Jeg vet ikke om alle siterer til denne artikkelen når dere sier at proteiner eliminerer effekten av grønn te (eller mer bestemt EGCG katekinet). Denne artikkelen (linken over) refererer til en studie (1) hvor forsøkspersonene inntok enten en såkalt høyproteindiett (100-120g Protein/d) eller en diett med lavere proteininnhold (50-60g Protein/d). Resultatene gruppene imellom ble omtrent like etter endt studie.
Jeg synes det virker litt rart å konkludere med at timingen av grønn te inntak har noe å si for fettforbrenningen og slikt, siden studien ikke sier noe om dette, den forteller jo egentlig bare hvor mye protein man kan innta ila dagen før de gode effektene av grønn te og proteiner utligner hverandre. En annen ting det ikke står noe om i utdraget (kunne tenkt meg å se hele studien) er om gruppen som hadde et høyt inntak av proteiner konsumerte dette i tillegg til en fast diett som motparten hadde, isåfall ble det jo inntatt flere kcalorier fra den siden, og det kan være grunnen til at effekten av grønn te forsvinner (Dette er bare synsing folkens).
I artikkelen det ble linket til påstås det at effekten av katekinene forsvinner når man legger til melk i en kopp med te, men jeg vet ihvertfall om en studie som sier at kroppen klarer å ta opp katekinene bedre med 50% melk tilsatt grønn te.. (2)
Har også lest et par tråder om at den kommersielle grønne teen (f.eks fra lipton eller twinings) ikke er "ekte" grønn te, og ikke inneholder like mye EGCG som de "ekte" grønne tebladene man får hos innvandrersjapper f.eks. Er dette tilfellet?
Sist: Har det noen hensikt å drikke grønn te mtp. fettforbrenning? Prøvde meg på pubmed, men skjønte ikke mye av siden.. hehe
Man kan regne med at en pose grønn te kjøpt fra et supermarked (i referert studie er det kjøpt i the U.K.) inneholder mellom 51,5 - 84,3 mg katekiner pr gram tørt materiale (3). På en 2grams tepose vil det si ca 103 - 168,8 mg.
Angående fettforbrenning så orker jeg ikke legge inn studier om det her, kan heller gjøre det dersom du er spesielt interesset. Dog kan det virke som om inntak av grønn te øker fettmobilisering under trening. Du kan søke på de to studiene under i Pubmed om du ønsker det.
(Effect of endurance training supplemented with green tea extract on substrate metabolism during exercise in humans.)
(Green tea catechin consumption enhances exercise-induced abdominal fat loss in overweight and obese adults.)
Am J Clin Nutr. 2009 Mar;89(3):822-30. Epub 2009 Jan 28.
1) Green tea catechin plus caffeine supplementation to a high-protein diet has no additional effect on body weight maintenance after weight loss.Abstract
BACKGROUND: Green tea (epigallocatechin gallate + caffeine) and protein each were shown to improve body weight maintenance after weight loss. OBJECTIVE: We investigated the effect of a green tea-caffeine mixture added to a high-protein (HP) diet on weight maintenance (WM) after body weight loss in moderately obese subjects. DESIGN: A randomized, placebo-controlled, double-blind parallel trial was conducted in 80 overweight and moderately obese subjects [age (mean +/- SD): 44 +/- 2 y; body mass index (BMI; in kg/m(2)): 29.6 +/- 2.0] matched for sex, age, BMI, height, body mass, and with a habitually low caffeine intake. A very-low-energy diet intervention during 4 wk was followed by 3 mo of WM; during the WM period, the subjects received a green tea-caffeine mixture (270 mg epigallocatechin gallate + 150 mg caffeine/d) or placebo, both in addition to an adequate protein (AP) diet (50-60 g protein/d) or an HP diet (100-120 g protein/d). RESULTS: Subjects lost 7.0 +/- 1.6 kg, or 8.2 +/- 2.0%, body weight (P < 0.001). During the WM phase, WM, resting energy expenditure, and fat-free mass (FFM) increased relatively in both the HP groups and in the AP + green tea-caffeine mixture group (P < 0.05), whereas respiratory quotient and body fat mass decreased, all compared with the AP + placebo group. Satiety increased only in both HP groups (P < 0.05). The green tea-caffeine mixture was only effective with the AP diet. CONCLUSION: The green tea-caffeine mixture, as well as the HP diet, improved WM independently through thermogenesis, fat oxidation, sparing FFM, and, for the HP diet, satiety; a possible synergistic effect failed to appear.
