Tag: fat

Chemists develop foolproof new test to track the fats we eat

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Philip Britz-McKibbin, Professor of Chemistry & Chemical Biology, McMaster University Credit: JD Howell, McMaster University

A team of researchers at McMaster University has developed a reliable and accurate blood test to track individual fat intake, a tool that could guide public health policy on healthy eating.

Establishing reliable guidelines has been a significant challenge for nutritional epidemiologists until now, because they have to rely on study participants faithfully recording their own consumption, creating results that are prone to human error and selective reporting, particularly when in the case of high-fat diets.

For the study, published in the Journal of Lipid Research, chemists developed a test, which detects specific non-esterified fatty acids (NEFAs), a type of circulating free fatty acid that can be measured using a small volume of blood sample.

“Epidemiologists need better ways to reliably assess dietary intake when developing nutritional recommendations,” says Philip Britz-McKibbin, professor in the Department of Chemistry & Chemical Biology at McMaster University and lead author of the study.

“The food we consume is highly complex and difficult to measure when relying on self-reporting or memory recall, particularly in the case of dietary fats. There are thousands of chemicals that we are exposed to in foods, both processed and natural,” he says.

The study was a combination of two research projects Britz-McKibbin conducted with Sonia Anand in the Department of Medicine and Stuart Phillips in the Department of Kinesiology.

Researchers first assessed the habitual diet of pregnant women in their second trimester, an important development stage for the fetus. The women, some of whom were taking omega-3 fish oil supplements, were asked to report on their average consumption of oily fish and full-fat dairy and were then tested with the new technology. Their study also monitored changes in omega-3 NEFAs in women following high-dose omega-3 fish oil supplementation as compared to a placebo.

Researchers were able to prove that certain blood NEFAs closely matched the diets and/or supplements the women had reported, suggesting the dietary biomarkers may serve as an objective tool for assessment of fat intake.

“Fat intake is among the most controversial aspects of nutritional public health policies given previously flawed low-fat diet recommendations, and the growing popularity of low-carb/high-fat ketogenic based diets” says Britz-McKibbin. “If we can measure it reliably, we can begin to study such questions as: Should pregnant women take fish oil? Are women deficient in certain dietary fats? Does a certain diet or supplement lead to better health outcomes for their babies?”

Researchers plan to study what impact NEFAs and other metabolites associated with dietary exposures during pregnancy, might have on childhood health outcomes in relation to the obesity, metabolic syndrome and chronic disease risk later in life.

https://medicalxpress.com/news/2020-05-chemists-foolproof-track-fats.html

Exercising Before Eating Burns More Fat

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Exercising before breakfast may have more health benefits than waiting until after the meal to get moving, according to a study published in the Journal of Clinical Endocrinology & Metabolism in October.

Researchers led by Javier Gonzalez, a physiologist at the University of Bath in England, conducted the study on a group of 30 overweight, sedentary men. One group drank a carbohydrate-laden vanilla shake for breakfast two hours before moderate cycling, while another group drank it after the same exercise. Both groups exercised three times per week. A third group was given the carb-rich drink but did not work out.

While riders in both cycling groups burned about the same number of calories each time they exercised, those in the group that worked out before drinking the shake burned about twice as many calories from fat per ride as the ones who had the shake beforehand. After the six-week study, members of the exercise-before-meal group also had improved insulin sensitivity, which lowers the risk of diabetes. People in both exercise groups had improved cardiorespiratory fitness compared to those who did not cycle, according to the study.

Exercising before breakfast may have burned more fat because fatty acids can fuel cells if glucose isn’t available, such as after a time of fasting when blood sugar is low, according to Runner’s World. While exercising before breakfast takes advantage of overnight fasting, similar results might be possible by abstaining from food at another time. “We believe that the key is the fasting period, rather than the time of day,” Gonzalez tells The New York Times.

