Archive 2006 2007 2008 2009

Q: I see “sugar alcohol” listed on some food labels. What is this?

A: Also called polyols, sugar alcohols are reduced-calorie sweeteners used in many “diet” foods—from candies and jams to baked goods and ice cream—as well as in sugar-free gums, cough drops, mouthwashes, toothpastes, laxatives, and other products. Small amounts are found naturally in plant foods.

Though they resemble sugars and alcohol in chemical structure, sugar alcohols are actually carbohydrates that the body does not fully digest. Thus, they provide fewer calories (0.2 to 3.0 per gram) than sugar (4 per gram). They are not alcoholic. You can usually identify them by their “-ol” endings—as in sorbitol, xylitol, mannitol, maltitol, and erythritol, for example—though isomalt and hydrogenated starch hydrolysates are also sugar alcohols. Added sugar alcohols are always listed by name in the ingredients. If a product makes a “sugar-free” or “no sugar added” claim, however, sugar alcohols must be included in the Nutrition Facts panel, under Total Carbohydrate.

Because they are slowly and incompletely absorbed, sugar alcohols have less effect on blood sugar—so, in moderation, they are helpful for people with diabetes. They don’t promote cavities, either. And with fewer calories, sugar alcohols may help in weight control, though foods that contain them are not necessarily low-calorie (or healthful), and none are calorie-free.

A downside is that large amounts can cause gas, bloating, and diarrhea, since bacteria in the intestines ferment what is not absorbed. And you may inadvertently consume too much, since they are in so many products. Some, but not all, products carry a warning not to exceed a certain amount.

Q: Are knock knees a problem for exercise?

A: Yes, they can be. People who are very knock-kneed are at increased risk for a variety of injuries when running or doing other high-impact exercise. Many people are somewhat knock-kneed, and depending on the severity, this can put added strain on the hips, knees, lower legs, ankles, and feet. In runners, being knock-kneed can make their feet roll inward too much (overpronate). To see if you are knock-kneed, stand straight with your feet hip-width apart and look in a mirror: if your kneecaps seem to turn inward and are not aligned with the center of your feet, you have some degree of knock knee.

If you have knock knees (or, in contrast, are bowlegged) and are thinking about running or starting another high-impact activity, talk to a doctor or physical therapist. You may need orthotic devices for your shoes, or a special exercise program. You may have to avoid high-impact exercise altogether. Cycling, walking, and swimming are safer alternatives.

Q: Do certain foods cause hives?

A: Sometimes, but many other things can also cause them. Hives (the medical name is urticaria) are an allergic reaction causing red or skin-colored itchy welts that may last for several minutes or hours or even days.

Besides foods, hives may be triggered by medication, cosmetics, pollen, or animal dander. Less often, heat, cold, physical pressure, or sunlight may bring on an outbreak. Emotional stress or certain diseases may also trigger hives.

The remedy involves recognizing the trigger—if you can—and eliminating it. Think of recent changes in your life: a new food, drug, or cosmetic. Shellfish, strawberries, chocolate, tomatoes, eggs, wheat, dairy products, and nuts are some common culprits. If hives appear after you begin taking a new medication (penicillin is a classic trigger), let your doctor know right away. If your hives are accompanied by difficulty breathing or swallowing or by wheezing, get emergency medical care.

Q: How valid are home apnea tests?

A: They may be an option for some people. Sleep apnea is a common and potentially serious disorder in which a person stops breathing for short periods of time, possibly hundreds of times a night, and then chokes and gasps to recover. It can lead to daytime drowsiness, problems concentrating, and impaired driving, and is linked to hypertension, heart disease, and increased mortality.

The gold standard for diagnosing sleep apnea is polysomnography, a test done overnight at a sleep clinic that measures heart rhythm, airflow, blood oxygen levels, brain activity, and other variables while you sleep. But there can be a long wait for testing, or there may not be a facility near you.

According to the American Academy of Sleep Medicine (AASM), home monitoring devices can be an acceptable alternative for people with moderate to severe symptoms of apnea who don’t have other serious medical conditions (such as congestive heart failure or pulmonary disease) or other sleep conditions (such as insomnia or narcolepsy), which may affect the results. But you should be evaluated first by a doctor board-certified in sleep medicine, who can also guide you in the proper use of the device. Home monitors may also be useful for people who can’t go to a sleep lab, and for checking the progress of treatment.

Home monitors typically use a lightweight headset and/or nose, finger, or other sensors to record physiological changes during sleep, but they vary a lot in what they measure. The AASM advises that they should include at least three variables—airflow, respiratory effort, and blood oxygenation—and use sensors like those in sleep labs.

No matter which device you use, the results must still be interpreted by the sleep specialist. And if the test says you’re okay but your symptoms persist, you will need full testing at a sleep clinic.

UC Berkeley Wellness Letter, March 2009