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A forced titration study of the antioxidant and immunomodulatory effects of Ambrotose AO supplement

Stephen P Myers12*, Lesley Stevenson15, Phillip A Cheras12, Joan O'Connor12, Lyndon Brooks23, Margaret Rolfe3, Paul Conellan14 and Carol Morris4

Author Affiliations

1 Australian Centre for Complementary Medicine Education and Research, A Joint Venture of the University of Queensland and Southern Cross University, Lismore, Australia

2 NatMed-Research Unit, Research Cluster for Health and Wellbeing, Southern Cross University, Lismore, Australia

3 Graduate Research College, Southern Cross University, Lismore, Australia

4 Centre for Phytochemistry and Pharmacology, Southern Cross University, Lismore, Australia

5 The New Zealand Institute for Plant and Food Research Limited, Auckland, New Zealand

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BMC Complementary and Alternative Medicine 2010, 10:16  doi:10.1186/1472-6882-10-16

Published: 30 April 2010



Oxidative stress plays a role in acute and chronic inflammatory disease and antioxidant supplementation has demonstrated beneficial effects in the treatment of these conditions. This study was designed to determine the optimal dose of an antioxidant supplement in healthy volunteers to inform a Phase 3 clinical trial.


The study was designed as a combined Phase 1 and 2 open label, forced titration dose response study in healthy volunteers (n = 21) to determine both acute safety and efficacy. Participants received a dietary supplement in a forced titration over five weeks commencing with a no treatment baseline through 1, 2, 4 and 8 capsules. The primary outcome measurement was ex vivo changes in serum oxygen radical absorbance capacity (ORAC). The secondary outcome measures were undertaken as an exploratory investigation of immune function.


A significant increase in antioxidant activity (serum ORAC) was observed between baseline (no capsules) and the highest dose of 8 capsules per day (p = 0.040) representing a change of 36.6%. A quadratic function for dose levels was fitted in order to estimate a dose response curve for estimating the optimal dose. The quadratic component of the curve was significant (p = 0.047), with predicted serum ORAC scores increasing from the zero dose to a maximum at a predicted dose of 4.7 capsules per day and decreasing for higher doses. Among the secondary outcome measures, a significant dose effect was observed on phagocytosis of granulocytes, and a significant increase was also observed on Cox 2 expression.


This study suggests that Ambrotose AO® capsules appear to be safe and most effective at a dosage of 4 capsules/day. It is important that this study is not over interpreted; it aimed to find an optimal dose to assess the dietary supplement using a more rigorous clinical trial design. The study achieved this aim and demonstrated that the dietary supplement has the potential to increase antioxidant activity. The most significant limitation of this study was that it was open label Phase 1/Phase 2 trial and is subject to potential bias that is reduced with the use of randomization and blinding. To confirm the benefits of this dietary supplement these effects now need to be demonstrated in a Phase 3 randomised controlled trial (RCT).

Trial Registration

Australian and New Zealand Clinical Trials Register: ACTRN12605000258651