Diet and Liver Health; Gut Microbiome and Cardiometabolic Disease

— Also in TTHealthWatch: COVID hospitalization data

MedicalToday

TTHealthWatch is a weekly podcast from Texas Tech. In it, Elizabeth Tracey, director of electronic media for Johns Hopkins Medicine in Baltimore, and Rick Lange, MD, president of the Texas Tech University Health Sciences Center in El Paso, look at the top medical stories of the week.

This week's topics include recent hospitalization data for COVID-19, the gut microbiome and cardiometabolic disease, diet and steatohepatitis, artificial sweeteners and health.

Program notes:

0:57 MMWR data on COVID and hospitalization

1:57 90% had comorbidity

2:45 Non-sugar sweeteners

3:45 Prevention of non-communicable diseases

4:45 Deleterious impact based on animal studies

5:45 Found in amniotic fluid

6:20 Nonalcoholic fatty liver disease

7:20 Lose 10% of body weight

8:20 Diet can prevent or slow down

8:50 Clinical interventions in gut microbiome

9:50 63% reported frank changes

10:50 Decreasing cardiometabolic disease

11:12 Gut microbiome organ?

12:28 End

Transcript:

Elizabeth: We should be targeting the gut microbiome to reduce our risk for cardiometabolic disease.

Rick: Can nutrition prevent fatty liver disease?

Elizabeth: We need a much more comprehensive view of artificial sweeteners.

Rick: And an update on COVID-19 associated hospitalizations.

Elizabeth: That's what we're talking about this week on TTHealthWatch, your weekly look at the medical headlines from Texas Tech University Health Sciences Center in El Paso. I'm Elizabeth Tracey, a Baltimore-based medical journalist.

Rick: I'm Rick Lange, president of Texas Tech University Health Sciences Center in El Paso, where I'm also dean of the Paul L. Foster School of Medicine.

Elizabeth: Rick, let's just reveal to everyone that we are actually featuring three out of the four studies we're talking about this week that are going to be in an upcoming issue of the The BMJ, and they have convened, along with the Swiss, a very interesting conference taking a look at nutrition and health.

Rick: The so-called Food for Thought. Kudos to The British Medical Journal for highlighting it. Where do you want to start?

Elizabeth: I'm going to let you start actually. Before we foray into that, why don't we first talk about COVID. That's from the Centers for Disease Control and Prevention.

Rick: Okay. In fairness, we couldn't talk about all four studies related to diet or nutrition, but I thought this is really important. What's happened since January till the early or mid part of July is there has been a significant decrease in the number of hospitalizations associated with COVID, but over the last 6 weeks just the opposite has happened. There has been a significant increase and it's disproportionately hit elderly individuals.

What I'm going to report is from Morbidity and Mortality Weekly Report. They said that over the last 6 weeks among adults over 65 years of age hospitalization rates due to COVID have more than doubled. Now, across all age groups, adults aged 65 or older account for two-thirds of the COVID-associated hospitalizations, two-thirds of the intensive care unit admissions, and almost 90% of in-hospital deaths associated with COVID-19.

Among these older individuals, about 90% have underlying medical conditions. Fewer than one quarter had received the recommended COVID-19 vaccine. COVID-related morbidity and mortality disproportionately affects the elderly. Those are the individuals I want to make sure that they get a COVID-19 vaccination that's currently been recommended.

I'll take it a step further. That's meant to prevent both infection and to decrease the severity of infection. But for older individuals and those that are at risk for progression to severe disease, there is also early outpatient treatment. Things like Paxlovid [nirmatrelvir/ritonavir] or remdesivir [Veklury].

Elizabeth: Public health. If you're an older person, get out there and get the appropriate vaccinations for COVID. If you suspect they have it, talk to your primary care doc and try to see if you're eligible for one of these outpatient treatments.

Rick: Let's move on to nutrition. Let's talk about non-sugar sweeteners. Are they helpful or harmful, Elizabeth?

