Obesity and Diabetes – Is Your Gut in Control?

August 28, 2015 by

Aug. 21, 2015

By Medical Discovery News

Your body is like a forest, providing a home to microscopic flora and fauna. In fact, your body is home to up to 100 times more microbes than your own cells, which make up your microbiome. While we provide them residence, these microbes help us out by providing a first line of defense against disease trying to invade our bodies, even breaking down food during digestion and producing vitamins. Now, the microbes that live in the digestive tract are helping us understand diabetes better.

According to the Human Microbiome Project sponsored by the National Institutes of Health, the microbiome plays a huge role in human health. When the microbiome is altered or imbalanced, it can cause conditions like obesity, irritable bowel syndrome, skin disease, urogenital infection, allergy, and can even affect emotion and behavior.

Recently, scientists from Israel discovered another surprising effect of the microbiome while investigating the use of artificial sweeteners in relation to glucose intolerance and diabetes. Artificial sweeteners such as saccharin, sucralose, and aspartame are commonly used in weight loss strategies because they do not add calories while still satisfying sweet cravings. However, artificial sweeteners are not always effective in managing weight and glucose, and scientists at the Weizmann Institute of Science may have figured out why.

Through experimentation they observed that adding artificial sweeteners to the diets of mice caused significant metabolic changes, including increasing blood sugar levels more than mice fed regular sugar. It didn’t matter whether the mouse was obese or at a normal weight, they all reacted the same. Dietary changes can alter the populations of bacteria in our guts, so the study addressed whether those changes affected blood glucose levels as well. After being treated with saccharin for nine days, the populations of gut bacteria in the mice shifted dramatically and corresponded with an increase in their glycemic index. Specifically, the bacterial group Bacteroidetes increased while the group Clostridiales decreased. These changes in bacterial populations is associated with obesity in mice and people.

When they administered antibiotics to reverse this and return the bacterial populations to a healthy state, it also countered the effects of saccharin, returning glucose levels to normal. To take it a step further, researchers took feces from saccharin-consuming mice showing glucose intolerance and transplanted them into other mice that had never consumed saccharin. Remarkably, those mice started showing signs of glucose intolerance.

In a study of 400 people, those who consumed artificial sweeteners had a gut microbiome that was vastly different from those who did not. They had a group of people consume high levels of artificial sweeteners for seven days, and like the rats their glucose levels increased and their microbiomes changed.

Overall, these studies show that artificial sweeteners may induce glucose intolerance instead of preventing it due to the intimate connection between the bacteria that live in our digestive systems and our metabolic state. In the future, expect to see diagnostic and therapeutic procedures that utilize our microbial friends.

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It’s Not Just Venus or Mars Anymore

December 5, 2014 by

Dec. 5, 2014

By Medical Discovery News

It's Not Just Mars or Venus Anymore

While the gender gaps are closing, sometimes the differences between men and women seem as great as the differences between Venus and Mars. For example, men and women tolerate medications very differently. Due to this, the Food and Drug Administration (FDA) has recently changed the recommended dosage of the sleep aid Lunesta from two milligrams to one milligram because of its prolonged effects on women.

Women reported feeling drowsy in the morning hours after waking, raising concerns about the hazards of driving and working. While men and women are often prescribed the same dosages of medications, this case shows how men and women are not the same organism and drug dosing might need to take that into consideration.

For basic studies in the biomedical laboratory, many cells lines that are used experimentally are derived from tissues obtained from males, either human or animal. Even in the very early steps of identifying a drug and determining how it works, efforts are already focused on those of us with a Y chromosome.

Clinical trials are conducted before a new drug can be approved, and trials also favor males. In fact, white males remain the predominant subjects for drug trials today. Women were initially avoided in clinical trials because of concerns that they were pregnant or would become pregnant. Women also have cyclic hormones that alter metabolism and could interact with drugs. While this is precisely why women’s tolerance of a drug should be tested prior to its approval, researchers thought this complicated the early stages of the process. Once a drug is launched, the number of people using the drug expands and these side effects start to be reported. While an individual physician may notice patients have side effects, they do not have a wide view of the whole population’s reactions.

Pharmokinetics is the study of what happens to drugs administered to a living organism, and could explain some reasons why men and women handle the same medication differently. For starters, men and women have a number of basic physiological differences. Firstly, women tend to have a lower body weight and body volume. Therefore, the concentration of a drug is often higher in a woman. Women also have a lower gastric emptying, slower gastrointestinal motility, and different absorption rate that can alter the amount of a drug that gets to the blood and is distributed throughout the body. They have different glomerular filtration in their kidneys, which reduces the rate at which drugs are cleared out of the body and therefore leads to higher and more prolonged drug levels. Women experience greater sensitivity to beta blockers, which are used to treat heart conditions; opioids, which are used to control pain; and antipsychotics.

The pharmacodynamics (how drugs function) in female and male bodies can be quite different also. Aspirin is a great example. It is less effective at lowering subsequent heart attacks in women when given the standard preventive dose. They may need higher doses to prevent a second cardiovascular episode.

