ID 1115 -
Katechiny z zielonej herbaty
PL: Katechiny z zielonej herbaty
EN: Catechins – Green tea (camellia sinensis)
Pdf: Camellia sinensis
Oświadczenie (2)
- metabolizm glukozy
- glukozy we krwi
1. Charakterystyka żywności / składnika
The food/constituents that are the subjects of the health claims are Camellia sinensis (L.) Kuntze, catechins present in green tea, epigallo-catechin-3-gallate (EGCG) and green tea extract rich in EGCG.
The plant Camellia sinensis (L.) Kuntze is an evergreen shrub of the Theaceae family. Tea is an extract of the dried leaves from Camellia sinensis (L.) Kuntze and it is usually prepared by infusing the leaves in hot water. The composition of the tea leaves depends on a variety of factors, including climate, season, horticultural practices, and the type and age of the plant. Many kinds of tea are produced, which can be classified into three major types according to the different degrees of fermentation: green (un-fermented), oolong (semi-fermented) and black (fully fermented) (Wang et al., 2000).
The composition of tea beverages greatly depends on the type of leaves used, on the degree of fermentation and on the methods of preparation (Kaszkin et al., 2004; Astill et al., 2001). The degree of fermentation, the production process and the method of preparing the tea infusion have not been described in relation to the claims.
Green tea contains polyphenolic compounds, which include flavanols, flavandiols, flavonoids and phenolic acids. Most of the polyphenols in green tea are catechins. Epigallo-catechin-3-gallate (EGCG) is the most abundant catechin in green tea. In black teas, the most abundant polyphenols are tannins, mainly theaflavin and thearubigin (Mukhtar and Ahmad, 2000). Tea extracts/infusions also contain variable amounts of potentially active food constituents, such as caffeine, theanine or theogallin.
Green tea catechins (including EGCG) can be measured in foods by established methods.
The Panel considers that whereas Camellia sinensis (L.) Kuntze (tea) is not sufficiently characterised in relation to the claimed effects, catechins from green tea (including EGCG) are sufficiently characterised.
2.3. Utrzymanie prawidłowego stężenia glukozy we krwi (ID 1115, 1545)
The claimed effects are “glucose metabolism” and “blood glucose levels”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effects refer to the maintenance of normal blood glucose concentrations.
The Panel considers that long-term maintenance of normal blood glucose concentrations is a beneficial physiological effect.
3.3. Utrzymanie prawidłowego stężenia glukozy we krwi (ID 1115, 1545)
A total of 46 publications were cited in relation to the claimed effect. Some of the references referred to animal and in vitro studies, or provided details about the metabolism and pharmacokinetics of catechins, whilst others reported on the association between dietary catechins and disease risk or disease prevention (e.g. type II diabetes, cardiovascular disease, liver disease, atherosclerosis and cancer) in observational (cohort) studies. Other references were reviews dealing with dietary sources of polyphenols and health-promoting properties of green tea unrelated to glucose metabolism. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claimed effect.
Only five of the human studies provided examined the effect of catechins from green tea on blood glucose. However, three of the studies (Fukino et al., 2005, 2008; Hosoda et al., 2003) included insulin-dependent or non-insulin dependent diabetic subjects on either insulin or oral anti-diabetic therapy. The Panel considers that the evidence provided in these studies does not predict the occurrence of an effect of GTCs on the long-term maintenance of normal blood glucose concentrations in the general population. Also, one of the studies investigated the effect of GTCs on post-prandial glycaemic and insulinaemic responses (Tsuneki et al., 2004). The Panel considers that no conclusions can be drawn from these measures in relation to the long-term maintenance of normal blood glucose concentrations.
In the study by Ryu et al. (2006), 55 type II diabetic patients (24 women) who were not regular tea consumers drank 900 mL of water containing 9 g of green tea daily and 900 mL of water alone for four weeks each following a randomised, cross-over design. The Panel notes that whilst it is not stated whether subjects were taking blood glucose lowering medications or not, an exclusion criterion was uncontrolled diabetes. The Panel also notes that green tea was not sufficiently characterised regarding its catechin content, and that fasting blood glucose concentrations are not a reliable marker of long- term blood glucose control. The Panel considers that no conclusions can be drawn from this study for the scientific substantiation of the claimed effect.
The Panel concludes that a cause and effect relationship has not been established between the consumption of catechins (including EGCG) from green tea (Camellia sinensis (L.) Kuntze) and the long-term maintenance of normal blood glucose concentrations.
Warunki i możliwe ograniczenia stosowania oświadczenia
Recommended dosage 400-600mg
Catechins are active and functional polyphenol components of green tea leaves.
One cup (200ml) of brewed green tea may contain 100-150 mg of catechins.or equivalent of 50-60mg of EGCG.
The usual consumption of green tea is about 5-10 cups per day, which is equivalent to 500-1200 mg of catechins or 250-600 mg of EGCG per day.