The blood-brain barrier is not intact in infants until at least 6 weeks of life. This is why a newborn with a fever must be subjected to a spinal tap to rule out meningitis. Any virus or bacteria that a newborn is exposed to can go directly to the nervous system.

Now about diet, well until six weeks or in premature babies, there is only one diet..i.e. Milk. So i dont think it would play an important role in it.

However, it is also t he reason why the Hepatitis B vaccine at birth is so dangerous. Between 1991 and 1999, when the shot contained thimerisol, giving it at birth would have resulted in mercury crossing into the brain since the blood-brain barrier was not yet intact.

The normal timing of a blood-brain barrier forming is not more readily known.
I think this normal delay in the forming of a blood-brain barrier is an important piece of the puzzle and one of the reasons for the surge of autism in the 90's.

have them google it, they will get many sites.

Do you know where the Nurse who stated this got her info? My family who are nurse's asked me this?