A quick follow-up to last Friday's post, Breastfed Babies Avoid Allergies.
In that post I reported on research that said that breastfeeding a baby for the first six months reduced the chance of later allergies.
However, an article, Breast Is best, but watch out for the allergies by Matt Kaplan in the August 5, 2006 issue of New Scientist adds an unusual caveat.
Researchers at the Helsinki Skin and Allergy Hospital in Finland have been conducting a twenty-year-long study of mothers who breastfed their babies as long as possible. The children were assessed for allergies at ages 5, 11 and 20.
Exclusive breastfeeding for nine months or more actually appeared to increase the chances of a baby developing allergic conditions such as eczema and food hypersensitivity. At age 5, 56 per cent of children with a family history of allergy who had been breastfed for nine months or more had allergic symptoms, compared with 20 per cent of those who had been breastfed for between two and six months.
The researchers noticed that children who developed allergies after prolonged exclusive breastfeeding were most likely to do so during the first years of life, suggesting that environmental factors such as pollen exposure, diet and disease are the more important factors in the onset of allergies in later childhood and early adulthood.
"A beautiful hypothesis is that there is a time window when the immune system needs to be exposed to external antigens for it to develop properly," says team member Maria Pesonen, although more research is needed to be sure.
Until more research is done, mothers may want to think about stopping exclusive breastfeeding at about the seventh month and start introducing solid foods.