If you are a nursing mother, think twice before freezing or refrigerating your expressed breast milk as you could be undermining its crucial antioxidant content. It seems that freezing or refrigerating breast milk significantly reduces the amount of antioxidant present in it. Even so, researchers say that frozen breast milk still has more antioxidants than fresh formula milk.

You can read about this study in Archives of Disease in Childhood.

Thomas Hegyi, co-author of this new report, said \"We find fresh breast milk contains more antioxidants than refrigerated breast milk or frozen breast milk or formula.\" Hegyi works at the Robert Wood Johnson Medical School, New Jersey, USA.

Antioxidants are vital for a baby’s immune system to fight off infection. Antioxidants mop up the free radicals in our bodies, free radicals damage us.

Expressing and refrigerating breast milk has become much more common as more women return to work soon after giving birth. Expressing the milk and storing it in the refrigerator has also become more popular as it allows fathers to bottle feed their babies.

Hegyi added, \"Nothing should change based on this study. People who have to refrigerate their breast milk, people who have to freeze their breast milk because they have to in order to go to work, should continue to do what they are doing.\"

The researchers examined breast milk samples from 16 mothers within 24 hours of delivery. Each sample was divided for five tests: fresh; after being stored for two days at 4 C; after being stored for 7 days at 4 C; after being stored two days at -20 C; and after being stored seven days at -20 C. They also tested formula samples.

Fresh breast milk had the highest antioxidant capacity - 1.66, on the researchers’ scale. Next was breast milk that had been refrigerated for two days (1.58), followed by breast milk that had been refrigerated for a week (1.48), frozen for two days (1.45) and frozen for a week (1.34).

The formula milk, when fresh, had an antioxidant capacity of 1.07. The number went down slightly after freezing and refrigerating.