Dear Doctor: What are the benefits and risks of taking kava?

Dear Reader: The kava shrub originates from the South Pacific, where Pacific Islanders used it to promote psychological and physical relaxation for medicinal and ceremonial purposes. Within traditional cultures, the root of the plant is crushed, ground and then combined with a mixture of water and coconut milk to make it drinkable. In the naturopathic boom of the 1990s, kava was touted as a safe alternative to other medications used for anxiety. Today, kava is a popular supplement for anxiety, and various brands can be found in any health food store.

The root of the kava plant contains 18 different phytochemicals, or plant-based compounds, known as kavalactones. These compounds alter the conduction of nerve signals, decrease excitatory neurotransmitters, increase the ability of the amino acid GABA to bind its receptors, inhibit the enzyme monoamine oxidase, and reduce uptake of the neurotransmitters noradrenaline and dopamine. All of this is a technical way of saying: Kava can help reduce anxiety.

A 2003 review of 11 randomized controlled trials with a total of 645 patients assessed kava supplements' ability to treat anxiety. The studies used varying levels of the kavalactones, from 60 to 280 milligrams. These doses are significantly higher than what Pacific Islanders traditionally used. The studies varied from one to 25 weeks.

Ten of the 11 studies showed a decrease in anxiety compared with placebo. These benefits appeared to be comparable to the effect of tranquilizers such as benzodiazepines and the anxiety drug buspirone. Side effects included nausea, stomach aches, drowsiness and headaches. No liver toxicity was reported, but then, no liver tests were performed.

Note that kava has been banned in the United Kingdom and within Europe due to liver toxicity. More than 100 cases of liver toxicity related to the use of kava have been identified, some leading to liver transplant and others leading to death. There are many reasons for liver damage. For one, kava depletes glutathione, a chief antioxidant, within the liver. It also inhibits enzymes involved in the metabolism of many drugs. Many of the cases of liver toxicity were seen in people who had prior liver disease or used alcohol in addition to kava.

You may think kava is safe if you don't have liver disease or are not taking medications metabolized by the liver, but that might not be the case. A study of 31 people in Hawaii who were regular kava drinkers showed a significantly greater elevation of two liver enzymes compared with people who were not kava drinkers. There is some evidence that kava that is prepared with water is less harmful to the liver than suspensions prepared in acetone or ethanol.

Studies have shown that consumption of kava supplements leads to a slower reaction time and an impairment of motor skills. However, there has been no proof of any decline in cognitive function. Also, because it inhibits multiple enzymes and has psychoactive properties, kava likely should not be taken with anti-depressants.

In summary, kava may help relieve anxiety in the short term. However, due to the severe side effects at its current doses, I would be hesitant to use it for the short term and recommend not using it in the long-term. Cognitive behavioral therapy has greater long-lasting benefits.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Our family visits a lake in the mountains every summer where the water almost never gets above 60 degrees. I dislike swimming in cold water, but my husband and dad insist that it's good for you. It won't get me into the water, but I just want to know -- are they right?

Dear Reader: Some people find cold-water swimming invigorating. Others, like the groups who take part in those midwinter "polar bear plunges," love an even icier challenge. And then there are those of us who prefer not to suffer for our swim.

Swimming in and of itself is great exercise. Your heart, lungs and muscles all get a workout. The buoyancy of the water is kind to weight-bearing joints, and the concentration, isolation and repetition of swimming laps can be meditative. And while there are plenty of theories about how and why spending time in cold water is good for you -- it sure does feel fantastic once you get out -- when it comes to scientific evidence, things get a bit trickier.

Research into cold-water immersion tends to focus on its use as therapy for sports injuries. Some studies with individuals who do open-water ocean swimming cite a lower rate of respiratory illness, but that data is anecdotal. And while several studies have found an increase in white blood cells in individuals who take daily cold showers, whether the resulting boost in immune response translates into long-term better health remains an open question.

