Hello, dear readers! Welcome to our monthly letters column. With long days, warm nights and plenty of outdoor living, it’s time for our annual summertime reminders. Please protect yourselves from the sun, take precautions against ticks and mosquitoes, always watch children playing in water, and never underestimate the physical threats of a heat wave. And now, on to your letters.

-- We recently wrote about shingles, a painful, blistering rash caused by the same virus that causes chickenpox. This led to a question from a reader in Naples, Florida. “Your column did not include the likelihood of a person who has never had chickenpox possibly getting shingles,” he wrote. “My girlfriend is 64 and has never had chickenpox or the vaccine, and I’m worried about her.” Shingles is a reactivation of the chickenpox virus in someone who has had that illness. That means you cannot get shingles if you’ve never had chickenpox. However, it is possible to have been infected with chickenpox without developing the distinctive rash it causes and not be aware that you had the illness. Without the immunity conferred by either a previous case of chickenpox or the vaccine, your girlfriend is at risk of contracting the illness. This can occur through exposure to someone with chickenpox or contact with fluids from a shingles blister. Shingles itself is not contagious, but the underlying virus that causes it can spread to susceptible individuals during an active flare-up.

-- Several columns have focused on stem cell research to manage or cure Type 1 diabetes. This letter from a reader echoes questions from several parents. “I saved my son’s cord blood and placenta at delivery,” she wrote. “Can these stored tissues be used in a clinical trial for a diabetes cure?” Cord blood and the placenta are indeed a rich source of stem cells. These are "blank slate" cells with the potential to turn into specialized cells. While researchers are exploring how stem cells can be used to trigger insulin production, at this time the studies do not include the use of a participant’s own cord blood or placental tissues. To learn more about current and future research into stem cells and Type 1 diabetes, visit clinicaltrials.gov and search for Type 1 diabetes and stem cells.

-- A column about a possible connection between emotional stress and lower back pain prompted this letter from a reader in Huntley, Illinois. “It seems to me you covered everything but the cure,” he wrote. “All people have to do to rid themselves of lumbar aches and pains is to properly perform the bridge pose and the plank pose for a few minutes every day.” Although the column did include information about medications, heat therapy and physical therapy, you are correct that we did not discuss a role for yoga. We appreciate you sharing your own approach to a challenging form of back pain.

Thank you, as always, for taking the time to write to us. We look forward to hearing from more of you. We will be back soon with a bonus letters column with more of your follow-up questions and comments.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: I am a vegan, and after a meal, I have uncomfortable and smelly intestinal gas. It has only ever eased when I took an antibiotic and after colonoscopy prep. I assume that’s because these killed my gut bacteria. Is there a fast way to reset the gut? Is this problem a health risk?

Dear Reader: The gut microbiome refers to the remarkable and complex ecosystem of trillions of bacteria, fungi, viruses and other microorganisms that make their home in our gut. While some are found in the small intestine, the vast majority live in the large intestine. Research continues to uncover new ways that the composition, diversity and health of these colonies of microorganisms affect our health. The microbes we host have a direct influence on diverse processes such as digestion, nutrient absorption, cardiovascular and neural health, immune response and even brain health and function.

You are correct that a primary cause of intestinal gas is the metabolic activity of bacteria in the gut. It has to do with dietary fiber, which is a complex carbohydrate. Unlike simple carbs, which get absorbed into the bloodstream in the small intestine, fiber passes undigested into the colon, or large intestine. There, the cellulose, pectin, lignin, hemicellulose, mucilage and other cell remnants that survived the digestive process become food for the resident bacteria.

First, enzymes produced by the bacteria dismantle the complex carbs. Then, through fermentation, the resulting simple sugars get processed into short-chain fatty acids the bacteria can absorb. One of the byproducts of that fermentation is -- you guessed it -- intestinal gas.

In your case, several considerations come to mind. As a plant-forward vegan, your diet contains a significant amount of plant-based fiber. Cruciferous vegetables such as broccoli, cabbage and cauliflower; foods that contain sulfur such as garlic and onions; and beans and legumes are associated with robust and sometimes smelly gas production. Some vegans who experience excessive gas find it useful to subtract, then gradually reintroduce, specific foods to help identify any that may be problematic. Some people then choose to limit or eliminate those foods.

It’s true that antibiotics and colonoscopy prep can significantly alter the balance of intestinal flora. Research shows that, when used only occasionally, antibiotics don’t cause lasting damage. Gut recovery can take anywhere from several weeks to a few months, so be patient. You can boost your gut recovery by eating dietary fiber from a wide range of sources. This can also temporarily increase intestinal gas.

Excessive gas production is not a health risk. It can sometimes be a symptom of an underlying disease or condition such as Crohn’s disease, irritable bowel syndrome (IBS), ulcerative colitis or small intestinal bowel overgrowth (SIBO). If changes to your diet don’t have a beneficial effect on gas production, check in with your health care provider for guidance.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Kansas City, MO 64106; 816-581-7500

Dear Doctors: I am 68 years old, and I am going to need a hip replacement. I’ve been reading about it, and some people say that you can prepare yourself physically so that you will do better after the surgery. Do you know if this works? If so, what do you need to do, and when?

Dear Reader: This approach to surgery is known as prehabilitation, or prehab. While rehabilitation (rehab) focuses on recovery after orthopedic surgery, prehab focuses on preparing before surgery. The idea is that increasing physical strength and stamina can lead to a better and faster post-surgical recovery.

In hip replacement surgery, the damaged portions of bone and cartilage in the hip joint are removed. The surgeon then replaces them with new implants made of a combination of metal, ceramics and polymers or plastics. After surgery, patients often deal with limited mobility and decreased muscle strength. This is particularly true in early recovery.

Research into prehab has shown it can help patients recover strength and range of motion more quickly than those who don’t prepare. This, in turn, gets them on their feet and mobile in a shorter time frame. Prehab has also been shown to reduce the need for follow-up inpatient care.

A prehab program for hip replacement often begins six to eight weeks before surgery. It should be done with a physical therapist, who will begin with an in-depth assessment. This is important because the pain and limited range of motion that trigger the need for a hip replacement often affect the biomechanics of how you walk, sit, stand and move. Exercises typically focus on strengthening the muscles of the back, legs and core, and include a cardio component to improve stamina. It can also be helpful for people to learn about the exercises they will perform following their surgery.

Some prehab programs include guidance on how to prepare your home for a safe recovery. This includes removing tripping or slipping hazards, such as area rugs, electrical cords or ground-level decor. Another important part of prehab is selecting and learning how to use the support and stability devices you will need in the early days of recovery. These may be crutches, a walker with or without wheels, or a walking cane. Not surprisingly, diet also plays a key role. You can boost your body’s ability to heal by getting plenty of lean protein, fatty fish, fresh vegetables, leafy greens and fruit; cooking with healthy oils; limiting alcohol; and avoiding ultra-processed foods and added sugars.

The data show that people who complete a prehab program can have a faster recovery with less pain, less downtime and less need for post-operative care. If you would like to prepare for your own surgery with a prehab program, ask your doctor to recommend a physical therapist with experience in prehab.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Kansas City, MO 64106; 816-581-7500