Mothers who eat more salmon before giving birth boost levels of a vital nutrient in their breast milk, but could lower levels of disease-fighting antibodies they pass on while feeding their baby, researchers have found.
Long-chain omega-3 fatty acids, found in oily fish such as salmon, are crucial during early childhood when they are needed for optimal growth and development. They help the growth of a baby's brain and eyes, and may also help the development of healthy blood vessels, heart, and immune system.
As a result, pregnant women are encouraged to eat one or two servings a week of certain kinds of oily fish known to provide high levels of omega-3.
However, very little is known about the influence of eating oily fish during pregnancy on the omega-3 fatty acid content of the mother's milk, and on immune substances, such as the antibodies passed from mother to baby during breastfeeding.
The protection against infection that this provides to vulnerable newborns is one of the reasons why breastfeeding is strongly recommended by health professionals in the first months after birth.
A European consortium of researchers, led by the University of Southampton and the University of Reading, collaboratively conducted a dietary intervention study in which pregnant women were randomly assigned to eat their normal diet, or one high in salmon.
Researchers found that those mothers that had eaten salmon during the latter stages of their pregnancy increased the amount of omega-3 fatty acids in milk during the first month after birth.
But it also lowered levels of secretory immunoglobulin-A (sIgA) - an important antibody that helps protect the newborn against infection.