Hello again, dear readers! How is 2018 treating you so far? Thank you, as ever, for your emails and letters. Your kind comments warm our hearts; your criticisms make us want to do better; and your questions, comments and opinions widen our worldview. And on that note, onward!

-- After our column about teething remedies was published, we received quite a few questions regarding the purported benefits of amber teething necklaces. These necklaces have become popular teething aids in some parts of the country. Amber, which is fossilized tree resin, has long had a role in folk medicine. When it comes to teething, the idea is that the succinic acid contained in Baltic amber will be absorbed via the skin and confer therapeutic effects.

While it's true that Baltic amber does contain small amounts of succinic acid, we were unable to find any research that shows it acts as an analgesic, that body heat will cause it to be released or that it can be absorbed through the skin. Even if the above were possible, the dose of succinic acid available in an amber necklace would be miniscule. Add in the choking hazard presented by the size of the amber beads and a recent study that found these necklaces to be associated with bacterial colonization, and our position is that the very real risks outweigh the unproven benefits.

-- A recent column about portion control showed us how creative you readers are. The range and variety of visual guidelines you use for portion control has been fascinating to see. We particularly liked this whole-plate approach to making sure a meal doesn't stray into overeating:

"Make it simple," writes Noreen, who uses a small salad plate as her template. She fills two-thirds of the plate with vegetables, then fills the remaining space with meat or a meat substitute, and a serving of fruit. Noreen reverses the typical American approach and eats her largest meals at breakfast and lunch and goes light on dinner.

-- And, finally, thank you to a reader for adding to our discussion of urinary incontinence.

"You have mentioned stress incontinence in your column a couple of times recently, but I don't recall that there was any mention of obesity as a contributing factor," our reader points out. "If weight loss can be part of treatment for UI, it would be helpful to know for people who have both of those conditions."

You're right -- a number of studies have shown a clear link between obesity and urinary incontinence. Individuals who are overweight experience an increase in intra-abdominal pressure. This has the effect of increasing pressure on the pelvic floor, including the bladder and the bowel, and plays a role in developing urinary incontinence, or UI.

The good news is that several studies have shown that weight loss can significantly reduce the number of stress incontinence episodes experienced by participants. In fact, weight loss, along with exercise, is recommended as a first-line treatment for urinary incontinence among individuals who are significantly overweight.

(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: I recently read about a sugar additive being linked to the rise of a killer bug. What is this additive, how do I avoid it, and how serious is the threat?

Dear Reader: Clostridium difficile, or C. diff, is a bacterium that can cause severe intestinal infections, leading to severe diarrhea, possible hospitalizations and even death, especially in people over the age of 65. Antibiotic use is often the precipitating factor in C. diff infections because the drugs kill off the normal bacterial populations in the colon and allow for C. diff to multiply and release toxins, triggering inflammation and diarrhea. Rates of C. diff infection are increasing in this country, with nearly 500,000 people per year affected and 15,000 deaths. Use and overuse of antibiotics are blamed for this increase. But a recent study in the journal Nature may point to another factor.

First, note that C. diff has different subtypes, or ribotypes, with two strains in particular -- RT027 and RT078 -- associated with large outbreaks of disease. These outbreaks have been common since the year 2000. The year is important because that's when the sugar trehalose became available for mass production and began to be readily placed in foods and drinks. Of course, many notable things occurred in the year 2000, so let's explore how a sugar product could specifically be blamed for an increase in the risk of C. diff outbreaks.

Trehalose is a naturally occurring sugar produced by plants, fungi, bacteria and insects that helps organisms retain water and prevents cellular damage when there is no water. It's about 45 percent as sweet as sucrose (or table sugar), but researchers for years lacked a cost-effective way to extract it. However, in 2000, a new enzymatic extraction method led to a cheap way to mass-produce trehalose. Subsequently, many food products and drinks were produced with this sugar as an ingredient.

The study you are referencing looked at how the C. diff ribotypes RT027 and RT078 respond to trehalose. For starters, RT027 will grow five times greater than other ribotypes of C. diff when trehalose is a food source. Also, RT027 needs lower concentrations of trehalose to turn on enzymes that metabolize the sugar. Mice infected with the RT027 type were three times as likely to die when given a solution that mimicked human intake of trehalose compared with those given water. The ribotype RT078 also shows an increased ability to metabolize trehalose.

Further, the small intestine doesn't absorb trehalose as well as it does sucrose. This leads to more trehalose ending up in the large intestine, which is where C. diff causes its damage. Thus, if a patient has an RT027 or RT078 strain of C. diff and trehalose is present in the large intestine, the bacteria can readily use trehalose to survive and multiply. These bacteria will also have a competitive advantage over other bacteria in the colon that cannot utilize trehalose.

It's one of those quirks of nature that a bacterium can use a naturally occurring substance to its benefit -- and our detriment. I would look at food labels and evaluate whether your diet is high in this sugar. If so, you might want to make adjustments. The data are concerning.

(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: I'm 26 years old and have been diagnosed with lymphedema in all four limbs. I'm 5 feet 8 inches and weigh 193 pounds. I work out for an hour every morning and am physically active. What else can I do to help my lymphedema?

Dear Reader: Lymphedema is the swelling that occurs in the arms, legs or other parts of the body when the lymphatic system is not functioning properly. It's most common in cancer patients who have had lymph nodes either removed or damaged during surgery or treatment. Swelling caused by injury to the lymphatic system is known as secondary lymphedema. When the swelling occurs independent of surgery or other damage, as in your case, the condition is known as primary lymphedema.

The lymphatic system, which is part of the immune system, is a circulatory system that includes all the tissues and organs that produce, store and carry white blood cells. A crucial part of this system is the network of lymphatic vessels that serve tissues throughout the body. Similar to capillaries, these are thin-walled tubes that drain fluid from the tissues and carry it to the lymph nodes. Unlike capillaries, however, which have the force of the heartbeat to move the blood within them, the lymphatic system is largely dependent on muscle movement to keep things flowing.

The type of lymphedema you have is quite rare. It's an inherited condition in which the lymph vessels have not formed properly. As a result, the protein-rich lymph collects in the layers of soft tissue beneath the skin. This causes swelling in one or both legs, one or both arms, and can also affect the face and trunk.

When you have lymphedema, it's important to seek professional care. The condition puts you at higher risk of developing infections of the skin and underlying tissues, which in turn can lead to abscesses, ulcers and tissue damage. Something as simple as a scratch or cut or insect bite can lead to serious infection.

There is no known cure for lymphedema, and no FDA-approved medication. However, complete decongestive therapy, also known as CDT, is an important tool in controlling the condition. In CDT, a lymphedema therapist leads you through a comprehensive program that includes manual lymphatic drainage, bandaging, the use of compression garments and self-care.

Manual lymphatic drainage, performed by the therapist, uses a feather-light touch to move lymph from the tissues and direct it back into the lymphatic vessels. Compression garments, which are made from flexible fabrics, keep a steady pressure on the affected limb and keep lymph moving.

Self-care includes protecting your limbs from cuts, scrapes, insect bites, overuse and extreme temperatures. Maintaining a healthy body weight is important in managing lymphedema. So is regular exercise, which you've already incorporated into your life. Be sure to run the specifics of your routine by your lymphedema therapist.

Managing lymphedema takes sustained effort and attention. That's why, once again, we're going to urge you to work with specialists in the field. For help finding a lymphedema therapist, visit the National Lymphedema Network at lymphnet.org.

(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.)