Dr. Roach: Is ‘really low’ urine pH a health hazard?

Dr. Roach
To Your Health

Dear Dr. Roach: I have a friend who’s 28 with “really low” urine pH (I don’t know how low). Apparently, it is due to constant dehydration and drinking coffee all day long, to the point that the doctor recommended that he drink lots of water with lemon (perhaps just to prevent dehydration and nothing else.)

That sounds counterintuitive to me. I recall you mentioning before that the body maintains a fairly constant pH. Does that also apply to urine? Could you please comment on urine pH, its spontaneous changes, causes and potential issues that acidic urine may cause in otherwise healthy males?


Dear K.S.: The body maintains a very constant pH of the blood at a slightly alkaline 7.4 (7 is neutral; below 7 is acidic, above 7 is alkaline). Even a few tenths of a point higher or lower and the body is in severe trouble, as enzymes stop working properly.

The primary method the body uses to regulate blood pH is by increasing or decreasing carbonic acid loss through breathing out more or less carbon dioxide, but the kidneys play their part by adjusting urine pH. Most North Americans consume a diet high in meat, which requires the kidney to excrete acid, but the urine pH cannot get much below 4.5 due to limitations of the kidney.

It is counterintuitive that consuming lemon juice, which is a quite strong acid (with a pH between 2 and 3), will cause the urine to become less acidic. This is because citric acid (which makes lemons “tart,” i.e., acidic) is metabolized to bicarbonate, which is alkaline and excreted in the urine. Nephrologists use this effect therapeutically in people with calcium oxalate stones.

If your friend has normal kidneys, a change in diet away from meat and with more plants will make the urine pH less acidic.

That said, there are a host of unusual causes of urine pH changes. The ones making the urine pH acidic are quite uncommon, and they include Cushing’s syndrome (excess cortisone) and excess licorice ingestion. Yes, really. Licorice contains glycyrrhizic acid, which acts like a hormone on the kidney to affect urine pH. Coffee has no consistent effect on urine pH, but dehydration can make urine more acidic. Because of the body’s immense capacity to maintain blood pH, however, it is unlikely your friend will develop medical issues due to low urine pH.

Dear Dr. Roach: Do chromium or biotin have a role in treating Type 2 diabetes?


Dear N.F.E: There was a great deal of enthusiasm for chromium picolinate a few years ago, and there is still evidence that the combination of chromium and biotin may decrease insulin resistance in people with Type 2 diabetes. Recent studies have suggested that these may improve glucose control, although the improvement was small, about 5% in a two-hour glucose tolerance test.

By themselves, they are not likely to dramatically improve control in people with Type 2 diabetes, particularly if they are not well controlled. However, it may be enough to tip the balance in some people. I am not yet ready to recommend it generally, despite a good safety profile.

Readers may email questions to ToYourGoodHealth@med.cornell.edu.