Emily Makowski is an intern at The Scientist. Email her at emakowski@the-scientist.com.

https://www.the-scientist.com/news-opinion/exercising-before-eating-burns-more-fat–study-66789?utm_campaign=TS_DAILY%20NEWSLETTER_2019&utm_source=hs_email&utm_medium=email&utm_content=80070748&_hsenc=p2ANqtz-_mk5jB1Vyqx3xPsKPzk1WcGdxEqSmuirpfpluu4Opm4tMO6n7rXROJrCvQp0yKBw2eCo4R4TZ422Hk6FcfJ7tDWkMpyg&_hsmi=80070748

An explanation of blood sugar

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By Alina Bradford

Blood sugar, or glucose, is the main sugar found in blood. The body gets glucose from the food we eat. This sugar is an important source of energy and provides nutrients to the body’s organs, muscles and nervous system. The absorption, storage and production of glucose is regulated constantly by complex processes involving the small intestine, liver and pancreas.

Glucose enters the bloodstream after a person has eaten carbohydrates. The endocrine system helps keep the bloodstream’s glucose levels in check using the pancreas. This organ produces the hormone insulin, releasing it after a person consumes protein or carbohydrates. The insulin sends excess glucose in the liver as glycogen.

The pancreas also produces a hormone called glucagon, which does the opposite of insulin, raising blood sugar levels when needed. The two hormones work together to keep glucose balanced.

When the body needs more sugar in the blood, the glucagon signals the liver to turn the glycogen back into glucose and release it into the bloodstream. This process is called glycogenolysis.

When there isn’t enough sugar to go around, the liver hoards the resource for the parts of the body that need it, including the brain, red blood cells and parts of the kidney. For the rest of the body, the liver makes ketones , which breaks down fat to use as fuel. The process of turning fat into ketones is called ketogenesis. The liver can also make sugar out of other things in the body, like amino acids, waste products and fat byproducts.

Glucose vs. dextrose
Dextrose is also a sugar. It’s chemically identical to glucose but is made from corn and rice, according to Healthline. It is often used as a sweetener in baking products and in processed foods. Dextrose also has medicinal purposes. It is dissolved in solutions that are given intravenously to increase a person’s blood sugar levels.

Normal blood sugar
For most people, 80 to 99 milligrams of sugar per deciliter before a meal and 80 to 140 mg/dl after a meal is normal. The American Diabetes Association says that most nonpregnant adults with diabetes should have 80 to 130 mg/dl before a meal and less than 180 mg/dl at 1 to 2 hours after beginning the meal.

These variations in blood-sugar levels, both before and after meals, reflect the way that the body absorbs and stores glucose. After you eat, your body breaks down the carbohydrates in food into smaller parts, including glucose, which the small intestine can absorb.

Problems
Diabetes happens when the body lacks insulin or because the body is not working effectively, according to Dr. Jennifer Loh, chief of the department of endocrinology for Kaiser Permanente in Hawaii. The disorder can be linked to many causes, including obesity, diet and family history, said Dr. Alyson Myers of Northwell Health in New York.

“To diagnose diabetes, we do an oral glucose-tolerance test with fasting,” Myers said.

Cells may develop a tolerance to insulin, making it necessary for the pancreas to produce and release more insulin to lower your blood sugar levels by the required amount. Eventually, the body can fail to produce enough insulin to keep up with the sugar coming into the body.

It can take decades to diagnose high blood-sugar levels, though. This may happen because the pancreas is so good at its job that a doctor can continue to get normal blood-glucose readings while insulin tolerance continues to increase, said Joy Stephenson-Laws, founder of Proactive Health Labs (pH Labs), a nonprofit that provides health care education and tools. She also wrote “Minerals – The Forgotten Nutrient: Your Secret Weapon for Getting and Staying Healthy” (Proactive Health Labs, 2016).

Health professionals can check blood sugar levels with an A1C test, which is a blood test for type 2 diabetes and prediabetes, according to the U.S. National Library of Medicine. This test measures your average blood glucose, or blood sugar, level over the previous three months.

