Alex Shvartsman wrote -- Unfortunately some thinks are not practical in today's society.  Have you ever breast fed a baby 3-4 times an hour all day long?  As is my baby eats on demand which is pretty often 

--- Alex, it's great that your wife feeds the baby on demand yet she might want to try and leave the baby on the breast for much longer... many babies come off the breast after a few minutes  but will continue after a short break if not taken off... 
I used to keep my kids on for half an hour or longer on the breast this way... 

<snip> <<wearing the baby around all the time is just not practical>>
--- don't see why she has to 'wear' the baby all the time?... why not keep him in the cot in between feeds and just be around... the longer the baby feeds the longer the breaks between feeds will become... I know sometimes we can feel like a milking machine etc.and it could be a bit of a downer particularly when very tired... it's important your wife gets enough sleep too... if the baby has a period of time within a 24 hours cycle in which he sleeps for a few hours she should go to sleep at that time too as interupted sleep is not as good an longer un-interrupted sleep... might help with milk production too...

<<I understand spinach is another food to avoid for a while due to the oxalic acid which binds calcium. I wonder when a safe "Time" is to introduce these foods?>>

Alex, you son is only 4 months old and you already worry too much :-)
good luck,

Dedy