Changes in markers of inflammation, antioxidant capacity and oxidative stress in smokers following consumption of milk, and milk supplemented with fruit and vegetable extracts and vitamin C

Abstract

Two milk-based beverages delivering twice the average daily antioxidant intake were formulated, based on synergistic combinations of fruit and vegetable extracts, and containing vitamin C (1.00 mg/ml) for shelf stability. Smokers (n = 42) consumed prototype milk A, B or non-supplemented milk (no extracts or vitamin C; 200 ml) twice daily for 6 weeks. Fasting and post-prandial (2 h after milk consumption) blood samples were collected at baseline and the end of each treatment. Non-supplemented milk significantly reduced fasting inflammatory cytokines (interleukin (IL) 6, IL-1β, tumour necrosis factor-α) compared to baseline. Both supplemented milk-based beverages significantly increased fasting plasma vitamin C concentrations and antioxidant potential and decreased serum uric acid, compared to non-supplemented milk. The beverages did not induce post-prandial oxidative stress or inflammation. Therefore, regular consumption of the supplemented milks may confer health benefits because of increased antioxidant potential or through mechanisms resulting from increased vitamin C or decreased uric acid concentrations.

Keywords::

• vitamin C
• uric acid
• inflammation
• synergy
• post-prandial

Acknowledgements

The authors would like to acknowledge Canterbury Health Laboratories for measuring urinary creatinine concentrations; Teresa Wegrzyn, Judie Farr and Claire Redman for their contribution in developing the prototype milks; and Angela Rowan and Nicholas Schnell (Fonterra Brands Ltd) for their assistance in interpreting the results.

Declaration of interest: This work was funded by the Foundation for Research, Science and Technology, New Zealand (Wellness Foods Programme, Contract C06X0405) and Fonterra Brands Ltd. Ms J. Todd has a conflict of interest because she is employed by Fonterra Brands Ltd, who partly funded the trial. This conflict is stated. The remaining authors do not have a conflict of interest.