Doctors may use the A1C alone or in combination with other diabetes tests to make a diagnosis. They also use the A1C to see how well you are managing your diabetes. This test is different from the blood sugar checks that people with diabetes do for themselves every day.

In the condition called hypoglycemia, the body fails to produce enough sugar. People with this disorder need treatment when blood sugar drops to 70 mg/dL or below. According to the Mayo Clinic, symptoms of hypoglycemia can be:

Tingling sensation around the mouth
Shakiness
Sweating
An irregular heart rhythm
Fatigue
Pale skin
Crying out during sleep
Anxiety
Hunger
Irritability


Keeping blood sugar in control

Stephenson-Laws said healthy individuals can keep their blood sugar at the appropriate levels using the following methods:

Maintaining a healthy weight

Talk with a competent health care professional about what an ideal weight for you should be before starting any kind of weight loss program.

Improving diet

Look for and select whole, unprocessed foods, like fruits and vegetables, instead of highly processed or prepared foods. Foods that have a lot of simple carbohydrates, like cookies and crackers, that your body can digest quickly tend to spike insulin levels and put additional stress on the pancreas. Also, avoid saturated fats and instead opt for unsaturated fats and high-fiber foods. Consider adding nuts, vegetables, herbs and spices to your diet.

Getting physical

A brisk walk for 30 minutes a day can greatly reduce blood sugar levels and increase insulin sensitivity.

Getting mineral levels checked

Research also shows that magnesium plays a vital role in helping insulin do its job. So, in addition to the other health benefits it provides, an adequate magnesium level can also reduce the chances of becoming insulin-tolerant.

Get insulin levels checked

Many doctors simply test for blood sugar and perform an A1C test, which primarily detects prediabetes or type 2 diabetes. Make sure you also get insulin checks.

https://www.livescience.com/62673-what-is-blood-sugar.html#?utm_source=ls-newsletter&utm_medium=email&utm_campaign=05272018-ls

How brown fat keeps us warm

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Adipose Connective Tissue Stores Fat in Our Body. Credit: Berkshire Community College Bioscience Image Library

A new technique to study fat stores in the body could aid efforts to find treatments to tackle obesity.

The approach focuses on energy-burning tissues found deep inside the body – called brown fat – that help to keep us warm when temperatures drop.

Experts are aiming to find it this calorie-burning power can be harnessed to stop weight gain, but little is known about how the process works.

Previous studies have mainly relied on a medical imaging technique called PET/CT to watch brown fat in action deep inside the body. But the method is unable to directly measure the chemical factors in the tissue.

Scientists at the University of Edinburgh developed a technique called microdialysis to measure how brown fat generates heat in people.

The approach involves inserting a small tube into an area of brown fat in the body and flushing it with fluid to collect a snapshot of the tissues’ chemical make-up.

The team tested the technique in six healthy volunteers, using PET/CT to guide the tube to the right location.

They discovered that in cold conditions, brown fat uses its own energy stores and other substances to generate heat.

Brown fat was active under warm conditions too, when the body does not need to generate its own heat, an outcome that had not been seen before.

Researchers hope the technique will help them to analyse the specific chemicals involved, so that they can better understand how brown fat works.

Most of the fat in our body is white fat, which is found under the skin and surrounding internal organs. It stores excess energy when we consume more calories than we burn.

Brown fat is mainly found in babies and helps them to stay warm. Levels can decrease with age but adults can still have substantial amounts of it, mainly in the neck and upper back region. People who are lean tend to have more brown fat.

The study, published in Cell Metabolism, was funded by the Medical Research Council and Wellcome.

Lead researcher Dr Roland Stimson, of the British Heart Foundation Centre for Cardiovascular Science at the University of Edinburgh, said: “Understanding how brown fat is activated could reveal potential targets for therapies that boost its energy-burning power, which could help with weight loss.”

This article has been republished from materials provided by the University of Edinburgh. Note: material may have been edited for length and content. For further information, please contact the cited source.

