consumption correlates with reduced DNA background damage in healthy volunteers. Here, we report on short-term kinetics of this effect, showing a rapid onset after normal coffee intake. METHODS AND RESULTS In a short-term human intervention study, we determined the effects of coffee intake on DNA integrity during 8 h. Healthy male subjects ingested coffee in 200 mL aliquots every second hour up to a total volume of 800 mL. Blood samples were taken at baseline, immediately before the first coffee intake and subsequently every 2 h, prior to the respective coffee intake. DNA integrity was assayed by the comet assay. The results show a significant (p < 0.05) reduction of background DNA strand breaks already 2 h after the first coffee intake. Continued coffee intake was associated with further decrements in background DNA damage within the 8 h intervention (p < 0.01 and p < 0.001, respectively). Mean tail intensities (TIs%) decreased from 0.33 TI% (baseline, 0 h) to 0.22 TI% (within 8 h coffee consumption). CONCLUSION Repeated coffee consumption was associated with reduced background DNA strand breakage, clearly measurable as early as 2 h after first intake resulting in a cumulative overall reduction by about one-third of the baseline value.

Urinary Excretion of Niacin Metabolites in Humans After Coffee Consumption

Scope Coffee is a major natural source of niacin in the human diet, as it is formed during coffee roasting from the alkaloid trigonelline. The intention of our study was to monitor the urinary excretion of niacin metabolites after coffee consumption under controlled diet. Methods and results We performed a 4‐day human intervention study on the excretion of major niacin metabolites in the urine of volunteers after ingestion of 500 mL regular coffee containing 34.8 μmol nicotinic acid (NA) and 0.58 μmol nicotinamide (NAM). In addition to NA and NAM, the metabolites N 1‐methylnicotinamide (NMNAM), N 1‐methyl‐2‐pyridone‐5‐carboxamide (2‐Py), and nicotinuric acid (NUA) were identified and quantified in the collected urine samples by stable isotope dilution analysis (SIVA) using HPLC‐ESI‐MS/MS. Rapid urinary excretion was observed for the main metabolites (NA, NAM, NMNAM, and 2‐Py), with t max values within the first hour after ingestion. NUA appeared in traces even more rapidly. In sum, 972 nmol h−1 of NA, NAM, NMNAM, and 2‐Py were excreted within 12 h after coffee consumption, corresponding to 6% of the ingested NA and NAM. Conclusion The results indicate regular coffee consumption to be a source of niacin in human diet.

Abstract LB-249: Coffee drinking decreases background DNA strand breaks in humans: A randomized controlled trial

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Effects of coffee consumption on the level of spontaneous DNA strand breaks in peripheral white blood cells have not been reported yet. In this human intervention study the impact of consuming a dark roast coffee blend on the level of spontaneous DNA strand breaks was investigated. Healthy men (n=84) were randomized to consume daily for 4 weeks either 750 ml of fresh coffee brew or 750 ml of water, subsequent to a run in washout phase of 4 weeks. The study coffee was a blend providing substantial amounts of both, caffeoylquinic acids and the roast product N-methylpyridinium. Before and after the coffee/water phases, spontaneous strand breaks were determined by Comet assay. Both groups exhibited a similar level of spontaneous DNA strand breaks at baseline.In the intervention phase spontaneous ( background) DNA strand breaks slightly increased in the water only group, whereas they significantly decreased in the coffee group,leading to a 27 percent difference between both arms (p=0.0002). Food frequency questionnaires indicated no differences in the overall diet between groups, mean body weight during the intervention phases remaining stable. Consumption of the study coffee was found associated with a markedly lower level of pontaneous DNA strand breaks in white blood cells. Conclusion: Regular coffee consumption contributes to DNA integrity. Citation Format: Gerhard Eisenbrand, Tamara Bakuradze, Roman Lang, Thomas Hofmann, Dorothea Schipp, Jens Galan, Elke Richling. Coffee drinking decreases background DNA strand breaks in humans: A randomized controlled trial. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-249. doi:10.1158/1538-7445.AM2014-LB-249