Our analytical results showed a higher variability of the composition of sage teas than what we actually had expected. For example, the content of rosmarinic acid varied by more than a factor of 20 between the lowest and highest brands of sage tea. This shows that it is important to analyze a comprehensive number of samples rather than single samples as it has been done in previous studies (Aoshima et al., 2007
; Hossain et al., 2011
). The difference in polyphenols content is also evidenced by the corresponding antioxidative potential, which varied from 0.4 to 1.8
mL. The information on the packages did not provide details about the plant origins or the exact composition, making it difficult for us to explain the (possible) factors leading to these differences. The brands with the highest ORAC and FC index (samples 6 and 7) were labeled to be hand-collected shoot apex material from organic farming (sample 6) or sage tea selected from shoot apex material (sample 7). This could explain the difference between these two samples and the other tea samples, which appear mainly to be composed of leaf material. Previous research on FC index, thujone and camphor (Walch et al., 2011
) has reported results from several batches of a single manufacturer, which were very consistent. For example, the FC index for five different batches of shoot apex material (corresponding to sample 6 in this study) was 14.9
0.3. Similar to the results in this study for polyphenols, ORAC, and FC index, the variations for thujone and camphor were significantly higher between manufacturers than within a single brand. This indirect evidence points to sage variety and chemotype, cultivation conditions, climate, or processing conditions (especially during drying) as explanations for the differences rather than pure inter-batch variations.
It is interesting to note that sage tea not only is available as an herbal medicinal product but is also sold as a food product in many supermarkets, as it may simply be consumed as a “pleasant drink” for culinary purposes (Dweck, 2000
; British Herbal Compendium, 2006
). There was no distinct difference between the teas marketed as medicine (samples 1–13) and those marketed as food (samples 14–16). In contrast, the brands with the lowest ORAC (samples 4, 5, and 8) were all marketed as medicine, whereas the food teas showed an average composition.
Our results confirm that it may be worthwhile to explore sage as a food ingredient not only for its flavor profile but also for its antioxidant capacity so that it may be a substitute for the synthetic antioxidants that are commonly applied in foods (Madsen and Bertelsen, 1995
According to Wang et al. (1998
), the compounds in sage with the highest antioxidant capacity were found to be rosmarinic acid and luteolin-7-O
-β-glucopyranoside, of which rosmarinic acid quantitatively dominated in our samples.
As mentioned in the introduction, there are no legal specifications regarding these compounds in sage tea, which may be an explanation for the obvious lack of quality awareness in this regard. From a consumer’s perspective, it is surely a mandatory demand that medicines contain the active principles in a defined amount. In the case of sage (as for many other traditional herbal medicines), the active principle is not known. However, at least the main components that have a hypothesized effect, such as polyphenols or antioxidants, should be regulated. In their Salvia officinalis
monograph, the EMA – the regulatory authority in Europe – justified an acceptable daily intake (ADI) of thujone at 5.0
mg/person for a maximum duration of use of 2
weeks (European Medicines Agency, 2009
). Lately, the EMA has reconsidered this ADI in a public statement (European Medicines Agency, 2011
). Nonetheless, if the regulatory authority holds the opinion that a certain risk seems to be involved in the usage of sage as medicine, it is difficult to understand why minimum requirements of the possibly beneficiary compounds, have not yet been established. In times when the public is discussing the financing of healthcare and the quality and the benefits of medicines have to be evaluated, it seems important for the credibility of herbal medicines to establish specifications. Therefore, a dose–benefit assessment appears to be necessary, which could be followed by minimum requirements of the active principles. The FC index appears to be useful as a screening parameter for sage tea quality, as it is highly correlated with rosmarinic acid and easier to determine with less instrumental effort than the ORAC value or the specific compounds using HPLC.