Reference: Weir, G., Ramage, L. E., Akyol, M., Rhodes, J. K., Kyle, C. J., Fletcher, A. M., … Stimson, R. H. (2018). Substantial Metabolic Activity of Human Brown Adipose Tissue during Warm Conditions and Cold-Induced Lipolysis of Local Triglycerides. Cell Metabolism, 0(0). https://doi.org/10.1016/j.cmet.2018.04.020

https://www.technologynetworks.com/proteomics/news/how-brown-fat-keeps-us-warm-304351?utm_campaign=Newsletter_TN_BreakingScienceNews&utm_source=hs_email&utm_medium=email&utm_content=63228690&_hsenc=p2ANqtz-9oqDIw3te1NPoj51s94kxnA1ClK8Oiecfela6I4WiITEbm_-SWdmw6pjMTwm2YP24gqSzRaBvUK1kkb2kZEJKPcL5JtQ&_hsmi=63228690

‘Fat-clogged’ Immune Cells Fail to Fight Tumors

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by Laura Elizabeth Lansdowne

Researchers have gained a new understanding of the link between obesity and cancer. In the presence of excess fat, the immune surveillance system fails due to an obesity-fueled lipid accumulation in natural killer (NK) cells, preventing their cellular metabolism and trafficking. The new findings were published in Nature Immunology.1

More than 1.9 billion adults are either overweight or obese and a growing amount of evidence proposes that numerous cancer types (including liver, kidney, endometrial and pancreatic cancers)2 are more common in overweight or obese people. Cancer risk is increased in those with higher body fat, with up to 49% of certain types attributed to obesity.3

Previous findings from the GLOBOCAN project indicate that, in 2012 in the United States, approximately 28,000 new cases of cancer in men and approximately 72,000 in women were associated with being obese or overweight.4

The 2018 study1 investigated the effect of obesity on the cellular metabolism, gene expression, and function of NK cells, and its influence on cancer development.

NK cells are cells of the innate immune system that limit the spread of tumors – numerous in vitro models have shown that tumor cells are recognized as ‘targets’ by NK cells.5 These cells destroy their targets by secreting lytic granules containing perforin and apoptosis-inducing granzymes. NK cells require a greater amount of energy to support their anti-tumor activity, therefore they switch their metabolic activity from oxidative phosphorylation (OXPHOS) to glycolysis to meet the increased demand for ATP.1

The researchers discovered that NK cells in an ‘obese environment’ display increased lipid accumulation which affects their cellular bioenergetics, resulting in ‘metabolic paralysis’. This lipid-induced metabolic paralysis led to loss of anti-tumor activity both in vitro and in vivo models. They were able to mimic obesity through fatty-acid administration and by using PPARα/δ agonists, which inhibited mechanistic target of rapamycin (mTOR)-mediated glycolysis.1

However, the researchers also discovered that it was possible to reverse the metabolic paralysis by either inhibiting PPARα/δ or by blocking lipid transport, suggesting that metabolic reprogramming of NK cells could restore their anti-tumor activity in human obesity.1

Corresponding author of the study, Lydia Lynch commented on the importance of the findings in a recent press release: “Despite increased public awareness, the prevalence of obesity and related diseases continue. Therefore, there is increased urgency to understand the pathways whereby obesity causes cancer and leads to other diseases, and to develop new strategies to prevent their progression.”

References

1. Michelet, X., et al. Metabolic reprogramming of natural killer cells in obesity limits antitumor responses. Nature Immunology. (2018) https://www.nature.com/articles/s41590-018-0251-7
2. Mason, L. E., The Link Between Cancer and Obesity. Technology Networks. Available at: https://www.technologynetworks.com/cancer-research/articles/the-link-between-cancer-and-obesity-298207. Accessed: November 12, 2018
3. Renehan, A. G., et al. Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies. Lancet. (2008) 371, 569–578
4. Arnold, M., et al. Global burden of cancer attributable to high body-mass index in 2012: a population-based study. Lancet Oncol. (2015) 16(1): 36–46
5. Vivier, E., et al. Functions of natural killer cells. Nature Immunology. (2008) 9, 503–510

