I don't think it is quite as the dietician said.  The amount of
lactose in the milk is relatively constant.  What we *think* is going
on is that if the baby is drinking mostly low fat milk, this results
in rapid gastric emptying, with a large amount of lactose being
presented to the small gut at one time, too much for the lactase in
the brush border to handle.  Thus the baby gets signs of lactose
intolerance.  But he is *not* lactose intolerance.  This is a problem
of poor feeding advice (10, 15, 20 minutes on each side).

see: Woolridge MW, Fisher C. Colic, "overfeeding", and symptoms of
lactose malabsorption in the breastfed baby: a possible artifact of
feed management? Lancet 1988;August 13;382-4

Jack Newman, MD, FRCPC