Thursday, January 12, 2023

Consumption of fast food linked to liver disease

Risk of liver damage is highest for those with obesity or diabetes

UNIVERSITY OF SOUTHERN CALIFORNIA - HEALTH SCIENCES

Ani Kardashian, MD, a hepatologist with Keck Medicine of USC, is the lead author of a new study showing that fast-food consumption is linked to liver disease. — IMAGE: ANI KARDASHIAN, MD, A HEPATOLOGIST WITH KECK MEDICINE OF USC, IS THE LEAD AUTHOR OF A NEW STUDY SHOWING THAT FAST-FOOD CONSUMPTION IS LINKED TO LIVER DISEASE. view more
CREDIT: RICARDO CARRASCO III

LOS ANGELES — The new year has begun, and with it, resolutions for change.

A study from Keck Medicine of USC published today in Clinical Gastroenterology and Hepatology gives people extra motivation to reduce fast-food consumption.

The study found that eating fast food is associated with nonalcoholic fatty liver disease, a potentially life-threatening condition in which fat builds up in the liver.

Researchers discovered that people with obesity or diabetes who consume 20% or more of their daily calories from fast food have severely elevated levels of fat in their liver compared to those who consume less or no fast food. And the general population has moderate increases of liver fat when one-fifth or more of their diet is fast food.

“Healthy livers contain a small amount of fat, usually less than 5%, and even a moderate increase in fat can lead to nonalcoholic fatty liver disease,” said Ani Kardashian, MD, a hepatologist with Keck Medicine and lead author of the study. “The severe rise in liver fat in those with obesity or diabetes is especially striking, and probably due to the fact that these conditions cause a greater susceptibility for fat to build up in the liver.”

While previous research has shown a link between fast food and obesity and diabetes, this is one of the first studies to demonstrate the negative impact of fast food on liver health, according to Kardashian.

The findings also reveal that a relatively modest amount of fast food, which is high in carbohydrates and fat, can hurt the liver. “If people eat one meal a day at a fast-food restaurant, they may think they aren’t doing harm,” said Kardashian. “However, if that one meal equals at least one-fifth of their daily calories, they are putting their livers at risk.”

Nonalcoholic fatty liver disease, also known as liver steatosis, can lead to cirrhosis, or scarring of the liver, which can cause liver cancer or failure. Liver steatosis affects over 30% of the U.S. population.

Kardashian and colleagues analyzed the most recent data from the nation’s largest annual nutritional survey, the 2017-2018 National Health and Nutrition Examination Survey, to determine the impact of fast-food consumption on liver steatosis.

The study characterized fast food as meals, including pizza, from either a drive-through restaurant or one without wait staff.

The researchers evaluated the fatty liver measurement of approximately 4,000 adults whose fatty liver measurements were included in the survey and compared these measurements to their fast-food consumption.

Of those surveyed, 52% consumed some fast food. Of these, 29% consumed one-fifth or more daily calories from fast food. Only this 29% of survey subjects experienced a rise in liver fat levels.

The association between liver steatosis and a 20% diet of fast food held steady for both the general population and those with obesity or diabetes even after data was adjusted for multiple other factors such as age, sex, race, ethnicity, alcohol use and physical activity.

“Our findings are particularly alarming as fast-food consumption has gone up in the last 50 years, regardless of socioeconomic status,” said Kardashian. “We’ve also seen a substantial surge in fast-food dining during the COVID-19 pandemic, which is probably related to the decline in full-service restaurant dining and rising rates of food insecurity. We worry that the number of those with fatty livers has gone up even more since the time of the survey.”

She hopes the study will encourage health care providers to offer patients more nutrition education, especially to those with obesity or diabetes who are at higher risk of developing a fatty liver from fast food. Currently, the only way to treat liver steatosis is through an improved diet.

Jennifer Dodge, MPH, assistant professor of research medicine and population and public health sciences at the Keck School of Medicine of USC and Norah Terrault, MD, MPH, a Keck Medicine gastroenterologist and division chief of gastroenterology and liver diseases at the Keck School, were also authors on the study.

###

For more information about Keck Medicine of USC, please visit news.KeckMedicine.org.

JOURNAL

Clinical Gastroenterology and Hepatology

DOI

10.1016/j.cgh.2022.11.040

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Quantifying the Negative Impact of Fast-Food Consumption on Liver Steatosis Among U.S. Adults with Diabetes and Obesity

ARTICLE PUBLICATION DATE

10-Jan-2023

It would take 23 million years for evolution to replace Madagascar’s endangered mammals

“Now or never” for preventing extinction

Peer-Reviewed Publication

FIELD MUSEUM

Mouse lemur — IMAGE: BROWN MOUSE LEMUR, ONE OF THE 104 SPECIES OF LEMURS THAT ARE CURRENTLY THREATENED WITH EXTINCTION. A TOTAL OF 17 SPECIES OF LEMURS HAVE GONE EXTINCT SINCE HUMANS ARRIVED ON MADAGASCAR. view more
CREDIT: © CHIEN C. LEE

In many ways, Madagascar is a biologist’s dream, a real-life experiment in how isolation on an island can spark evolution. About 90% of the plants and animals there are found nowhere else on Earth. But these plants and animals are in major trouble, thanks to habitat loss, over-hunting, and climate change. Of the 219 known mammal species on the island, including 109 species of lemurs, more than 120 are endangered. A new study in Nature Communications examined how long it took Madagascar’s unique modern mammal species to emerge and estimated how long it would take for a similarly complex set of new mammal species to evolve in their place if the endangered ones went extinct: 23 million years, far longer than scientists have found for any other island.