https://www.technologynetworks.com/cancer-research/news/obesity-and-cancer-fat-clogged-immune-cells-fail-to-fight-tumors-311744?utm_campaign=NEWSLETTER_TN_Breaking%20Science%20News&utm_source=hs_email&utm_medium=email&utm_content=68543465&_hsenc=p2ANqtz–8ZbNt7sDLF6bujB3qX9CeJA-hpSQwPHeSLoR5Ju1WYXA6SnOEepdO0o-J7qw_1aGB3nfwldpf30hV3pAvVi7SzJa8fw&_hsmi=68543465

Copper discovered to be key component of burning fat

On By A.P.In metabolismLeave a comment


A fluorescent probe creates a heat map of copper in white fat cells. Higher levels of copper are shown in yellow and red. The left panel shows normal levels of copper from fat cells of control mice, and the right panel shows cells deficient in copper.
Credit: Lakshmi Krishnamoorthy and Joseph Cotruvo Jr./UC Berkeley

A new study is further burnishing copper’s reputation as an essential nutrient for human physiology. A research team led by a scientist at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and at the University of California, Berkeley, has found that copper plays a key role in metabolizing fat.

Long prized as a malleable, conductive metal used in cookware, electronics, jewelry and plumbing, copper has been gaining increasing attention over the past decade for its role in certain biological functions. It has been known that copper is needed to form red blood cells, absorb iron, develop connective tissue and support the immune system.

The new findings, to appear in the July print issue of Nature Chemical Biology but published online today, establishes for the first time copper’s role in fat metabolism.

The team of researchers was led by Chris Chang, a faculty scientist at Berkeley Lab’s Chemical Sciences Division, a UC Berkeley professor of chemistry and a Howard Hughes Medical Institute investigator. Co-lead authors of the study are Lakshmi Krishnamoorthy and Joseph Cotruvo Jr, both UC Berkeley postdoctoral researchers in chemistry with affiliations at Berkeley Lab.

“We find that copper is essential for breaking down fat cells so that they can be used for energy,” said Chang. “It acts as a regulator. The more copper there is, the more the fat is broken down. We think it would be worthwhile to study whether a deficiency in this nutrient could be linked to obesity and obesity-related diseases.”

Dietary copper

Chang said that copper could potentially play a role in restoring a natural way to burn fat. The nutrient is plentiful in foods such as oysters and other shellfish, leafy greens, mushrooms, seeds, nuts and beans.

According to the Food and Nutrition Board of the Institute of Medicine, an adult’s estimated average dietary requirement for copper is about 700 micrograms per day. The Food and Nutrition Board also found that only 25 percent of the U.S. population gets enough copper daily.

“Copper is not something the body can make, so we need to get it through our diet,” said Chang. “The typical American diet, however, doesn’t include many green leafy vegetables. Asian diets, for example, have more foods rich in copper.”

But Chang cautions against ingesting copper supplements as a result of these study results. Too much copper can lead to imbalances with other essential minerals, including zinc.

Copper as a ‘brake on a brake’

The researchers made the copper-fat link using mice with a genetic mutation that causes the accumulation of copper in the liver. Notably, these mice have larger than average deposits of fat compared with normal mice.

The inherited condition, known as Wilson’s disease, also occurs in humans and is potentially fatal if left untreated.

Analysis of the mice with Wilson’s disease revealed that the abnormal buildup of copper was accompanied by lower than normal lipid levels in the liver compared with control groups of mice. The researchers also found that the white adipose tissue, or white fat, of the mice with Wilson’s disease had lower levels of copper compared with the control mice and correspondingly higher levels of fat deposits.

They then treated the Wilson’s disease mice with isoproterenol, a beta agonist known to induce lipolysis, the breakdown of fat into fatty acids, through the cyclic adenosine monophosphate (cAMP) signaling pathway. They noted that the mice with Wilson’s disease exhibited less fat-breakdown activity compared with control mice.

