Study: Fat Accumulates in the Lungs of Overweight and Obese People

Researchers have shown for the first time that fatty tissue accumulates in the airway walls, particularly in people who are overweight or obese.

Scientists already know that people who are overweight or obese are more likely to suffer with wheezing and asthma, but the reasons for this have not been completely explained.

The new study, published in the European Respiratory Journal, suggests that this fatty tissue alters the structure of people’s airways and this could be one reason behind the increased risk of asthma.

The study’s author is Mr John Elliot, a senior research officer at Sir Charles Gairdner Hospital in Perth, Western Australia. He said: “Our research team studies the structure of the airways within our lungs and how these are altered in people with respiratory disease.

“Looking at samples of lung, we spotted fatty tissue that had built up in the airway walls. We wanted to see if this accumulation was correlated with body weight.”

The researchers examined post-mortem samples of lung that had been donated for research and stored in the Airway Tissue Biobank. They studied samples from 52 people, including 15 who had no reported asthma, 21 who had asthma but died of other causes and 16 who died of asthma.

Using dyes to help visualise the structures of 1373 airways under a microscope, they identified and quantified any fatty tissue present. They compared this data with each person’s body mass index (BMI).

For the first time, the study showed that fatty tissue accumulates in the walls of the airways. The analysis revealed that the amount of fat present increases in line with increasing BMI. The research also suggests that this increase in fat alters the normal structure of the airways and leads to inflammation in the lungs.

Co-author, Dr Peter Noble, an associate professor at the University of Western Australia in Perth said: “Being overweight or obese has already been linked to having asthma or having worse asthma symptoms. Researchers have suggested that the link might be explained by the direct pressure of excess weight on the lungs or by a general increase in inflammation created by excess weight.

“This study suggests that another mechanism is also at play. We’ve found that excess fat accumulates in the airway walls where it takes up space and seems to increase inflammation within the lungs. We think this is causing a thickening of the airways that limits the flow of air in and out of the lungs, and that could at least partly explain an increase in asthma symptoms.”

The team are looking for new ways to study and measure fatty tissue in the lungs. They want to confirm the relationship with respiratory disease and to find out whether the effect can be reversed by weight loss therapy.

Professor Thierry Troosters is President of the European Respiratory Society and was not involved in the study. He said: “This is an important finding on the relationship between body weight and respiratory disease because it shows how being overweight or obese might be making symptoms worse for people with asthma. This goes beyond the simple observation that patients with obesity need to breathe more with activity and exercise hence adding to their ventilatory burden. The observation points at true airway changes that are associated with obesity.

“We need to investigate this finding in more detail and particularly whether this phenomenon can be reversed with weight loss. In the meantime, we should support asthma patients to help them achieve or maintain a healthy weight.”

Source: European Respiratory Society

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Drinking Soda While Eating Burger Is Especially Fattening

Dennis Thompson wrote . . . . . .

Combining a sugary soda with your burger or fried chicken can really prime your body to pack on more pounds, a new study suggests.

Folks who had a sweetened drink with a high-protein meal stored more unused fat, compared to others who ate the same food with a sugar-free beverage, laboratory tests revealed.

Their bodies did not burn about a third of the additional calories provided by the sugary drink, researchers found.

The participants also burned less fat from their food, and it took less energy overall to digest the meal.

“If we are adding extra carbohydrates on top of what’s already in a meal, that will definitely have an effect on the body being able to use fat as an energy source, and it will more than likely go into energy storage,” said lead researcher Shanon Casperson. She’s a research biologist with the U.S. Department of Agriculture.

Sodas, sweetened coffee and iced tea drinks, fruit drinks, energy beverages and the like are leading sources of added sugar in the American diet, according to the U.S. Centers for Disease Control and Prevention. Six in 10 kids and half of adults drink at least one sugary beverage each day.

Food contains three major types of nutrients — carbohydrates, fats and protein. Casperson and her team wanted to see how extra carbs in the form of a sugary drink would affect metabolism of fats and proteins.

For the study, 27 healthy-weight adults were placed in a sealed “metabolic room” that carefully tracked how much oxygen was inhaled and carbon dioxide was exhaled, Casperson said. Urine samples were also collected.

“With those three variables, we are able to calculate the amount of nutrients they use” as well as the calories they burn every minute, Casperson said.

Participants spent two full days in the sealed room. On one day they ate two meals containing 15 percent protein, and on the other they ate two meals with 30 percent protein. The meals consisted of bread, ham, cheese, potatoes and butter, and each provided 17 grams of fat and 500 calories.

Each day, the participants had a sugary cherry-flavored drink with one meal and a sugar-free cherry drink with the other meal, Casperson said.

The sugar-sweetened drink decreased fat oxidation — the process that kick-starts the breakdown of fat molecules — by 8 percent, the researchers discovered.

Also, the sweetened drink consumed with a 15 percent protein meal decreased fat oxidation by an average 7.2 grams, while the same sugary drink with a 30 percent protein meal decreased fat oxidation by 12.6 grams.

The researchers think the extra load of carbohydrates in a soda might reduce the body’s need to process dietary fat for energy, since fat is more difficult to burn than sugar.