What's more apparent are the potential dangers of swimming in cold water. Water conducts heat far more efficiently than air. By some estimates, you lose heat 25 times more quickly in water than in air. That's why the body responds so differently to a walk in 60-degree weather and a swim in water at that same temperature. It's also why, when you get into water that's 60 degrees or colder, it causes a phenomenon known as "cold shock."

In cold shock, the body releases adrenaline and stress hormones, which can make you either feel exhilarated or panicky. In response to the sudden cold, you lose control of your breath. Your lungs contract and you gasp and breathe irregularly, a response that can last for up to a minute. To protect the vital organs, blood vessels contract, which raises blood pressure. As the body redirects blood flow away from the periphery and to your core, coordination can become impaired.

Because of this, experienced cold-water swimmers warn against jumping into icy water. Instead, they recommend that you dash water on your face, chest and shoulders to "warn" your nervous system of what's coming. Then wade in, steadily but slowly, until you're fully submerged. Monitor your breathing and heartbeat and, if all is well, off you go.

It's understandable that your dad and husband would want to make swimming an all-family affair. But whether to brave the chilly lake is a matter of personal preference.

If you -- or they -- have high blood pressure or any heart issues, don't do it. And if you are going to go the cold-water route (for just a few minutes or so the body will acclimate), have fun.

Just don't stay out too long. And never swim alone.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Because of the potential risks of proton pump inhibitors, should I have an H. pylori breath or stool test to make sure I have this bacterium before committing to long-term treatment with a PPI?

Dear Reader: That's an excellent question, and it reflects our increasing knowledge about both the bacterium and PPIs. First identified in 1982, Helicobacter pylori is a bacterium that causes chronic inflammation of the stomach lining and stomach, as well as duodenal ulcers; it can also lead to gastric cancer and a slow-growing type of cancer known as MALT lymphoma. In fact, H. pylori is the most common chronic bacterial infection in humans. As for PPIs, they can cause deficiencies in some nutrients and increase the risk of infection with the bacterium C. difficile.

Because these PPIs (Nexium, Prilosec, Prevacid, Aciphex, Protonix, Dexilant) decrease the acidity in the stomach, allowing for healing of inflamed tissues, they're used to treat inflammation in the stomach; ulcers of the stomach or the duodenum; and acid reflux.

Whether you should take PPIs long-term depends on your condition. In most cases for which the medication is prescribed long-term, you would have an endoscopy to visualize the esophagus, stomach and the duodenum (first portion of the small intestine). If the endoscopy found a stomach or duodenal ulcer, your gastroenterologist would have tested for H. pylori with a rapid urease test or with a biopsy test. So if you had an endoscopy that found an ulcer, you likely already have your answer.

If you didn't have an endoscopy and have been diagnosed with gastritis, then I would recommend checking for H. pylori. If you're infected, you could be treated with antibiotics instead of a long-term PPI. The breath test for H. pylori evaluates the bacterial infection's ability to break down urea, a chemical compound excreted in urine, and produce carbon dioxide. This is a very good test with an 88 to 95 percent sensitivity in picking up the organism, but the sensitivity decreases substantially if you are already taking a PPI.

One study in those taking the PPI Prevacid found the sensitivity of the urea breath test decreased by 33 percent. The stool test for H. pylori has a sensitivity of 94 percent in picking up the organism. It is also more cost-effective than the breath test. But again, if you are already taking a PPI or even Pepto-Bismol, the sensitivity significantly decreases.

If you're considering taking a PPI long-term for acid reflux (heartburn), there has been no proof that treating an H. pylori infection would improve the acid reflux unless you had an ulcer in the duodenum. Again, this is something that would be seen on endoscopy. Regarding acid reflux, you should first look at stopping cigarette smoking, alcohol, caffeine and chocolate before considering long-term use of a PPI.

In summary, if your doctor diagnoses you with gastritis, an H. pylori stool test would be of benefit. If your doctor suspects an ulcer, then I would recommend getting an endoscopy, during which you would be tested for H. pylori.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)