The results prompted the researchers to conduct cell culture analyses to clarify the mechanism by which copper influences lipolysis. The researchers used inductively coupled plasma mass spectroscopy (ICP-MS) equipment at Berkeley Lab to measure levels of copper in fat tissue.

“It had been noted in cattle that levels of copper in the feed would affect how fatty the meat was,” said Chang. “This effect on fat deposits in animals was in the agricultural literature, but it hadn’t been clear what the biochemical mechanisms were linking copper and fat.”

The new work builds upon prior research from Chang’s lab on the roles of copper and other metals in neuroscience. In support of President Barack Obama’s BRAIN Initiative, Berkeley Lab provided Chang seed funding in 2013 through the Laboratory Directed Research and Development program. Chang’s work continued through the BRAIN Tri-Institutional Partnership, an alliance with Berkeley Lab, UC Berkeley and UC San Francisco.

Of the copper in human bodies, there are particularly high concentrations found in the brain. Recent studies, including those led by Chang, have found that copper helps brain cells communicate with each other by acting as a brake when it is time for neural signals to stop.

While Chang’s initial focus was on the role of copper in neural communications, he branched out to investigations of metals in fat metabolism and other biological pathways. This latest work was primarily funded by the National Institutes of Health.

https://www.sciencedaily.com/releases/2016/06/160606200439.htm

They found that copper binds to phosphodiesterase 3, or PDE3, an enzyme that binds to cAMP, halting cAMP’s ability to facilitate the breakdown of fat.

“When copper binds phosphodiesterase, it’s like a brake on a brake,” said Chang. “That’s why copper has a positive correlation with lipolysis.”

Hints from cows

The connection between copper and fat metabolism is not altogether surprising. The researchers actually found hints of the link in the field of animal husbandry.

Discovery of fat breakdown trigger opens door for new obesity treatments

On By A.P.In brain, Medicine, metabolism, ObesityLeave a comment

While it’s known that the brain is responsible for instructing our fat stores to break down and release energy as we need it, scientists haven’t yet been able to pin down exactly how this process plays out. Leptin, a hormone produced by our fat cells, travels to the brain to regulate appetite, metabolism and energy, but it hasn’t been clear what communication was coming back the other way. New research has now uncovered this missing link for the first time, revealing a set of nerves that connect with fat tissue to stimulate the process in a development that could lead to new types of anti-obesity treatments.

The leptin hormone was identified around 20 years ago as a regulator of the body’s metabolism. Low levels of the hormone serve to boost one’s appetite and slow metabolism, while conversely, high leptin levels dull the appetite and facilitate better fat breakdown. Using a combination of techniques, a research team led by Ana Domingos from Portugal’s Instituto Gulbenkian de Ciência were able to shed light on how leptin behaves when sending signals back to the fat by finding the nerves that meet with white fat tissue to prompt its breakdown.

“We dissected these nerve fibers from mouse fat, and using molecular markers identified these as sympathetic neurons,” explains Domingos. “When we used an ultra sensitive imaging technique, on the intact white fat tissue of a living mouse, we observed that fat cells can be encapsulated by these sympathetic neural terminals.”

But to determine the extent of these neurons’ role in obesity, the team carried out further research on mice. The rodents were genetically engineered so that these neurons could be switched on and off through optogenetics, where brain cells are made to behave differently by exposing them to light. Optogenetics is an emerging technique we have seen explored as a means of treating blindness and altering our pain threshold, among other things.

Domingos’ team found that flicking the switch on the neurons locally triggered the release of a neurotransmitter called norepinephrine, which in turn flooded the fat cells with signals that brought about fat breakdown. The team report that without these sympathetic neurons, leptin was not able to stimulate fat breakdown on its own. Therefore the findings suggest that these sympathetic neurons offer a potential target for obesity treatments other than leptin, which the brains of many obese people have a resistance to.

“This result provides new hopes for treating central leptin resistance, a condition in which the brains of obese people are insensitive to leptin,” says Domingos.