That is, simply put, really bad news. “It's abundantly clear that there are whole lineages of unique mammals that only occur on Madagascar that have either gone extinct or are on the verge of extinction, and if immediate action isn't taken, Madagascar is going to lose 23 million years of evolutionary history of mammals, which means whole lineages unique to the face of the Earth will never exist again,” says Steve Goodman, MacArthur Field Biologist at Chicago’s Field Museum and Scientific Officer at Association Vahatra in Antananarivo, Madagascar, and one of the paper’s authors.

Madagascar is the world’s fifth-largest island, about the size of France, but “in terms of all the different ecosystems present on Madagascar, it’s less like an island and more like a mini-continent,” says Goodman. In the 150 million years since Madagascar split from the African mainland and the 80 million since it parted ways with India, the plants and animals there have gone down their own evolutionary paths, cut off from the rest of the world. This smaller gene pool, coupled with Madagascar’s wealth of different habitat types, from mountainous rainforests to lowland deserts, allowed mammals there to split into different species far more quickly than their continental relatives.

But this incredible biodiversity comes at a cost: evolution happens faster on islands, but so does extinction. Smaller populations that are specially adapted to smaller, unique patches of habitat are more vulnerable to being wiped out, and once they're gone, they're gone. More than half of the mammals on Madagascar are included on the International Union for Conservation of Nature Red List of Threatened Species, aka the IUCN Red List. These animals are endangered primarily because of human actions over the past two hundred years, especially habitat destruction and over-hunting.

An international team of Malagasy, European, and American scientists, including Goodman, collaborated to study the looming extinction of Madagascar’s endangered mammals. They built a dataset of every known mammal species to coexist with humans on Madagascar for the last 2,500 years. (Humans have lived on the island, perhaps intermittently, for the past 10,000 years, but have remained constant there for the last 2,500.) The scientists came up with the 219 known mammal species alive today, plus 30 more that have gone extinct over the past two millennia, including a gorilla-sized lemur that went extinct between 500 and 2,000 years ago.

Armed with this dataset of all the known Malagasy mammals that interacted with humans, the researchers built genetic family trees to establish how all these species are related to each other and how long it took them to evolve from their various common ancestors. Then, the scientists were able to extrapolate how long it took this amount of biodiversity to evolve, and thus, estimate how long it would take for evolution to “replace” all of the endangered mammals if they go extinct.

To rebuild the diversity of land-dwelling mammals that have already gone extinct over the past 2,500 years, it would take around 3 million years. But more alarmingly, the models suggested that if all the mammals that are currently endangered were to go extinct, it would take 23 million years to rebuild that level of diversity. That doesn’t mean that if we let all of the lemurs and tenrecs and fossas and other unique Malagasy mammals go extinct, that evolution will recreate them if we just wait around 23 million more years. “It would be simply impossible to recover them,” says Goodman. Instead, the model means that to achieve a similar level of evolutionary complexity, whatever those new species might look like, would take 23 million years.

Luis Valente, the study’s corresponding author, says he was surprised by this finding. “It is much longer than what previous studies have found on other islands, such as New Zealand or the Caribbean,” says Valente, a biologist at the Naturalis Biodiversity Center and the University of Groningen in the Netherlands. “It was already known that Madagascar was a hotspot of biodiversity, but this new research puts into context just how valuable this diversity is. These findings underline the potential gains of the conservation of nature on Madagascar from a novel evolutionary perspective.”

According to Goodman, Madagascar is at a tipping point for protecting its biodiversity. “There is still a chance to fix things, but basically, we have about five years to really advance the conservation of Madagascar’s forests and the organisms that those forests hold,” he says.

This urgent conservation work is made difficult by inequality and political corruption that keeps land-use decisions out of the hands of most Malagasy people, says Goodman: “Madagascar’s biological crisis has nothing to do with biology. It has to do with socio-economics.” But while the situation is dire, he says, “we can't throw in the towel. We’re obliged to advance this cause as much as we can and try to make the world understand that it’s now or never.”

The critically endangered Verreaux’s Sifaka is one of the 109 species of lemurs that currently are extant on Madagascar. A total of 17 species of lemurs have already gone extinct.

CREDIT