Dear Doctor: What are the possible health risks from artificial sweeteners? What are they, and how do we know if they're safe?

Dear Reader: It's been well over a century since a scientist at Johns Hopkins University who was fiddling around with the byproducts of coal tar (that's right, coal tar) accidentally discovered saccharine. It caused a sensation, and a decade later saccharine, which scientists estimate to be between 200 and 700 times sweeter than table sugar, could be found in many sodas and some canned foods.

Since then, as you noted, a host of new artificial sweeteners have hit the market. Some, like cyclamates, which were linked to bladder cancer in lab rats, were subsequently withdrawn. Others, despite undergoing rigorous study before getting approval from the Food and Drug Administration, continue to be the focus of skepticism and scrutiny.

At this time, six artificial sweeteners, also known as "non-nutritive" and "high-intensity" sweeteners -- have received FDA approval. These are saccharine, sucralose, aspartame, acesulfame potassium, neotame and advantame. Each is at least several hundred times sweeter than sugar. Advantame is said to be 20,000 times sweeter than sugar. It, along with all the other FDA-approved artificial sweeteners except saccharine and aspartame, is heat-stable. That means these can be used in baking.

Stevia, a sweetener made from the leaf extract of a plant native to parts of South America, gets a Generally Recognized as Safe (GRAS) nod from the FDA. That means it doesn't need formal approval for use. However, the stevia leaf itself, as well as crude stevia extracts, are not cleared for use at this time.

Artificial sweeteners have undergone years of testing in order to get approval from the FDA, which means they are considered safe for human consumption. Sucralose, for instance, was studied for 20 years before getting FDA approval. However, as we mentioned before and as your letter illustrates, not everyone feels comfortable with these products.

Some subsequent studies linked various artificial sweeteners to health problems in the rats and mice used in experiments. But when this research underwent scrutiny by groups such as the National Cancer Institute, it was determined that inconsistencies in the data prevented clear conclusions from being drawn.

A fascinating group of studies has suggested that, contrary to their no-calorie logic, artificial sweeteners don't help with weight loss. In fact, the promise of sweetness without the caloric payoff actually backfires. It sets off a chemical reaction in the brain that results in increased craving for sweets. And because seemingly every discussion of health and well-being these days now leads to the gut, there is evidence that artificial sweeteners can adversely affect the numbers and diversity of the friendly bacteria in our intestines.

While artificial sweeteners can be a boon to people with conditions like diabetes, we believe that for the rest of us, they should be an occasional, rather than a regular, part of our diets.

(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.)

(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: What are the best ways to cope with herpes simplex 2?

Dear Reader: Herpes simplex 2 is a sexually transmitted disease, or STD. Herpes simplex 1, which is also called oral herpes, causes cold sores or fever blisters on or around the mouth and lips. Herpes 1 can also be transmitted to the genitals. However, the majority of cases of genital herpes are caused by herpes simplex 2. Both types of herpes are viruses.

Herpes is a common STD. According to the Centers for Disease Control and Prevention, one in every six Americans is infected with genital herpes. The infection is acquired through contact with the herpes virus, which can be present in lesions or sores on the genitals or anus, in mucosal secretions and even on the skin. Even without an active outbreak, the herpes virus can be transmitted to sex partners. In many cases of transmission, the infected partner doesn't realize he or she has the virus. It is estimated there are between 750,000 and 1 million new cases of herpes simplex 2 in the United States each year.

Symptoms of an outbreak include the lesions previously mentioned, as well as localized genital pain. Possible but less common are tingling sensations or shooting pains in the legs, hips or buttocks. Perhaps the most serious complication of a genital herpes infection is the chance of spreading it during childbirth. Neonatal herpes infections, while rare, can be fatal. Pregnant women with herpes should let their doctors know about their infection.

At this time, there is no cure for either oral or genital herpes. Antiviral drugs like acyclovir, famciclovir and valacyclovir can help to reduce the severity of symptoms and the frequency of outbreaks of herpes 2. That means that individuals who are infected with the virus have a lifelong condition that must be managed.

As for how to manage a genital herpes infection, the main concern is to not spread it to sexual partners. Herpes is at its most contagious when sores or lesions are present. However, we must repeat that it can be transmitted at any time, whether or not there are visible symptoms.

During outbreaks that involve sores, infected individuals should abstain from sex. (And if you're having sex with someone and see genital sores, stop.) The difficult truth is that, even when sores are not present, condoms are only partially successful at preventing transmission of the virus. That's because the virus can be present in areas that are not covered by the condom.

If either you or your romantic partner has genital herpes, the risk of transmitting the virus can be lessened by taking an antiviral medication. The medication lowers the incidence of visible outbreaks, which is when the risk of acquiring the virus is highest. You should also avoid any kind of sex with your partner during an outbreak. Anyone with herpes simplex 1, which causes cold sores, should never engage in oral sex, as it can result in a genital infection in their partner.

Anyone who suspects he or she has herpes should see a doctor. A visual examination of an active sore, culturing a sore or a blood test for antibodies will give you an answer.

Dear Doctor: My husband, who has been diagnosed with a sleep disorder, acts out all his dreams. He recently tore his rotator cuff and dislocated his shoulder when he fell out of bed during a dream about playing basketball. We're worried this might happen again. Are there any new treatments or research into this disorder?

Dear Reader: It sounds as though you're describing what's known as REM Sleep Behavior Disorder. This happens when an individual overcomes the natural paralysis that typically accompanies the dream state and literally engages in the physical activities of the dream.

We spend our time in two basic stages when we sleep. There's REM (rapid eye movement) sleep, which is when we dream. And there's non-REM sleep, which is made up of several different stages of deeper sleep. Throughout the night, we cycle through these different stages, with up to a quarter of the time spent in REM sleep, and the rest in the various stages of non-REM sleep.

During REM sleep, blood pressure goes up, breathing becomes uneven, the eyes dart back and forth, and the brain is extremely active. In normal REM sleep, a natural paralysis sets in, which ensures that our dreams remain in our minds and don't cross into the physical realm. However, in REM Sleep Behavior Disorder, also known as RBD, that paralysis is either incomplete or not present at all. As a result, the sleeper takes an active part in those dreams.

The behaviors of RBD range from speaking, shouting and swearing in one's sleep, to running, leaping, grabbing and punching. Patients report that their dreams are always active, and often violent. Although this time it was your husband who was hurt, those who share a bed with someone with RBD are also at risk of physical injury.

At this time, treatment consists of making the bedroom safer for the patient and his or her bed partner, and medications for the patient. Padding on, around and below the bed, lowering the bed itself, and de-cluttering and removing potentially dangerous objects, is recommended. When it comes to medications, the anti-anxiety drug klonopin has been shown to be effective. Sometimes melatonin, a regulator of the sleep cycle, is prescribed as well.

Although the cause of REM Sleep Behavior Disorder is not yet known, studies have found a link between the disorder and the future onset of degenerative neurological conditions like Parkinson's disease. According to the authors of the most recent study, published in the journal Neurology Today in September 2017, up to 75 percent of patients eventually develop Parkinson's or a related condition. The thinking is that the symptoms of RBD indicate neurological changes that precede the symptoms of Parkinson's and other similar disorders.

We realize this sounds alarming, which is why we urge you and your husband to get a second opinion at a recognized sleep center. Your husband will undergo a physical and neurological exam, may be asked to undergo an overnight sleep study, and you may be interviewed for details about his sleep patterns. If the RBD diagnosis proves accurate, you will then be in good hands to deal with the disorder.

(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.)