I found this article, but I have a hard time believing it especially since it's backing up the claim with
Cold or iced drinks may interfere with digestion according to Chinese and Ayurvedic medicine.
http://www.healthy.net/scr/Article.asp?Id=608
4. Don't wash your food down.
Too much liquid with your meals may dilute the digestive juices you need. Try to drink liquid before your meals so you won't feel thirsty during the meal. Cold or iced drinks may interfere with digestion according to Chinese and Ayurvedic medicine. A little liquid with the meal may not interfere with digestion and a glass of warm water with lemon juice l/2 hour before a meal may promote secretion of hydrochloric acid.