The Brain in Your Gut

Relation of human brain and guts, second brain

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Did you know your gut has a brain of its own? It’s called the enteric nervous system. The brain in your gut is embedded in the wall of the digestive tract. Together with your “big brain,” the enteric nervous system helps control gastrointestinal function, including the mixing and grinding of food in the stomach and absorption of nutrients in the intestines.

An adult’s enteric nervous system is made up of 200 to 600 million nerve cells (neurons). That’s as many neurons as are in a cat’s brain or even your spinal cord! The neurons in the enteric nervous system interact with smooth muscle to move food through the digestive system. The brain in your gut also plays an important role in regulating your immune system. It attacks bacteria and viruses (pathogens) that invade the digestive tract by releasing protective substances called peptides that make it harder for pathogens to do harm.

Although the brain in your gut functions independently from the “big brain”—and is the only organ in your body that can do so—normal digestive function requires communication between the enteric nervous system and the brain. The enteric nervous system provides sensory information to the brain to help you decide what, when and how much you eat. When you’re hungry or see something you’re craving (like a piece of chocolate cake or a juicy burger), your brain tells your gut to start the digestion process by producing gastric secretions in the stomach.

Problems with the enteric nervous system can lead to different digestive diseases such as irritable bowel syndrome and functional constipation. Studies have demonstrated that losing some of the neurons in the gut can be a cause of these conditions. Understanding how and why these neurons die is an important topic of research that could result in finding new treatments for digestive diseases.

To learn more about digestive disease, visit the National Institute of Diabetes and Digestive and Kidney Diseases website.

 

Ninotchska DelvalleNinotchska Delvalle is a doctoral candidate in the neuroscience program at Michigan State University. Her research focuses on how specialized cells of the enteric nervous system (enteric glia) contribute to the development of gastrointestinal disease.

Like Father, Like Son (and Daughter): How Your Dad’s Past Affects Your Future

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What makes your father the best dad in the world? Maybe it’s his sense of humor or the times he has taken you to the movies or played catch in the yard. Or maybe it’s the fact that he made healthy lifestyle choices before you were born. Recent research suggests that your father’s health before you were conceived (preconception) may change the way your genes behave to affect your future health. It almost sounds like something out of a science fiction movie, but it’s real.

Studies tend to focus on the mother’s preconception health and the risks her baby might face later in life if she’s overweight. But a dad’s weight and early eating habits can also play a role, according to research published in the American Journal of Stem Cells. Researchers found that offspring of men who were obese before reproducing were more likely to have diabetes and be overweight. On the other hand, the researchers also found that fathers who had limited food resources in their early life caused genetic changes that protected their children—and even grandchildren—against cardiovascular disease.

Most people know that exercise is one of the healthiest lifestyle choices you can make to maintain your weight and keep your heart and even your brain healthy. However, research presented at the APS Integrative Biology of Exercise 7 meeting showed that offspring of men who exercised long term before conceiving had a higher likelihood of being obese and developing diabetes. This result was a huge surprise to the research team, but is it a reason to stop exercising? Not really. The study focused on how efficiently the body used energy on a high-fat diet. Limiting dietary fat and being active is still the way to go for most people.

Keeping stress levels low is also a good plan for dads-to-be. One study suggests that a man’s preconception stress may program his kids for mood disorders. Researchers found a pathway in the brain that transmits signals about stress hormones, and it may be passed down to the next generation.  If the signal is passed on to you, then your father’s stress levels could affect your predisposition for anxiety and depression.

These studies represent clues to learning how genetic material is transformed as it passes through generations. It’s also a reminder that following a healthy diet, staying active and maintaining mental health is important for everyone at every age.

Happy Father’s Day!

– Erica Roth

A Healthy Diet: A Prescription for a Healthy Life!

food pyramid pie chart

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We have all heard the phrase “You are what you eat.” Not only is there a lot of truth in that little saying, it is also a great reminder for us to be aware of everything we put into our bodies. Everything we eat and drink has an effect on our being and our physical and mental health depends on proper nutrition.