Mol Nutr Food Res. 2007 Sep;51(9):1152-62.
2) Common tea formulations modulate in vitro digestive recovery of green tea catechins.Green RJ, Murphy AS, Schulz B, Watkins BA, Ferruzzi MG.
Department of Food Science, Purdue University, West Lafayette, IN 47907, USA.
Abstract
Epidemiological evidence suggests a role for tea catechins in reduction of chronic disease risk. However, stability of catechins under digestive conditions is poorly understood. The objective of this study was to characterize the effect of common food additives on digestive recovery of tea catechins. Green tea water extracts were formulated in beverages providing 4.5, 18, 23, and 3.5 mg per 100 mL epicatechin (EC), epigallocatechin (EGC), epigallocatechin-gallate (EGCG), and epicatechin-gallate (ECG), respectively. Common commercial beverage additives; citric acid (CA), BHT, EDTA, ascorbic acid (AA), milk (bovine, soy, and rice), and citrus juice (orange, grapefruit, lemon, and lime) were formulated into finished tea beverages at incremental dosages. Samples were then subjected to in vitro digestion simulating gastric and small intestinal conditions with pre- and post-digestion catechin profiles assessed by HPLC. Catechin stability in green tea was poor with <20% total catechins remaining post-digestion. EGC and EGCG were most sensitive with less, not double equals 10% recovery.
Teas formulated with 50% bovine, soy, and rice milk increased total catechin recovery significantly to 52, 55, and 69% respectively. Including 30 mg AA in 250 mL of tea beverage significantly (p<0.05) increased catechin recovery of EGC, EGCG, EC, and ECG to 74, 54, 82, and 45% respectively. Juice preparation resulted in the highest recovery of any formulation for EGC (81-98%), EGCG (56-76%), EC (86-95%), and ECG (30-55%). These data provide evidence that tea consumption practices and formulation factors likely impact catechin digestive recovery and may result in diverse physiological profiles.
J Agric Food Chem. 2002 Jan 30;50(3):565-70.
3) Total phenol, catechin, and caffeine contents of teas commonly consumed in the United kingdom.Abstract
Levels of total phenol, catechins, and caffeine in teas commonly consumed in the United Kingdom have been determined using reversed phase high-performance liquid chromatography. Tea bags or tea leaves were purchased from local supermarkets and extracted in boiling water for 5 min. The resulting data showed considerable variability in both total phenols [80.5-134.9 mg/g of dry matter (DM) in black teas and 87-106.2 mg/g of DM in green teas] and
catechins (5.6-47.5, 51.5-84.3, and 8.5-13.9 mg/g of DM in black, green, and fruit teas, respectively); this was most probably a result of differing agronomic conditions, leaf age, and storage during and after transport, as well as the degree of fermentation. Caffeine contents of black teas (22-28 mg/g of DM) were significantly higher than in less fermented green teas (11-20 mg/g of DM). The relative concentration of the five major tea catechins ranked EGCG > ECG > EC > EGC > C. The estimated U.K. dietary intakes of total tea catechins, calculated on the basis of an average tea consumption of three cups of tea (200 mL cup, 1% tea leaves w/v), were 61.5, 92.7, and 405.5 mg/day from fruit teas, black teas, and green teas, respectively. The coefficients of variation were 19.4, 88.6, and 17.3%, respectively, indicating the wide variation in these intakes. The calculated caffeine intake ranged between 92 and 146 mg/day. In addition, many individuals will consume much larger quantities of tea, of various strengths (as determined by the brewing conditions employed). This broad spread of U.K. daily intakes further emphasizes the need for additional research to relate intake and effect in various population groups.