negril - the guidelines have nothing to do with Europe! Who told you that? The UK (and US, and Canadian, and Australian, and yes, European, and everywhere else) guidance comes from studies carried out worldwide. In he UK, SACN, the Scientific Advisory Committee on Nutrition, was charged with examining this evidence and concluded that the UK should adopt the same framework.
www.sacn.gov.uk/meetings/sub_groups/maternal_child_nutrition/index.html
There are World Health Organisation guidelines, which are on the web, but if anyone wants to check out the sysematic reviews behind the guidance I suggest going to the Cochrane database, looking at the work of Kramer and Kakuma. The 'question' they researched was 'optimal duration of exclusive breastfeeding', and the conclusions are, in the main, based on the immunological factors in breastmilk, and the fact that there is no nutritional deficit in introducing solids after six months - an important question, because babies who are protected, immunologically, by excl bf for 6 mths have to be shown to grow well, too. It's no good just checking for health; you have to check for growth, too.
Jacwac, I don't understand why people who are clearly used to using the internet say they cannot find the research on this...I agree, you need more than statements if you want to look for the reasons, but this stuff is not hard to find!