How to lower an elevated GGT

I have went for some blood work and was told i had an elevated GGT, and told to refrain from alcohol for 4-6 weeks, on the:
22/3/10 ggt was 179     alt/sgpt 84
3/6/10 ggt         107      alt/sgpt 63
23/6/10 ggt        77       alt/sgpt 39
26/7/10 ggt        84       alt/sgpt 52

The last result is the one which i was annoyed with because it has spiked this is still being alcohol free,  i am a smoker about 15-20 per day would drink coffee 2 cups per day was told coffee should be ok and help to lower, also 2 litres of water per day i have recently 13/9/10 had an upper abdomen ultrasound which covered liver, kidneys, spleen and pancreas. no gallstones were seen either.  would you have any ideas on how i can lower my GGT. all my ultrasound tests were normal

Thanks
Julian.