“It’s easier for the body to use carbohydrates as an energy source,” Casperson said. “When you provide the body with carbohydrates, it’s going to use that first.” Unburned fat then winds up deposited somewhere in a person’s body, such as the belly or hips.

The study provides much-needed nuance to the understanding of fast-food nutrition, said Erika Renick. She’s a bariatric dietitian with the Comprehensive Weight Loss Center at Staten Island University Hospital in New York City.

“While this was a small sample size, the study backs up what recent research has been pointing to — that adding protein to meals helps to keep us full and that sugary drinks can influence our food cravings,” Renick said.

“However, this study takes it a step further by suggesting that pairing sugar-sweetened drinks with protein-rich meals can encourage weight gain more than we originally understood,” Renick continued.

“This specific combination seems to decrease how well our bodies burn fat,” she said. “More research would need to be done, but steering people away from this combination could potentially be another tool when counseling people on weight management.”

Casperson isn’t sure why adding extra protein to a meal seemed to affect the reduction in fat burning. “That’s something we need to look at in future research,” she said.

The study appears in the journal BMC Nutrition.

Source: HealthDay


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Replacing Saturated Fat with Healthier Fat May Lower Cholesterol in Healthy Diet

The American Heart Association continues to recommend replacing saturated fats with poly- and mono-unsaturated vegetable oil to help prevent heart disease, according to a new American Heart Association advisory, published in the association’s journal Circulation.

Periodically, the evidence supporting limiting saturated fats has been questioned in scientific literature and the popular press. This advisory was commissioned to review the current evidence and explain the scientific framework behind the American Heart Association’s long-standing recommendation to limit foods high in saturated fats.

“We want to set the record straight on why well-conducted scientific research overwhelmingly supports limiting saturated fat in the diet to prevent diseases of the heart and blood vessels,” said Frank Sacks, M.D., lead author of the advisory and professor of Cardiovascular Disease Prevention at the Harvard T.H. Chan School of Public Health in Boston, Massachusetts. “Saturated fat increases LDL – bad cholesterol – which is a major cause of artery-clogging plaque and cardiovascular disease.”

Saturated fats are found in meat, full-fat dairy products and tropical oils such as coconut, palm and others. Other types of fats include poly-unsaturated fats, found in corn, soybean, peanut and other oils, and mono-unsaturated fats, found in olive, canola, safflower, avocado and other oils. The advisory reports that:

  • Randomized controlled trials that lowered intake of dietary saturated fat and replaced it with polyunsaturated vegetable oil reduced cardiovascular disease by approximately 30 percent –similar to that achieved by cholesterol-lowering drugs, known as statins.
  • Prospective observational studies in many populations showed that lower intake of saturated fat coupled with higher intake of polyunsaturated and monounsaturated fat is associated with lower rates of cardiovascular disease.
  • Several studies found that coconut oil – which is predominantly saturated fat and widely touted as healthy – raised LDL cholesterol in the same way as other saturated fats found in butter, beef fat and palm oil.
  • Replacement of saturated fat with mostly refined carbohydrate and sugars is not associated with lower rates of CVD.

“A healthy diet doesn’t just limit certain unfavorable nutrients, such as saturated fats, that can increase the risk of heart attacks, strokes and other blood vessel diseases. It should also focus on healthy foods rich in nutrients that can help reduce disease risk, like poly- and mono-unsaturated vegetable oils, nuts, fruits, vegetables, whole grains, fish and others,” Sacks said.

Examples of healthy dietary patterns include the Dietary Approaches To Stop Hypertension (DASH) diet and a Mediterranean-style diet, both of which emphasize unsaturated vegetable oils, nuts, fruits, vegetables, low-fat dairy products, whole grains, fish and poultry and limits red meat, as well as foods and drinks high in added sugars and salt.

Source: American Heart Association


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Even One High-Fat Meal Can Harm Your Liver, Study Finds

Eating a high-fat meal — say, a cheeseburger and fries or a pepperoni pizza — disrupts liver function, a new, small study reveals.

Researchers found that the high levels of saturated fat found in such rich foods immediately alter the work of the liver, possibly setting the body up for serious disease down the line.

“The effects mimic the abnormalities seen in people with severe metabolic disease,” said study co-author Dr. Michael Roden, referring to conditions like fatty liver disease and cirrhosis.

“Our findings paint the picture of the earliest changes in liver metabolism leading to fatty liver diseases and liver cirrhosis in the context of obesity and type 2 diabetes,” said Roden. He’s scientific director of the German Diabetes Center at Heinrich Heine University in Dusseldorf.

How long these metabolic alterations last after people indulge in a rich meal isn’t clear.

The liver plays a crucial role in processing the fats and carbohydrates people eat.

In some cases when fatty foods are repeatedly eaten to excess, fats accumulate and cause a condition known as nonalcoholic fatty liver.

This condition has ballooned along with the U.S. obesity epidemic, and is thought to affect as many as 25 percent of people in the United States. It can lead to cirrhosis, a serious condition characterized by scarring of the liver.

Dr. Hannele Yki-Jarvinen is professor of medicine at the University of Helsinki in Finland. “We know diets high in saturated fat make the liver fatty,” she said.

