Archive 2005 2006 2007 2008

Q: Can taking fish oil capsules help treat psoriasis?

A: Possibly, though research is limited and inconsistent. Psoriasis symptoms come and go on their own, so it’s difficult to evaluate the effects of dietary changes.

People with this skin disorder produce an excess of inflammatory substances. Because the omega-3 fats in fish oils have anti-inflammatory effects, it’s reasonable to think they would help.

But studies—most of them old, small, and of varying quality—have had mixed results. A British study in 1988 of 28 people with psoriasis, for example, found that high doses of fish oil significantly reduced redness, itching, and scaling. In a much larger study in the New England Journal of Medicine in 1993, however, fish oil supplements were no better than corn oil (used as a placebo). Other studies have noted that fish oil may enhance some treatments and reduce adverse side effects of certain drugs used for psoriasis.

Even if fish oil is useful, it’s not known how much you should take to treat psoriasis—and the large amounts used in studies can be dangerous (by inhibiting blood clotting, for instance) in some people. There’s no harm in eating more oily fish, but if you want to try high-dose fish oil supplements, talk to your doctor first.

About “psoriasis diets”: All kinds of diets are promoted for psoriasis, including low-calorie, vegetarian, and gluten-free. Some research has suggested that antioxidants (as in fruits, carrots, and tomatoes), as well as vitamin D, may be beneficial. But while certain diets may help some people, there’s no good evidence that diet overall plays a significant role in psoriasis.

Q: Is it a problem if one of my legs is shorter than the other?

A: Only if it is causing pain or discomfort. Most of us have legs of slightly different lengths, and this causes no problem. But for some people this difference contributes to hip, back, knee, or foot pain, especially if they begin an exercise program. Legs of unequal length can distort posture and thus affect the ability to withstand impact when running or walking. The pain can occur on the side of the longer or shorter leg.

The difference in leg length can be anatomical—caused by genetics or, for instance, a leg fracture. Or it may be functional—the legs are the same length but, for example, the feet hit the ground differently (most often one foot rolls slightly inward), so that one leg is effectively “shorter.” If your pelvis is asymmetrical, or you have a muscle imbalance on one side, or you’ve had a total hip replacement, it may seem that one leg is shorter.

It is nearly impossible to measure your own legs accurately. The best way is with X-rays, but this is rarely necessary. It’s usually sufficient for a physician, podiatrist, or physical therapist to observe your gait carefully and use a tape measure to measure your legs. One problem: some practitioners overemphasize the importance of small differences in leg length and/or mismeasure legs, leading to inappropriate treatments.

If you have an anatomical difference in leg length that is causing hip, back, knee, foot, or back pain, inexpensive shoe lifts or custom-made orthotic devices may help. If it’s a functional problem, stretching and strengthening exercises may be recommended.

Q: What is natto, and does it have health benefits? What about natto supplements?

A: Natto is a fermented soybean food. Part of traditional Japanese cuisine, it’s commonly added to rice, miso soup, and sushi, and has a strong cheese-like flavor.

Natto is rich in vitamin K, made by bacteria during fermentation, as well as isoflavones (plant estrogens). It supplies fiber, protein, unsaturated fat, iron, calcium, potassium, and other nutrients, and is low in sodium.

Preliminary research, mostly from Japan, supports some possible health benefits. A study in the Journal of Nutrition in 2006, for example, linked natto intake to increased bone mineral density at the hip in postmenopausal women. Another Japanese study, in 2004, linked natto (and other soy foods) to reduced risk of prostate cancer, possibly due to its isoflavones. A study in the British Journal of Medicine that same year, however, linked fermented foods—though not natto specifically—to increased prostate cancer risk.

Natto contains an anti-clotting enzyme, nattokinase, which is sold as a dietary supplement for heart protection. But its safety and effectiveness have not been adequately tested in people. While perhaps promising, it is not a proven substitute for aspirin or prescribed blood thinners. Supplements vary, and what the best dose would be is unknown. Anyone who has a bleeding disorder or is on medication that affects blood clotting, such as warfarin (brand name Coumadin), should avoid this supplement.

Q: How dangerous is snuff?

A: Unlike cigarettes, snuff does not cause lung cancer, but it does promote mouth and nasal cancers and gum disease, and may, like cigarettes, increase the risk of heart disease and other health problems.

Snuff, which is powdered or ground tobacco, comes dry (for nasal use) or moist (placed in the mouth). Sales of moist snuff have more than doubled in the U.S. in the last 20 years, while cigarettes, chewing tobacco, and dry snuff have become less popular. “No smoking” signs may encourage snuff use. Users are typically young men, including many athletes.

While the chemicals in tobacco smoke are absorbed through the lungs, those in snuff are absorbed through the lining of the nose or mouth and through the intestinal tract. The resulting blood concentrations of nicotine are just as high, and the addictive effect is perhaps even greater.

A related form of moist snuff called snus, popular in Sweden, has been in the news lately because it is being test-marketed in the U.S. by major tobacco companies. (Swedish snus is already sold on the Internet.) The small pouches of tobacco, often flavored, are inserted behind the upper lip; no chewing or spitting is required. Snus contains lower levels of certain carcinogens than other moist snuff, but the levels are still high, and it’s unclear how much safer it is. For instance, studies have linked it to pancreatic and gastrointestinal cancers.

Marketers as well as some anti-smoking experts claim that snuff—especially snus—can help people quit cigarettes. But, more likely, it may get young people hooked on nicotine and serve as a gateway to smoking. There are much safer ways to replace nicotine when quitting smoking, such as nicotine gum and patches.

UC Berkeley Wellness Letter, May 2008