Acid and the Reheated Cup of Coffee: Stomach Can Handle It
Dear Dr. Roach: My wife continually tells me that I should not drink reheated coffee because it concentrates the acid in coffee and is bad for me. I never drink more than one cup per day, and I always use a non-dairy creamer and Splenda. I have researched this question online and several responses say it is not harmful. In the meantime, she drinks orange juice every day, which has a lower pH than coffee. She sometimes complains about acid indigestion. Your comments? — A.
Answer: Acid is measured by the pH scale — with the lower the number, the more acid in the liquid. Coffee has a pH of about 5, slightly acidic, whereas orange juice has a pH of 3, which means it is a hundred times more acidic. Reheating coffee should not change the acid concentration.
Your stomach has a pH of about 1.5 — much more acid than either juice or coffee. The caffeine in coffee can stimulate your stomach to make more acid, and can weaken the sphincter muscle that keeps the stomach acid from going up into the esophagus. However, if it isn’t bothering you, there is no reason to stop drinking coffee.
One cup of juice usually doesn’t cause acid indigestion either.
Dear Dr. Roach: I am 81 years old and in excellent health. My blood pressure is low, and I drink several glasses of water a day. I get my kidneys checked by my doctor every three months. The last results of my GFR have been 62, 67, 66 and 58. I am very concerned because the last count went down. My doctor isn’t worried and tells me to drink water and exercise. Should I change my diet? Should I see a kidney specialist?— E.M.
Answer: GFR — glomerular filtration rate — is a test of kidney function. It usually is calculated based on age, sex and blood creatinine level. The normal value for a healthy 30-year-old is above 90.
GFR decreases with age. The expected level for an 81-year-old would be 59-63, which is right about the range you’re in. Creatinine levels may vary a bit from day to day, and I would not be surprised if the next reading is higher.
I agree with your doctor that this isn’t something to worry about and that changing your diet is not necessary. I would not recommend a kidney specialist unless your GFR drops persistently.
Dear Dr. Roach: I take the statin drug atorvastatin since my heart surgery. The sticker on the bottle reads, “Do not eat grapefruit or drink grapefruit juice at any time while taking this medicine.” My cardiologist said this warning was based on rather thin clinical trials, and it was OK to continue eating one grapefruit in the morning and taking the statin at bedtime. Are there new developments on this topic?
Answer: Grapefruit juice indeed can affect the metabolism of atorvastatin (Lipitor) and many other medications. However, the amount of grapefruit needed in order to have a significant effect is quite high -- the manufacturer recommends avoiding consumption of more than a quart (1.2 liters) of grapefruit juice a day.
I agree with your cardiologist that a grapefruit is a healthy way to begin the day and is not likely to cause any problems with atorvastatin.
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 or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Health newsletters may be ordered from www.rbmamall.com.