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Evaluation of Oxidative Stress in Biological Samples Using the Thiobarbituric Acid Reactive Substances Assay
Published on: May 12, 2020
Determination of oxidative status in breast and formula milk
D Turoli1, G Testolin, R Zanini
1Department of Food Science and Microbiology, Division of Human Nutrition, University of Milan, Milan
Insights
Stored breast milk and some infant formulas can be sources of pro-oxidants for newborns. Lipid peroxidation products were higher in human milk, especially when stored, indicating potential oxidative stress risks.
Area of Science:
- Neonatal nutrition
- Oxidative stress in infants
- Food chemistry
Background:
- Infant nutrition relies on breast milk and formula.
- Oxidative stress is a concern for newborn health.
- Understanding milk's oxidative potential is crucial.
Purpose of the Study:
- To assess the pro-oxidant potential of formula milk and stored breast milk.
- To compare oxidation parameters in different milk types and storage conditions.
Main Methods:
- Assessed total antioxidant capacity and lipid peroxidation products (lipid peroxides, TBARS, conjugated dienes).
- Analyzed fresh and stored (at -20°C) human milk (HM) and various infant formula (FM) brands.
Main Results:
- Formula milk brands showed significant variations in oxidation parameters.
- Lipid peroxidation products were higher in HM than FM; stored HM had much higher lipid peroxides.
- No significant difference in mean total antioxidant capacity between HM and FM.
Conclusions:
- Significant lipid peroxide formation occurred in stored HM, likely due to enzymatic activity.
- Fresh HM exhibited higher lipid peroxidation products than FM, possibly due to sample handling and light exposure.
- High lipid peroxide levels in milk may be natural, with HM susceptible to peroxidation post-expression.
Aim:
To investigate to what extent formula milk and stored breast milk, commonly used in hospitals, could be pro-oxidant sources for newborn babies.
Methods:
We determined total antioxidant capacity and lipid peroxidation products, such as lipid peroxides, TBARS and conjugated dienes, in fresh and stored (at -20 degrees C) samples of breast milk and in different brands of formula milk.
Results:
There were notable differences in the oxidation parameters in several brands of formula milk, particularly concerning the levels of lipid peroxides and total antioxidant capacity. No difference was found in the mean total antioxidant capacity between formula and breast milk, even if the vitamin content is much higher in formula milk than in breast milk. On the contrary, all the considered lipid peroxidation products were higher in human milk (HM) than formula milk (FM), and lipid peroxides were much higher in HM stored at -20 degrees C. Many differences were found between different formula milks.
Conclusion:
There was a conspicuous formation of lipid peroxides in HM stored at -20 degrees C, which was probably caused by an increased presence of free fatty acids due to lipoprotein lipase activity during storage. Unexpectedly, even fresh HM had a higher concentration of lipid peroxidation products when compared to FM. This could be ascribed to the higher susceptibility of HM to degradation during analysis because of manipulation and light exposure. However, it is also interesting that the high content of lipid peroxides did not correspond to a low total antioxidant capacity in either breast or formula milk. This could signify that such levels of lipid peroxidation products might be present naturally in milk and HM after expression is subject to a strong peroxidation either at room temperature or at -20 degrees C.
