Abstract
Background: Cancer chemo- and radiotherapy are constantly associated with unwanted side effects at least partially ascribable to oxidative stress, an imbalance between pro-oxidant and antioxidant factors. However, the possible indication and efficacy of antioxidant supplementations – including glutathione-based formulas – aimed to restore the oxidative balance should be, respectively, evaluated and monitored carefully with reliable analytical tools. Aim: Because previous studies on cystic fibrosis and athletes showed that high-cysteine-content, whey-based formulas were able to improve glutathione levels in cystic fibrosis and in healthy exercising people, the aim of this preliminary study was to evaluate the impact on oxidative balance of a new antioxidant supplementation, based on a high-cysteine formula containing a protein mimicking breast milk, on women conventionally treated for breast cancer. Subjects and methods: Twenty women suffering from breast cancer under ambulatory conventional antineoplastic treatment were supplemented for 12 consecutive months with 10 g u.i.d. of an oral nutraceutical lipid- and lactose-free formula containing a mix of peptides from cow's milk whey having a high content of cysteine and glutamic acid as the main biochemical precursor of glutathione (Prother®, DMF Limbiate, MI, Italy). During the study period the recruited subjects underwent a periodical (bimonthly) clinical visit, during which they were tested for oxidative balance (BAP test and d-ROMs). Before and at the end of the study the women were invited to complete the Spitzer Questionnaire. Results: Plasma antioxidant capacity, as detected by the BAP test, showed a marked early trend towards a progressive increase, reaching statistical significance at the end of the treatment (2319.5 ± 288.7 vs. 1894.5 ± 362.5 μmol/l reduced iron, respectively; p = 0.007). Plasma oxidant status, as measured by means of the d-ROMs test, after an irregular time-course, increased significantly at the 12th month, compared to the baseline value (350.29 ± 39.29 vs. 407.00 ± 58.54 CARR U, respectively; p = 0.0017). The treatment was well tolerated. Discussion: The breast milk-mimicking protein formula intake was associated with a restoration of biological antioxidant potential, maybe by increasing the bioavailability of antioxidant components, and reduced glutathione, with no apparent interference with the intrinsic pharmacological/chemical mechanism (oxidant species generation) of the current treatment (chemo/radiotherapy). Conclusions: This preliminary study indicates that 12 months of regular oral intake of a high-content cysteine nutraceutic formula is associated with increased plasma antioxidant capacity in women conventionally treated for breast cancer. Moreover, the data from oxidative status assessment suggest that the above supplement did not interfere with oxidant production, the increase of which is related to the cancer and antineoplastic treatment itself. Finally, the d-ROMs and BAP tests were shown to be very reliable tools to monitor ambulatory oxidative balance in this kind of patient.