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 Some, like cyclamates, which were linked to bladder cancer in lab rats, were subsequently withdrawn.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 UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: We’re all pretty stressed-out, even the kids. I keep saying that spending a Saturday in the nice park near our house could help, but my husband just laughs. Isn’t there some kind of research that being outdoors is good for you?

Dear Reader: Just thinking about a walk under the open sky as we began our answer to you brought about a sigh of relief. It makes sense, because long before we humans started spending so much time in built environments, we were deeply connected to the natural world. Many people have an innate understanding about that connection, and years of research backs them up.

Studies show that regularly spending time outdoors confers a host of mental health benefits. These include relief of anxiety and stress, a boost to feelings of calm, enjoyment and well-being, and improvements to mood and attitude. And that’s not taking into account the positive effect that even mild exercise, like walking, has on the body.

It seems like the link between time spent in nature and emotional well-being would be hard to prove, but researchers from the University of Michigan in Ann Arbor found a way. In fact, according to their study, published in 2019 in the journal Frontiers in Psychology, as little as 20 minutes spent outside in nature can have a healing effect. As an added surprise, their study showed the connection holds up even when the green space is in an urban environment.

Over the course of two months, the researchers had 36 volunteers spend at least 10 minutes three times per week in a variety of outdoor environments. These included public parks, the green spaces near their places of work or their own backyards. The participants could either sit still or stroll around during their outdoor time, but they were banned from chatting, reading or using screens of any kind. In order to rule out the known benefits of exercise, they were also asked to refrain from vigorous physical activity prior to their nature walks.

Before and after each outing, samples of saliva, which contains the stress hormone cortisol, were collected from each volunteer. Analysis of the saliva samples revealed that the volunteers returned from their nature outings with lower levels of cortisol than they started out with. Surprisingly, the biggest drops in the stress hormone occurred in the first 20 to 30 minutes of nature immersion. Benefits continued after that, but more gradually. Neither the time of day that someone chose to be outdoors nor where they spent their time played a role in the stress reduction. According to this study, the simple act of stepping outside into a green space began to bring relief.

The time frame that this study reveals is certainly new, but research about the benefits of spending time in nature dates back to the 1970s. We hope that, with proximity to a park and the low bar of 20 to 30 minutes, you’ll be able to persuade your family to make being outdoors a regular part of their lives.

(Send your questions to askthedoctors@mednet.ucla.edu. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: Is there more than one kind of COVID-19? I heard on the news about something they’re calling “long COVID,” and it sounds like a whole different kind of disease. How do you get it? Can it be cured?

Dear Reader: It’s true that we’re hearing a lot about long COVID these days. Despite being referred to by a different name than COVID-19, it’s not a separate illness. Rather, long COVID is a term used to describe the lingering symptoms that can affect some people who have survived COVID-19. People who are experiencing long COVID are sometimes referred to as "COVID long-haulers."

As we know all too well by now, COVID-19 is the name of the illness that can arise when someone becomes infected with the novel coronavirus. Cases of COVID-19 run the gamut from mild to moderate to severe to fatal. One of the perils of the disease is that it’s impossible to predict how any one person will react to the infection. Even a moderate case of COVID-19 can be challenging, with symptoms that include high fever, body aches, congestion, difficulty breathing, dizziness, profound fatigue and altered mental status. For many people with moderate to severe COVID-19, the disease runs its course in a month or more. However, tens of thousands of survivors experience long COVID, or long-haul COVID, and some symptoms persist.

For these COVID survivors, recovery is long and rocky, marked by repeated setbacks. Even when the worst of the disease has run its course, other symptoms affect patients for many months. These include persistent fatigue, exhaustion, headache, muscle aches, muscle spasms, erratic heartbeat, depression, low blood pressure after exertion and memory fog. Some patients experience increased blood clotting, which can lead to organ damage.

A recent study published in the Journal of the American Medical Association followed the recovery of 145 patients in their 50s who had experienced moderate to severe COVID-19 symptoms. Researchers found that 87% were left with labored breathing and persistent fatigue for months after the initial disease. Another troubling aspect of long COVID is emerging evidence that it can affect the youngest survivors. About 10% of the more than 11 million coronavirus infections reported in the U.S. thus far have occurred in children, and many experience long-lasting symptoms.

It’s still not clear why some people recover completely from COVID-19, while for others symptoms persist for months. One theory is that, even after someone recovers from the initial disease, fragments of the genetic code of the coronavirus may continue to circulate throughout the body. Although these fragments don’t cause full-on disease, they may continue to trigger an immune system response.

At this time, as with COVID-19, there is no single cure for long COVID. Treatment focuses on managing symptoms. However, it has been recognized as a serious problem. Researchers are now launching studies to discover the biological and immunological causes of long-haul COVID. The hope is to identify any biomarkers that make people susceptible to the syndrome and point to successful treatments.

(Send your questions to askthedoctors@mednet.ucla.edu. Owing to the volume of mail, personal replies cannot be provided.)