Recently, the National Institutes of Health (NIH) has required that all cell, animal, and human studies it funds have a balanced representation of both genders. While this may increase the cost of developing therapeutics, it will certainly expand our understanding of how medicines affect the genders differently and improve drugs for everyone.

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Baby Bacteria

September 26, 2014 by

Sept. 26, 2014

By Medical Discovery News

Fetus in utero

While we know for sure that the bacteria living in and on us are key to our own well-being, more evidence suggests that we acquire our microbiomes before we’re even born. While a baby does acquire bacterial flora from its mother as it moves through the birth canal, scientists now think that our symbiotic, life-long relationships with bacteria begin in utero long before birth. They found bacteria living in the placenta, an organ previously thought to be sterile. They also discovered a baby’s bacteria to be similar to the bacterial flora of the mother’s mouth, making oral hygiene during pregnancy extra important.

An experiment in 2008 by Spanish scientists indicated that bacteria are acquired in some way before birth. They inoculated pregnant mice with labeled bacteria, which were then found in the meconium, the first bowel movement after birth. This was true even when the babies had been delivered by C-section. So scientists knew then that bacteria are acquired before birth and even without the birth canal, changing what we thought we knew about the womb.

Since then, scientists at Baylor College of Medicine have been studying the inside of the womb and birth canal in both humans and animals. They discovered that the vaginal microbiome changed during pregnancy, but it did not resemble that of newborns. So where did they get their bacteria from?

Baylor scientists then examined placentas from 320 women immediately after birth. Using DNA sequencing, they identified the individual types of bacteria each placenta contained. Comparing them to bacteria growing in and on the mothers, they found that the types of bacteria living in the mothers’ mouths most closely resembled those in their own placentas. Interestingly, the bacteria in the placenta consisted of high proportions of bacteria responsible for synthesizing vitamins and other nutrients, which probably benefits a developing fetus and newborn. So a fetus is first exposed to bacteria from the placenta, then at birth additional bacteria are introduced, and then again when babies are exposed bacteria on their parent’s skin, in breast milk, and in their environment.

Other studies have shown the influence of the microbiome on a mother and her baby. In one experiment, monkeys who ate a high-fat diet while pregnant and lactating produced babies with different proportions of bacteria in their guts than those of monkeys fed a normal diet. The short- and long-term consequences of abnormal maternal and infant microbiomes are not yet known, but it’s speculated that these changes could influence the metabolism of the infant and the development of metabolic disorders.

Science is increasingly aware of the role and importance the microbiome has in various parts of the body and the part it plays in human health and disease.

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Bear-ly Understanding Diabetes

May 30, 2014 by

May 30, 2014

By Medical Discovery News

What can studying grizzly bears reveal about human diabetes?

While they are some of the largest bears on earth, Grizzly bears aren’t usually accused of being fat. Regardless, these animals are helping scientists discover new and better treatments for human obesity and diabetes.

Grizzlies spend the late summers consuming more than 50,000 calories per day. As a comparison, a moderately active 50-year-old human female is recommended 2,300. Grizzlies then hibernate for up to seven months, relying on the pounds of stored fat they accumulated before winter. While hibernating, bears do not eat, urinate, or defecate. 

Scientists wondered if all the weight and fat bears gain results in diabetes like it does in humans. Overweight people face an increased risk of type 2 diabetes, in which the body does not make enough of the hormone insulin or cells do not respond to it. Insulin helps move a type of sugar called glucose from the blood into cells, where it is used for energy and as a precursor for other molecules the body needs. If sugar levels in the blood remain elevated and the body doesn’t have enough insulin, cells are starved for energy, leading to damaged eyes, kidneys, nerves, and hearts. 

Interestingly, Grizzly bears can actually control their insulin responsiveness. When they are the fattest, they are most sensitive to insulin, thereby keeping their blood sugar levels healthy. Soon after going into hibernation, they switch to complete insulin resistance, meaning they develop type 2 diabetes. But unlike humans, their blood sugar levels remain normal. When they awaken in the spring, their insulin responsiveness is restored. Bears do this not so much to regulate their blood sugar levels as to regulate their storage and utilization of fat. So how do bears control their insulin responsiveness? And could it lead to new treatments for type 2 diabetes in humans?

PTEN is a protein that regulates cells’ sensitivity to insulin. Scientists know exactly when Grizzlies increase or decrease PTEN activity, they just don’t know how. People with a PTEN mutation have a metabolism similar to Grizzlies’.  These people have an increased risk of obesity and cancer but a decreased risk of developing type 2 diabetes because they are more sensitive to insulin.

Grizzlies have also evolved to the ability to accumulate large amounts of fat only in their adipose tissue, just below the skin so it doesn’t interfere with the rest of their bodies. In humans, on the other hand, fat can accumulate in many places like the liver, in muscles, and around other internal organs, which are all highly unhealthy places to keep fat. Bears can also have elevated levels of cholesterol without the serious consequences of cardiovascular disease.

During hibernation, the Grizzly bears’ kidneys shut down. But despite the high levels of toxins that accumulate in the blood without working kidneys, they don’t die or even suffer from it like a human would. When they wake up, their kidney function is restored with no permanent damage.