The team’s research was published in the journal Cell.

http://www.gizmag.com/neural-mechanism-fat-breakdown-anti-obesity-therapies/39601/

New research shows that high salt diet suppresses weight gain in mice on a high fat diet

On By A.P.In cardiovascular disease, diet, Iowa, Iowa City, MedicineLeave a comment


Dr. Justin Grobe, PhD


Dr. Michael Lutter, MD PhD

In a study that seems to defy conventional dietary wisdom, University of Iowa scientists have found that adding high salt to a high-fat diet actually prevents weight gain in mice.

As exciting as this may sound to fast food lovers, the researchers caution that very high levels of dietary salt are associated with increased risk for cardiovascular disease in humans. Rather than suggest that a high salt diet is suddenly a good thing, the researchers say these findings really point to the profound effect non-caloric dietary nutrients can have on energy balance and weight gain.

“People focus on how much fat or sugar is in the food they eat, but [in our experiments] something that has nothing to do with caloric content – sodium – has an even bigger effect on weight gain,” say Justin Grobe, PhD, assistant professor of pharmacology at the UI Carver College of Medicine and co-senior author of the study, which was published in the journal Scientific Reports on June 11.

The UI team started the study with the hypothesis that fat and salt, both being tasty to humans, would act together to increase food consumption and promote weight gain. They tested the idea by feeding groups of mice different diets: normal chow or high-fat chow with varying levels of salt (0.25 to 4 percent). To their surprise, the mice on the high-fat diet with the lowest salt gained the most weight, about 15 grams over 16 weeks, while animals on the high-fat, highest salt diet had low weight gain that was similar to the chow-fed mice, about 5 grams.

“We found out that our ‘french fry’ hypothesis was perfectly wrong,” says Grobe, who also is a member of the Fraternal Order of Eagles Diabetes Research Center at the UI and a Fellow of the American Heart Association. “The findings also suggest that public health efforts to continue lowering sodium intake may have unexpected and unintended consequences.”

To investigate why the high salt prevented weight gain, the researchers examined four key factors that influence energy balance in animals. On the energy input side, they ruled out changes in feeding behavior – all the mice ate the same amount of calories regardless of the salt content in their diet. On the energy output side, there was no difference in resting metabolism or physical activity between the mice on different diets. In contrast, varying levels of salt had a significant effect on digestive efficiency – the amount of fat from the diet that is absorbed by the body.

“Our study shows that not all calories are created equal,” says Michael Lutter, MD, PhD, co-senior study author and UI assistant professor of psychiatry. “Our findings, in conjunction with other studies, are showing that there is a wide range of dietary efficiency, or absorption of calories, in the populations, and that may contribute to resistance or sensitivity to weight gain.”

“This suppression of weight gain with increased sodium was due entirely to a reduced efficiency of the digestive tract to extract calories from the food that was consumed,” explains Grobe.

It’s possible that this finding explains the well-known digestive ill effects of certain fast foods that are high in both fat and salt, he adds.

Through his research on hypertension, Grobe knew that salt levels affect the activity of an enzyme called renin, which is a component in the renin- angiotensin system, a hormone system commonly targeted clinically to treat various cardiovascular diseases. The new study shows that angiotensin mediates the control of digestive efficiency by dietary sodium.

The clinical usefulness of reducing digestive efficiency for treating obesity has been proven by the drug orlistat, which is sold over-the-counter as Alli. The discovery that modulating the renin-angiotensin system also reduces digestive efficiency may lead to the developments of new anti-obesity treatments.

Lutter, who also is an eating disorders specialist with UI Health Care, notes that another big implication of the findings is that we are just starting to understand complex interactions between nutrients and how they affect calorie absorption, and it is important for scientists investigating the health effects of diet to analyze diets that are more complex than those currently used in animal experiments and more accurately reflect normal eating behavior.

“Most importantly, these findings support continued and nuanced discussions of public policies regarding dietary nutrient recommendations,” Grobe adds.

http://www.eurekalert.org/pub_releases/2015-06/uoih-hsp061115.php