“Saturated fats such as in butter, fatty cheeses and coconut oil are thus the worst thing to eat from the liver perspective,” said Yki-Jarvinen, co-author of a commentary accompanying the new study.

For the study, the researchers assigned 14 healthy, lean young men to consume a placebo or a dose of palm oil that varied according to their weight. The palm oil provided levels of saturated fat equivalent to that from an eight-slice pepperoni pizza or a cheeseburger with large fries, the report said.

This “fat loading” caused the liver to produce 70 percent more glucose, which could boost blood sugar levels over time, Roden said. Potentially, this could contribute to insulin sensitivity — a precursor to type 2 diabetes.

Fat loading also caused liver cells to work harder, which could stress them and contribute to liver disease, he noted.

In addition, the saturated fat lowered the liver’s ability to store glucose compared to fat, “which over time might favor fatty liver diseases,” Roden said.

It’s possible that healthy people could easily overcome these effects while those who repeatedly eat fat-laden foods might be less fortunate, Roden added.

Yki-Jarvinen said that while cirrhosis is difficult to reverse, most people can boost their liver health.

“If you change your diet to a more healthy one containing healthy fats, such as found in olive oil, your liver fat decreases in a few days,” she said.

The study was published in the Journal of Clinical Investigation.

Source: U.S. Department of Health and Human Services


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Higher Consumption of Unsaturated Fats Linked with Lower Mortality

Consuming higher amounts of unsaturated fats was associated with lower mortality, according to a study from Harvard T.H. Chan School of Public Health. In a large study population followed for more than three decades, researchers found that higher consumption of saturated and trans fats was linked with higher mortality compared with the same number of calories from carbohydrates. Most importantly, replacing saturated fats with unsaturated fats conferred substantial health benefits. This study provides further support for the 2015-2020 Dietary Guidelines for Americans that emphasize the types of fat rather than total amount of fat in the diet.

The study is the most detailed and powerful examination to date on how dietary fats impact health. It suggests that replacing saturated fats like butter, lard, and fat in red meat with unsaturated fats from plant-based foods—like olive oil, canola oil, and soybean oil—can confer substantial health benefits and should continue to be a key message in dietary recommendations.

The study will be published online in JAMA Internal Medicine.

“There has been widespread confusion in the biomedical community and the general public in the last couple of years about the health effects of specific types of fat in the diet,” said Dong Wang, a doctoral candidate, SD ’16, in the Departments of Nutrition and Epidemiology at Harvard Chan School and lead author of the study. “This study documents important benefits of unsaturated fats, especially when they replace saturated and trans fats.”

The study included 126,233 participants from two large long-term studies—the Nurses’ Health Study and the Health Professionals Follow-Up Study—who answered survey questions every 2-4 years about their diet, lifestyle, and health for up to 32 years. During the follow-up, 33,304 deaths were documented. Researchers from Harvard Chan School and Brigham and Women’s Hospital examined the relationship between types of fats in the participants’ diets and overall deaths among the group during the study period, as well as deaths due to cardiovascular disease (CVD), cancer, neurodegenerative disease, and respiratory disease.

Different types of dietary fat had different associations with mortality, the researchers found. Trans fats—on their way to being largely phased out of food—had the most significant adverse impact on health. Every 2% higher intake of trans fat was associated with a 16% higher chance of premature death during the study period. Higher consumption of saturated fats was also linked with greater mortality risk. When compared with the same number of calories from carbohydrate, every 5% increase in saturated fat intake was associated with an 8% higher risk of overall mortality.

Conversely, intake of high amounts of unsaturated fats—both polyunsaturated and monounsaturated—was associated with between 11% and 19% lower overall mortality compared with the same number of calories from carbohydrates. Among the polyunsaturated fats, both omega-6, found in most plant oils, and omega-3 fatty acids, found in fish and soy and canola oils, were associated with lower risk of premature death.

The health effects of specific types of fats depended on what people were replacing them with, the researchers found. For example, people who replaced saturated fats with unsaturated fats—especially polyunsaturated fats—had significantly lower risk of death overall during the study period, as well as lower risk of death from CVD, cancer, neurodegenerative disease, and respiratory disease, compared with those who maintained high intakes of saturated fats. The findings for cardiovascular disease are consistent with many earlier studies showing reduced total and LDL (“bad”) cholesterol when unsaturated fats replace trans or saturated fats.

People who replaced saturated fats with carbohydrates had only slightly lower mortality risk. In addition, replacing total fat with carbohydrates was associated with modestly higher mortality. This was not surprising, the authors said, because carbohydrates in the American diet tend to be primarily refined starch and sugar, which have a similar influence on mortality risk as saturated fats.

“Our study shows the importance of eliminating trans fat and replacing saturated fat with unsaturated fats, including both omega-6 and omega-3 polyunsaturated fatty acids. In practice, this can be achieved by replacing animal fats with a variety of liquid vegetable oils,” said senior author Frank Hu, professor of nutrition and epidemiology at Harvard Chan School and professor of medicine at Harvard Medical School.

Source: Harvard T.H. Chan School of Public Heath