After millions of years of evolution, Grizzly bears and other animals have developed solutions for biological challenges humans still face. Studying them is a new approach that has the potential to create treatments for many human conditions.

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The Trouble with Sugar Substitutes

December 20, 2013 by

Dec. 20, 2013

By Medical Discovery News

Those reaching for a packet of artificial sweetener to satisfy a sweet tooth without adding calories may want to think again – the long-time diet staple may actually lead to serious unintended side effects.

Artificial sweeteners include the recently launched Stevia products like Truvia and the compounds  aspartame (found in Equal), saccharin (Sweet N’ Low), and sucralose (Splenda). These were developed because they add no caloric content to the foods they are added to, but they stimulate the sweet receptors on the tongue. Non-caloric sweeteners are popular with those working to control their weight because of the allure of no calories without sacrificing sweetness.

Consider one product – yogurt. There can be 200 calories or more in those sweetened with sugar while the artificially sweetened varieties come in under 100 calories. The shine of artificial sweeteners may be wearing off though, as some recent studies suggest their use may actually lead to weight gain.

The first sign that artificial sweeteners weren’t as harmless as they seem was a study in the 1970s that linked saccharin to bladder cancer, although those results aren’t substantiated, and approved artificial sweeteners are now considered generally safe for human consumption.

In a new study at Washington University in St. Louis, scientists looked at people with a body mass index (BMI) of over 42 (30 and over is considered obese), who don’t have diabetes and don’t regularly use sweeteners. Individuals were divided into two groups and given the artificial sweetener sucralose or water before ingesting a solution of glucose, the same amount given during a glucose tolerance test. On a separate day, the groups were reversed so researchers could compare the effects in each person.  

The results were surprising. When individuals drank sucralose before ingesting glucose, their insulin levels peaked at a higher level and increased by about 20 percent more than those drinking water alone. This means that sucralose was affecting insulin and blood glucose levels. Previously, scientists thought that these sweeteners did not have an effect on sugar metabolism. 

It turns out that there are sweet responsive receptors in the gut and pancreas that are similar to those found on the human tongue. When they are stimulated, they can cause an increase in the release of hormones including insulin. This in turn causes more sugar to be absorbed in the gut and subsequently higher levels in the blood. For unknown reasons, it happens only in the obese. An elevation in insulin levels can contribute to insulin resistance and type 2 diabetes. 

One thing is for sure – further research will help scientists understand the effects of artificial sweeteners on human metabolism.

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Keeping That Weight Off

February 1, 2013 by

Feb. 1, 2013

By Medical Discovery News

Keep that weight off

Americans don’t lack methods of dieting – South Beach, Atkins, Weight Watchers, Nutrisystem, Slim Fast, detoxing, juice cleanses – but not all are healthy. With public health organizations and the media constantly remarking on the obesity epidemic in the U.S., new studies on approaches to start and maintain weight loss couldn’t come at a better time.

A new study conducted at Boston Children’s Hospital and published in the “Journal of the American Medical Association” compared the weight loss and subsequent weight maintenance of three popular dieting approaches: low carb diets, low fat diets, and low glycemic diets. 

When someone decreases the amount of calories they consume, the body’s metabolism slows, reducing the use of calories and contributing to weight gain. This can work against the goal of losing weight and keeping it off. So researchers examined the affect of these popular dieting approaches on long-term weight loss.

The Boston study followed a group of overweight and obese adults aged 18 to 40 for 10 weeks. After achieving an initial 10 to 15 percent weight loss, researchers placed subjects on one of the three diets and looked for changes in their metabolism and weight maintenance. These diets were isocaloric, meaning all subjects consumed the same number of calories despite being on the different diet plans. 

The low carb diet had the most pronounced affect on metabolism with the best resting energy expenditure (REE) and total energy expenditure (TEE). But the low carb diet also resulted in some undesirable side effects, like high levels of the stress hormone cortisol, which can lead to diabetes, and biochemical markers like CRP, which are associated with inflammation and heart disease.

Similarly, the low fat diet produced the hormone leptin, which is associated with hunger and could lead to weight gain. In contrast, the low glycemic diet allowed stable blood sugar and metabolism levels without elevations in stress hormones and other negative biochemical markers. What type of food a person eats affects their metabolism, and a person’s metabolic index determines how many of those calories will be burned. 

The low glycemic diet derives 40 percent of calories from carbohydrates, 40 percent from fats, and 20 percent from proteins. The diet uses a number of fiber-rich foods like beans, non-starchy vegetables, fruit, and whole grains; lean protein sources like fish and skinless poultry; and healthy fats from nuts, avocados, and certain vegetable oils. These foods require a longer time to digest and absorb, leaving people feeling fuller for a longer time. 

The main conclusion of this study is that a calorie is not just a calorie in the context of weight loss or maintenance. Successful dieting and weight maintenance requires behavioral modifications in addition to caloric restriction, and individuals should consult their physicians about their weight-loss goals and diet plans.

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