Medical Examiner

Your Health This Week

How to live 14 years longer. And LASIK, looking good.


This week, Dr. Sydney Spiesel discusses long-term results for LASIK surgery, the drawbacks of chewing stick after stick of sugarless gum, and how to live 14 years longer.  

LASIK outcomes

Question: Is laser eye surgery safe over the long term? And how well does it fix nearsightedness? I often wonder when I ride the subway and read the ads for all those eye surgeons.

Study: A recent study by a group of Spanish ophthalmologists, writing with Dr. Jorge Alió, looked at long-term outcomes for LASIK, a laser surgery method of eye correction introduced in Europe 18 years ago. The researchers evaluated long-term value and safety for almost 120 patients (196 eyes, in total) with severe myopia—so severe that under today’s guidelines they would no longer be eligible for the surgery. The researchers measured how good, stable, and safe the patients’ correction of vision was.

Findings: The majority of patients achieved very good correction soon after surgery, though another quarter of them needed a second course of surgery to achieve this level. Over the 10 years that followed, these results slowly regressed a bit for most of the participants, moving the group, on average, from perfect vision to a mild degree of nearsightedness. They ended up on average only about 15 percent as nearsighted as they were before surgery.

Complications: Remarkably, given that safety concerns are the reasons LASIK is no longer used for such severely nearsighted patients, only two eyes of two patients (1 percent) suffered the bad complication called corneal ectasia, in which the cornea loses strength as a result of the procedure and bulges, resulting in poor vision. A few other patients developed other visual problems over time. However, these were related not to the surgery but to the normal aging process, or to problems encountered in the extra-deep eyeballs of badly nearsighted people.

Conclusion: This method, then, seems to have been remarkably successful in improving the eyesight of some very hard-to-treat patients, and with rather less risk than I would have anticipated. This is very good news, indeed, especially since worldwide about 18 million LASIK procedures have been performed since the method was introduced.

Chewing gum and the runs

Problem: Chronic diarrhea without an obvious cause is a difficult condition for physicians to sort out. This distressing symptom, which can result in excessive weight loss, is sometimes caused by allergy; sometimes results from an acquired inability to digest a food ingredient (like milk sugar); and sometimes reflects a bacterial, viral, or parasitic infection. Now medical science has identified yet another cause: chewing gum.

Case study: Juergen Bauditz, writing with four colleagues from the Charité Medical University in Berlin, recently described two patients, a 21-year-old woman and a 46-year-old man, with diarrhea and a lot of weight loss over an eight-month to one-year period. They underwent an intensive but fruitless gastroenterologist’s evaluation (don’t ask!). And then the puzzled doctors returned to the patients to ask questions. This time, good history-taking identified the real culprit—too much sugarless chewing gum.

Explanation: Sugarless chewing gum contains a sweetener called sorbitol—a material often used as a commercial replacement for sugar and other sweeteners. Although it has calories, sorbitol is poorly absorbed by the body and doesn’t nourish the mouth bacteria that contribute to tooth decay, and so seems perfect for products like sugarless gum, diet drinks, and candy. But because it is absorbed poorly, it can concentrate in the bowel and block the normal process of water reabsorption in the large intestine (which enables stools to become solid). The resulting diarrhea can, in turn, interfere with the absorption of important nutrients, leading to weight loss and even malnutrition, a condition clearly present in one of the patients studied in Berlin.

Findings: The amount of sorbitol found in 16 sticks of gum chewed daily (which, actually, seems like a lot to me, though I’m not a gum-chewer) will cause diarrhea in about half of normal people. Both of the patients studied chewed more than that every day. The prescribed treatment (throwing away the sugarless gum) was successful for both of them: Their diarrhea resolved and their normal weight was restored.

Also: How much of the money initially spent on expensive testing could have been saved had the right questions about diet been asked at the beginning? (Granted, my question is not exactly fair—as I am fond of saying, in the cold light of the retrospectoscope, everything is clear.) The authors of the study don’t tell us, but there is other research that hints at the answer. Twenty years ago, some Danish gastroenterologists studied patients who secretly abused laxatives, which caused chronic diarrhea. The work-up for those patients must have been comparable to that for the gum-chewers. At that time, the cost of medical care and testing came to more than $3,500 a patient. Surely today the cost would be several times that. Modern medicine has tended to devalue asking questions of patients in favor of elaborate laboratory tests, endoscopies, and biopsies. Perhaps it is time to rethink that balance.

Lifestyle and longevity

Question: What are the factors that really could make your life longer and healthier? Every day we are barraged with a huge assortment of confusing and often contradictory medical advice. So, I’m pleased to report some simple advice that is likely to yield reasonable dividends in good health. Keep this checklist, and you can throw out the rest.

Study: A new paper (authors here) describes the relationship between lifestyle and mortality for about 20,000 middle-aged and elderly men and women living in Norfolk, a fairly rural part of England not far from London. The participants all began in generally good health and were closely tracked for 10 years. (The British National Health Service made illnesses easy to follow.) The study started with a detailed health and lifestyle questionnaire about significant medical history, smoking, alcohol use, and level of physical activity, reflecting both the demands of employment and recreational pleasures. The subjects’ consumption of fruit and vegetables was estimated by blood tests for vitamin C, which for all practical purposes comes only from plant foods.

Scoring: The scoring was as simple as could be. A participant could collect from zero to four points. Not smoking netted one point. Five or more servings of fruit and vegetables a day (based on the measured vitamin C level) was worth another point. Some alcohol consumption, but not a lot, added another point. And finally, some physical activity, either at work or at play, added one more. A teetotaling smoker who works at an office desk and eats meat and potatoes instead of oranges while watching television—a low score of zero points. A cricket-playing nonsmoker who drinks five half-pints of Guinness a week and eats lots of apples and broccoli—a high score of four points.

Conclusion: What’s the difference between zero and four? An astonishing fourfold difference in the likelihood of dying at a given age. This means that the four-point cricket player has the same likelihood of dying as a zero-point smoker who is 14 years younger. People who score in the one-, two-, and three-point range are at intermediate mortality risk, directly proportional to their scores.

Question: What we don’t know is whether this is a prescriptive formula: that is, if the smoking, fruit-eschewing, teetotaling couch potato can change his or her risk level by a change of habits or of lifestyle. I hope and suspect so, but honestly, we have no idea. Next study, please. In the meantime, these four simple choices seem awfully attractive.