Elizabeth: This is one of their special issues that they talk about and it's entitled "Non-sugar sweeteners: helpful or harmful? The challenge of developing intake recommendations with the available research."

This survey of what's out there already really demonstrates that what we really need are a bunch of studies and they really ought to be peer reviewed. It would be really great if they were randomized, and it would be also really nice if they had much more appropriate follow-up. They note in their beginning of this paper that non-sugar sweeteners have become ubiquitous in a global food supply. Their use is expected to grow, with a predicted market value of $408 billion in 2032.

In May of 2023, the World Health Organization [WHO] said we've got a guideline for people without diabetes that recommends against using non-sugar sweeteners for weight control and the prevention of non-communicable diseases -- of course, cardiovascular largely. For those 10% of the folks in the world who do have diabetes, they still have a lot of confusion relative to the use of these non-sugar sweeteners as a tool for maintaining glycemic control.

They point out in this paper that there are difficulties with many of the arms of research that are out there. The WHO, of course, in looking at this, acknowledged that shorter-term randomized controlled trials did show improvements in body weight and reductions in energy intake when these were used in preference to sugar. However, observational studies have demonstrated that there are long-term detrimental impacts of consuming these non-sugar sweeteners, including increased risk of obesity, type 2 diabetes, cardiovascular disease, and mortality.

Finally, the other thing that they note in here is that many of the perceptions, if you will, about deleterious impact of non-sugar sweeteners are based on animal studies.

Rick: Elizabeth, you highlighted some of the difficulties, but it looks like it would be helpful in the short term, but observational studies suggest it may be harmful in the long term, although there are always caveats with doing observational studies.

A lot of ultra-processed foods contain non-sugar sweeteners and we don't even think about that on our diet. None of the studies have looked at the individual ones, and, gosh, there are six or seven different ones that are available at different doses. There is just a lot of difficulty with interpreting the data. Based upon that, nobody feels comfortable making long-term recommendations for the use of non-sugar sweeteners.

Elizabeth: They also note that the research is even more lacking in other special groups, such as women who are pregnant or breastfeeding, and in children.

Rick: The former is particularly important because it does cross the placental barrier and you can find some of the non-sugar sweeteners in the amniotic fluid. Whether there are long-term effects on the fetus or young child are really unknown and especially in younger children as they are developing as well.

Elizabeth: Their conclusion, of course, is they say we propose that while non-sugar sweeteners may offer a tool for weight management and glycemic control, in some people under certain conditions of use widespread replacement of added sugars with non-sugar sweeteners may have unintended negative consequences, especially in subgroups.

Rick: Their plea to the food companies is not to inundate the food supply with non-sugar sweeteners until we have more evidence about the long-term consequences and their benefits or harms.

Elizabeth: Now, let's talk about the liver.

Rick: Let's talk about nonalcoholic fatty liver disease because we know that excessive alcohol intake can cause fatty liver disease, but one of the more common causes is actually fat accumulation in the liver cells in the people who drink little or no alcohol -- that's strongly associated with other metabolic disorders like obesity, type 2 diabetes, dyslipidemia, and high blood pressure. It also increases the risk of liver cancer.

It's estimated about 30% of the general population has nonalcoholic fatty liver disease that can progress on to fibrosis and scarring, which occurs in about 10% to 15% of people with fatty liver disease. People with obesity are three to five times more likely to develop fatty liver disease and obesity and fatty liver disease and have many of the common pathophysiologic pathways.

A diet that's rich in saturated fatty acids, ultra-processed foods, full-fat dairy products, red meat, even coconut oil and palm oils -- and also increased ingestion of sugar supplies -- contributes to the risk of fatty liver disease.

If you lose 10% of your body weight through lifestyle modifications, such as reducing your caloric intake and using exercise, it can help promote the resolution of the fatty liver inflammation and help progress some of the fibrosis. This is a plea to change our nutrition to either prevent fatty liver disease or to prevent the progression of fatty liver disease.

