Archive 2005 2006 2007 2008

Q: When you discuss coffee, you seldom mention decaf. Does decaf have the same benefits and risks as regular?

A: Decaf and regular coffee share many effects, since they share more than 1,000 naturally occurring compounds. Many of these are potentially healthful, including a variety of antioxidants. Others are potentially harmful, such as substances that cause heartburn in some people.

Most research has focused on caffeine or caffeinated coffee. Over the years coffee (sometimes including decaf) has been blamed for causing everything from high blood pressure to bone loss, but it has been cleared of nearly all health charges.

Decaf obviously does not have the drawbacks of caffeine: It won’t cause jitters, insomnia, or increased heart rate, nor will it possibly increase the risk of miscarriage. But decaf also does not have caffeine’s benefits: it won’t improve reaction time, mental acuity, alertness, and mood or ward off drowsiness.

Some recent research indicating that coffee may actually help prevent certain disorders has focused only on regular coffee. For instance, studies linking coffee to reduced risk of gallstone disease suggests that caffeine is the key element. In contrast, studies on Type 2 diabetes have found that decaf also has a potential benefit. Most research on possible protection against Parkinson’s or Alzheimer’s disease has included only regular coffee.

Over the years decaf has been the focus of several health scares that have not panned out. For instance, there have been concerns about some methods used to remove caffeine from coffee, but these have turned out to be unwarranted.

Q: Are self-tanning lotions safe?

A: Their active ingredient, dihydroxyacetone (DHA), has been approved by the FDA for use in cosmetic products, which means it’s considered safe when used as directed. DHA, itself colorless, reacts with cells in the top skin layer, causing them to darken and give the appearance of a tan. As the skin sloughs off, the color fades. Self-tanning (also called “sunless tanning”) products are available as creams, gels, and sprays, including spray applications at spas.

Allergic reactions are uncommon, but little is known about long-term effects. A few years ago a European study in Mutation Research found that DHA caused genetic damage in human skin cells. More recently, a German animal study found that DHA significantly boosted free radical formation in skin cells exposed to the sun, which, in theory, may increase the risk of skin cancer. Still, the American Academy of Dermatology recommends sunless tanning as a safe alternative to sunbathing and tanning beds.

It’s not known whether there are any health risks from inhaling or ingesting the chemical, so be sure to use spray tanners in well-ventilated areas and keep your eyes and mouth shut tightly until the mist settles. When applying cream, be careful not to get any in your eyes, nose, or mouth.

Self-tanning products shouldn’t give you a false sense of security. Most do not contain sunscreen, and if they do you must still reapply a regular sunscreen every few hours. Interestingly, DHA provides some sun protection itself—about SPF 3—but you need SPF of at least 15.

Q: Is Greek yogurt different nutritionally from regular yogurt?

A: Traditional Greek yogurt, made from sheep or cow’s milk, is strained to remove much of the whey (liquid), which makes it thicker than regular yogurt. It doesn’t need the pectin or other thickeners found in many yogurts. Some Greek yogurt is imported, but domestic “Greek-style” yogurts are increasingly available.

Greek yogurt has about 50% more protein than regular yogurt: 20 vs. 13 grams per 8 ounces in nonfat versions (all numbers here are averages). And it’s lower in carbohydrates and thus lactose, the milk sugar that some people have trouble digesting. (Most lactose-sensitive people find that yogurts in general are easier to digest than other dairy foods.) Greek yogurt tends to have less calcium than regular yogurt—150 to 200 milligrams vs. 300 to 450 milligrams per 8 ounces—but it is still a good source.

Compared to regular whole yogurt, whole Greek yogurt has significantly more fat (20 vs. 7 grams per 8 ounces) and more calories (280 vs. 140), so be sure to select nonfat (120 calories) or lower-fat versions (130 to 150 calories). Because they are all thick and creamy, you may not notice the difference.

Plain Greek yogurt is classically paired with honey and nuts or used to make tzatziki (a yogurt and cucumber sauce). It’s a good substitute for sour cream on top of a baked potato. And because there’s less whey, it stays fresh longer and is less likely to separate or curdle when heated. You can make something like Greek-style yogurt by straining plain yogurt through a cheesecloth or coffee filter for a couple of hours, stirring occasionally. Further straining will produce even thicker “yogurt cheese.”

Q: Is inversion therapy good for my back?

A: It might make you feel better temporarily, but it won’t cure a back problem—and there are risks. Inversion therapy involves lying at a downward slant or hanging upside down, using gravity boots, yoga slings, or special tables or chairs.

The idea is that being in an inverted position allows the natural pull of gravity to decompress and elongate the spine, thereby relieving pressure on disks, ligaments, and nerves—and, presumably, pain. Small studies, most dating back to the 1980s and earlier, indicate that inversion therapy increases the space between vertebrae and may improve low-back symptoms (or at least decrease the number of sick days due to back pain) and lumbar scoliosis (curvature of the lower spine). But the effects are temporary at best—and it could even worsen back pain afterwards in some cases.

Moreover, inversion therapy can have serious side effects, such as increased blood pressure, bleeding into the retina, headaches, and blurred vision. It should be avoided by people with hiatal hernias, eye disorders, heart and circulatory problems, osteoporosis, high blood pressure, ear infections, and spinal injuries, as well as pregnant women, people who are very overweight, and those taking certain medications.

Bottom line: We do not recommend inversion therapy. If you have back pain, consult a professional skilled in back care. There are other treatments and exercises that may help in the long term. If you still want to try it, talk to your doctor first.

UC Berkeley Wellness Letter, April 2008