Dear Doctor: It seems like you can't go a day without probiotics turning out to be the cure for some ailment or another. Now we're being told they help depression. How can that be?

Dear Reader: We agree with you that probiotics are in the news quite a bit these days, and sometimes with more than a bit of hyperbole. Much of the news comes from legitimate scientific research now being done into the fascinating world of the gut biome. Having read many of the resulting papers, we can assure you that the researchers themselves are far more temperate and restrained in their findings than some headline writers, who seem to love the idea of a medical miracle.

Probiotics are live micro-organisms that are ingested for their health benefits. Found in yogurt, kefir and other fermented foods, as well as in dietary supplements, they live in our digestive tracts, particularly in the gut. There, they are believed to enhance immune function and inhibit the growth of pathogens.

The spate of recent news reports drawing a link between probiotics and depression relief are likely coming from the results of a study published last spring in the journal Gastroenterology. Researchers in Canada followed 44 adults with irritable bowel syndrome, or IBS, a bowel disorder. IBS causes abdominal pain and diarrhea or constipation, and there is evidence that probiotics can ease some of those symptoms. The subjects in this study also suffered from mild or moderate anxiety and depression, which can be common among people with IBS.

Half of the people in the study were given a certain strain of probiotic, and the other half received a placebo. At the six-week mark of the study, 64 percent of the patients taking the probiotic saw a decrease in test scores that rate depression. The placebo group's depression scores dropped half that amount, or 32 percent. Interestingly, the rate of anxiety in both groups remained the same. A final evaluation at the end of the 10-week study yielded the same results.

If you're wondering whether the depression lessened because the probiotic group felt better physically, you're not alone. But researchers also performed brain scans on the test subjects. The results of those scans led them to conclude that the probiotic reduced depression by changing brain activation patterns, specifically in the limbic system, which is the collection of structures in the brain associated with emotion and memory.

This research follows on the heels of a handful of other studies in recent years that suggest probiotics can alleviate the symptoms of depression. The thinking is this occurs because probiotics reduce gut inflammation, while simultaneously raising serotonin levels. There's even a great name for this emerging area of study -- the gut-brain axis. Communication goes both ways -- from gut to brain and from brain to gut -- via the nervous system, glands and hormones, and the immune system.

Thus far, studies into probiotics and depression have been small and brief, involving limited strains of probiotics. As researchers create larger, well-controlled and long-term studies that investigate multiple probiotic strains, the results should be fascinating.

(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: News coverage of a study recently suggested that frequent, moderate drinking could ward off Type 2 diabetes. Could this be true?

Dear Reader: You're right to distrust alcohol. Excessive use can increase the risk of multiple cancers as well as cirrhosis of the liver, nerve damage both peripherally and within the brain, weakened heart muscle and abnormal heart rhythms. It also can lead to traffic deaths and an addiction that destroys lives. However, small to moderate alcohol consumption has been shown to decrease the rate of heart attacks -- and also may help control blood sugar.

A recent Danish study analyzed 2007 and 2008 survey data on alcohol consumption from 28,704 men and 41,847 women. Survey participants were separated into different groups: no history of alcohol consumption; prior consumption but none in the last year; less than one day of alcohol consumption per week; one to two days of alcohol consumption per week; three to four days of alcohol consumption per week; and five to seven days of alcohol consumption per week.

After almost five years, the data showed that lifetime abstainers had a higher rate of Type 2 diabetes than other groups. The lowest rate was seen among those who drank alcohol three to four days per week. In fact, compared to people who consumed alcohol less than once per week, those men were 27 percent less likely to develop diabetes, and the women were 32 percent less likely to develop diabetes.

But before you take another sip of wine, let us parse the data a little. In the study, female abstainers were twice as likely to be obese when compared to women who drank alcohol three to four days per week or five to seven days per week. In men, this rate was about 50 percent greater. Similarly, male and female abstainers were twice as likely to be physically inactive when compared to the frequent alcohol users. Moreover, abstainers had a greater family history of diabetes and were more likely to be less educated. (The authors said they adjusted for these factors and, to some degree, they did.)

A 2012 European study found similar results. After controlling for the fact that people who consumed no alcohol were more likely to be inactive, obese and less educated, the authors showed that women who drank 1 unit of alcohol per day were slightly less likely to develop diabetes compared to women who drank 1 unit every two to eight days. For men, the connection between alcohol consumption and lowered diabetes risk was considered less significant.

Lastly, an analysis of 20 studies in 2009 showed that, in men, the protective benefit of alcohol was greatest at 22 grams of alcohol (about 1 1/2 glasses of wine) per day. In women, 24 grams of alcohol per day was most protective. But the authors didn't adjust their findings based on weight, physical activity or educational level.

Note that the European studies analyzed populations in which consumers of alcohol had generally higher rates of physical activity, which reduces the risk of diabetes; that may not hold true in the United States. But in summary, alcohol consumption -- though it has a myriad of problems -- does seem to be linked to a slight decrease in the risk of diabetes.

(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: My husband was recently hospitalized for pneumonia "of undetermined origin" and treated with IV antibiotics. Does that mean they don't know whether it was viral or bacterial? Are antibiotics used for both? I'm also worried that he might have a relapse.

Dear Reader: The word "pneumonia" refers to inflammation of the lungs, specifically the small air sacs, called alveoli, which sit in clusters at the far edges of the bronchial tree. These air sacs provide the surface area for the oxygen that you inhale to move from the lungs into the bloodstream and throughout the body.

When the air sacs become inflamed, they fill with fluid. People with pneumonia can often hear a crackling sound deep within their lungs as they draw a breath. The presence of that fluid not only makes it hard to breathe, it also prevents adequate oxygen from getting to all parts of the body. Additional symptoms include high fever, cough and chills.

Most often, pneumonia occurs due to some type of infection. The agent can be viral, as in influenza, or bacterial, as with Staph or Strep. More rarely the cause can be fungi, or chemical agents. Pneumonia can affect one or both lungs, and can be asymptomatic, which means you don't even realize you have it. That's commonly referred to as "walking pneumonia."

Differentiating between a virus and a bacterium as the cause of pneumonia can be a challenge. We go by a review of each patient's vital signs and symptoms, the results of chest X-rays, nasal swabs to look for flu viruses and sputum cultures to check the secretions in the lungs. Then we weigh all the evidence to arrive at the best determination.

Since your husband was treated with IV antibiotics, it means that his care team concluded the cause of his pneumonia was bacterial. Antibiotics are not used to treat viral pneumonia. Instead, the approach is supportive care -- rest, fluids, nutrition and time.

When we treat bacterial pneumonia, we don't always find the specific bug that's the cause. If we're lucky, we can pinpoint it through a blood culture or sputum sample. But in many cases, we choose the antibiotic we think will be most effective and monitor its progress.

More than 900,000 people in the United States become ill with pneumococcal pneumonia each year, which is the most common type of bacterial pneumonia. To help combat the Streptococcus (pneumococcus) bacteria, the American Lung Association recommends that children younger than 5 and adults over 65 receive a pneumococcal vaccination series.

Pneumonia in and of itself isn't contagious. However, as with a cold or the flu, a cough or sneeze by someone with pneumonia can spread the organisms that caused it. If your husband is feeling better after the course of antibiotics is complete, then they have done their work.

Should he relapse, which is known as recurrent pneumonia, his care team will likely want to evaluate further. In older patients, we always worry about cancer. And recurrent pneumonia can be a sign of a weakened immune system. In any case, an important part of his recovery is taking things slow for a few weeks, even when he feels like he's back to normal.

(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.)