A number of years ago, I had pain in my feet and I discovered, thanks to Dr. Hulda Clark 's books, that drinking black tea would likely be hard on the kidneys to eliminate the oxalic acid that it contains, and that "oxalic acid" would become like "crystals" deposit in the feet (like gout), and of course, would cause pain in the feet. Having read this in Dr. Clark's books, I immediately stopped drinking tea. Within a week, half of the pain was gone. Later, I used capsules of Cayenne Pepper (as suggested by Dr. Clark) to help blood circulation... and now, for a number of years I have had no pain in my feet. Because of my personal experience, and Dr. Clark's advice on black tea, I would not encourage people to drink black tea. However, I would like to know whether GREEN TEA would be better. Can anyone tell me whether GREEN TEA contains less oxalic acid than Black Tea ?