Dear Dr. Roach: I am 57 years old and love Pepsi, Coke and unsweetened iced tea for the caffeine, which greatly improves my mood and gives me more energy. Unfortunately, I am borderline diabetic and get horrible kidney stones. I need a caffeine replacement source.

Drinking more water does not do the trick. I gag trying to drink coffee. I have no interest in gas-station energy drinks or shots. Chocolate has too much sugar. Anything with sucralose or artificial sweeteners leaves a horrible aftertaste. I’ve gone months without caffeine, and I feel rundown. Are there any natural supplements or foods that might help me? The difference of being with and without caffeine is very noticeable for me. — M.D.

Answer: I’m guessing you have calcium oxalate stones (the most common type) and that you have been warned because tea has oxalate in it. However, there are two competing factors in tea: One is the fluid, which is very good for people who want to avoid stones, while the other is oxalate, which you don’t want.

It turns out that drinking tea reduces the overall risk of kidney stones. However, the stronger the tea, the more oxalate, so you do want to drink tea that hasn’t been steeped for too long. Furthermore, green tea has less oxalate than oolong or black, so this would be a preferred choice for you. Of course, I recommend unsweetened tea for everyone but especially for a person who is diabetic or prediabetic.

There are other options. It’s not hard to find caffeinated water now, and there are also caffeine tablets for people who really need it. The amount of caffeine in tea is much less than in coffee, on the order of 30-50 mg per cup of green tea and 40-70 mg in black tea, compared to 100 mg in coffee on average. (Specialty coffees can be much higher when brewed.) Caffeine tablets are typically 100-200 mg and might be a lot more than you need or want.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu.