DEAR DR. ROACH: I have heard for a while now that the black stuff on burnt toast is carcinogenic. I don’t eat it because it tastes bad, but now I hear that any browning on things like bread and potatoes could cause cancer. What is the evidence for these claims, and what do you recommend we do to address them in our daily lives? -- P.N.
ANSWER: The Food Standards Agency in the U.K. recently issued a warning against browning high-starch foods, such as potatoes and toast, as browning can cause a chemical reaction that turns amino acids in food into acrylamide. The more browned starches are, the more acrylamide is produced (boiling or microwaving does not produce acrylamide).
The agency estimated the amount of acrylamide that increased cancer risk in animal studies, and found that frequently eating food with acrylamide could come close to the amount that might increase cancer risk in humans. It has advised people to cook food until golden in color, but avoid a dark-brown or burnt color.
In my opinion, the risk probably is very low for most people. Toast and potatoes aren’t a great source of micronutrients anyway, and shouldn’t be a large proportion of calories in a healthy diet. People who do consume a lot of roasted potatoes and toast probably should make their diets a bit more diverse. Cooking to a lighter-brown color is prudent for people who consume these foods regularly, but occasional consumption of more-browned foods is probably safe.
DEAR DR. ROACH: I just had a full blood workup as part of my annual physical. I am 72 years young, and all tests came back smack dab in the middle of the upper and lower ranges. The exception was urobilinogen. This showed a range of 0.2-1; my test results were 2.0. The doctor said not to worry about it, but if it is not important, why was it tested? What does the result of 2.0 mean? -- C.E.D.
ANSWER: Urobilinogen is made by bacteria in the bowel from bilirubin, secreted by the liver in bile. A high level might indicate excess bilirubin production, such as is seen when blood is being broken down. It also can occur when the liver doesn’t reabsorb as much as it should, as in people with cirrhosis. Another reason might be excess production by intestinal bacteria, seen in some people with bacterial overgrowth or very slow bowel transit (especially those with constipation).
By itself, a modestly elevated urobilinogen level is nonspecific. If that were the only abnormality on your laboratory report, it would be very unlikely that you would have significant liver disease such as cirrhosis -- many laboratory findings likely would be abnormal. Similarly, blood breakdown, whether from a large hematoma (bruise) or from abnormal breakdown of large red cells, could cause a high urine bilirubin. My guess is that you are one of the 9 percent or so of people who have slightly high urobilinogen levels due to slightly slower digestion than normal.
I think your doctor was right that at this low level, it is unlikely to be something to worry about, but higher levels could be a clue toward serious disease.
READERS: The booklet on colon cancer provides useful information on the causes and cures of this common malady. Readers can obtain a copy by writing: