Tamarind and raw mango too...
http://www.geocities.com/isebindia/2000/00-01-05.html
read this paragraph specifically:
Traditionally, tamarind is consumed in one form or the other by the people all over India. In South India, tamarind is used throughout the year in the form of various preparations like Curry, ‘Sambhar’, ‘Rasam’, and ‘Chutney’. In North India, especially in summer, Tamarind water blended with ‘jeera’ or other spices are taken as ‘Golguppa’ or as ‘chutney’. Raw mango drinks, barley water with lemon or tamarind or black carrot preparations in the form of cold drinks are also widely used in summer. Many of us, perhaps, are not aware of the health protective role played by these foodstuffs in summer. Scientific investigations have shown that tamarind and raw mango contain some proteins and glycolipids that bind with fluoride and thus protect us from fluoride poisoning. Traditionally, the source of our drinking water is mainly from wells and ponds. It is now well known that well water is rich in fluoride content, particularly in Southern parts of India, it is very high. However in north India, when the water level of the wells goes down in summer, fluoride content in the water goes high. Consumption of tamarind or raw mango has been shown to protect us from fluoride poisoning. This fact was discovered after an incident of heavy fluoride poisoning in a place in south Andhra Pradesh, sometime in late 1980s. The people of this region, sometime in early 1980s, found the cultivation of tomato more lucrative and began to use tomato as a substitute for tamarind and in due course tamarind was altogether eliminated from their food. The result was disastrous. An unidentified serious disease - some neurotic problems afflicted almost the entire population of the region and many became paralysed. It became so serious that the doctors and medical authorities were very much perplexed. After detailed investigations, it was finally discovered that this abnormal disease was due to heavy fluoride poisoning. The people of the region were taking drinking water from wells from time immemorial. Then how comes suddenly this problem arose? Indeed high fluoride content in well water is found in almost all other regions of South India, but the people of these regions were not facing any such fluoride poisoning. The search finally led to the discovery that the elimination of tamarind from the food caused fluoride poisoning. Research carried out on tamarind further established that certain proteins and glycolipids found in tamarind bind with fluoride and thus protect us from fluoride poisoning. Tamarind also contains certain compounds that lend protection from solar radiation and protect us from the damages caused by the free radicals and super oxides.