Elizabeth: I see plenty of folks who unfortunately are in the last or later stages of this, who then are being evaluated as candidates for liver transplant. That, of course, is something that we're seeing increasing worldwide also.

Rick: Yep. For people that are concerned about this -- and we all ought to be concerned about it -- there are a number of different diets that could be useful like the Mediterranean diet. It's rich in vegetables, fruits, beans, whole grains, and fish. Also, the DASH [Dietary Approaches to Stop Hypertension] diet, which we oftentimes prescribe in the United States. These are more likely to prevent the occurrence or progression of nonalcoholic fatty liver disease.

Elizabeth: I am a little bit startled by the prevalence of this condition. Does this suggest to you that we ought to be doing some kind of routine screening for it?

Rick: That is one of the things that they make a plea for, especially in high-risk groups -- those with diabetes and those with obesity -- and then to provide nutritional support and policies that would help encourage dietary changes.

Elizabeth: Then, finally in this issue we're going to take a look at the evidence for clinical interventions targeting the gut microbiome in, I'm going to say, avoiding cardiometabolic disease -- i.e., hypertension, diabetes, and obesity largely.

There are lots of studies that are out there taking a look at the gut microbiome and whether we're able to really influence the gut microbiome and in a way that might end up being beneficial. They identify three categories of these kinds of interventions, what are known as (1) probiotics -- those are collections of bacteria and so forth that are ostensibly going to be beneficial; (2) prebiotics, which are dietary things that you can consume that will change your gut microbiota; and then finally (3) synbiotics, which is both of them.

They found in their look at the literature that over 70% of clinical intervention studies found that there were significant improvements in cardiometabolic traits with the use of an attempt to influence the gut microbiome, although only 63% reported frank changes to that microbiome. It's notoriously difficult to assess that because how do you actually get inside there and figure out what you got in there in your gut microbiome.

They did find that prebiotic interventions are the most likely to result in changes to the gut microbiome composition followed by dietary interventions and then probiotics. Probiotics we can eat and drink all those kinds of bacteria, but the likelihood that they're going to actually get in there and colonize our gut is pretty low. They also found that the single strain is better than a multistrain probiotic and synbiotic intervention.

If you're going to attempt to change your microbiome, do it with a single kind of a bug versus a bunch of them.

Rick: Prebiotics are substrates or molecules that promote the growth of beneficial gut bacteria. One of the most common prebiotics is actually fiber. It gets back to the diet and what we originally called as food for thought in terms of decreasing cardiometabolic disease, decreasing nonalcoholic fatty liver disease, and in changing the gut microbiome. What that change in gut microbiome does is it decreases the inflammation and provides antioxidants.

Elizabeth: They make a statement in here that I think is really interesting and kind of provocative. I want to hear your response to it. They say we can regard the gut microbiome as an externally modifiable organ of the human body.

Rick: I thought that was probably one of the best descriptions I have heard. Affecting it can dramatically change the trajectory of cardiometabolic disease. I can say that I'm not sure we appreciated this 20 years ago.

Elizabeth: Not even close. I mean, when we first started podcasting we never talked about the microbiome at all. They also point out that it's got these three functions: a sensor function, a modulator function, and finally a translator function, because, of course, it does metabolize and then subsequently release into the body a lot of other things that impact directly on our health. You're going to start consuming a lot more of these things?

Rick: Over the last 5 to 10 years, I have made it a habit of eating healthier, not only when we're eating out, but more important when we're eating at home. I like to think my microbiome is in better shape than it was a decade ago.

Elizabeth: But one of these days we're going to get an assessment of that and we're going to find out. On that note then, that's a look at this week's medical headlines from Texas Tech. I'm Elizabeth Tracey.

Rick: I'm Rick Lange. Y'all listen up and make healthy choices.