Most people know that nutrition means getting the right amount of nutrients to fuel our bodies and brains. But the difference between the types of nutrients can be less clear.

Nutrients are divided into three categories: micronutrients, macronutrients and water.

Micronutrients are vitamins, minerals and substances such as sodium and potassium called electrolytes. They are essential for growth, development and normal cellular activities. A wide variety of fruits, vegetables and animal products such as meat and dairy are rich in micronutrients.

Macronutrients include carbohydrates (sugar and starches), protein and fats. Macronutrients are extremely important because they give us the calories we need to produce energy. Each person needs a different amount of macronutrients depending on their body size, body composition and level of physical activity. This last point—activity level—is key. We often eat and drink far too many calories for our body’s needs and store the extra calories as fat. The excess fat can become a big problem, causing inflammation, problems with metabolism and cardiovascular issues.

Water is important for maintaining your body’s fluid balance and for functions such as digestion, circulation and body temperature. We also need water to carry nutrients throughout our body and to energize our muscles.

The lack of proper nutrition is still an issue in areas of the U.S. and other Western countries. However, consuming too many calories without enough nutrients is also a critical health problem in the developed world. In fact, the definition of “malnutrition” has been updated to include overnutrition. The expanded definition of malnutrition highlights the serious threat that overnutrition and obesity have on human health.

If you want to learn more about how to fit better nutrition into your life, visit the U.S. Department of Agriculture’s Choose My Plate website. This tool can help jump-start your nutrition knowledge and get you on your way to feeling great.

Audrey Vasauskas

 

When’s the Best Time to Eat? Your Body Clock Knows

 

Two teenager girls, sisters, eats fastfood on the street

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The American Heart Association recently released a statement suggesting that when and how often you eat could affect your risk for developing heart disease and stroke. Until now, the focus on diet has been primarily about how much and what you eat. This news—that the time of day you eat may also be important—could change the way people are able to manage their health.

Our bodies have natural daily patterns called circadian rhythms that occur roughly over a 24-hour cycle. Many biological processes are driven by circadian rhythms, including when you go to sleep and wake up, your body temperature, heart rate, blood pressure and the release of various hormones. A “master clock,” a tiny group of cells called the suprachiasmatic nucleus (SCN), located in the hypothalamus area of the brain manages circadian rhythms. This master clock is mostly controlled by changes in light.

Every cell in the body also has its own internal clock called a “peripheral clock.” Peripheral clocks make sure all of the cells’ functions are coordinated with the master clock. Animal studies show us the importance of keeping peripheral clocks in sync with the brain’s master clock. For example, when the peripheral clock in a mouse’s heart is disrupted, the mouse develops heart failure and dies at a much younger age than normal mice.

Unlike the master clock, peripheral clocks are more responsive to the availability of food than changes in light. As a result, eating at the “wrong” time of day could shift the rhythms of the peripheral clocks so they are out of sync with the master clock. For example, shift workers who work in the middle of the night are active when they would normally be asleep and eat at times when their body doesn’t expect food. They are at much greater risk for being overweight, becoming insulin resistant and developing cardiovascular disease because their master and peripheral clocks are likely to be out of sync.

Research in mice has shown that if they consume a high-fat meal at the end of their active period (the equivalent of a high-fat dinner for humans) they gain more weight, develop insulin resistance and have impaired cardiac function compared to mice that eat the same high-fat meal at the beginning of their active phase (breakfast).

Studies in people suggest that eating meals late in the day is linked to negative health effects, but a direct relationship has not been shown. Nevertheless, if when you eat is just as important as what you eat, it might not hurt to eat your larger meals earlier in the day if you can.

 

John Chatham

John Chatham, DPhil, is a professor of pathology and director of the Division of Molecular and Cellular Pathology at the University of Alabama at Birmingham.

How Your Brain Decides to Keep Your New Year’s Resolutions (or Not)

 

New Year goals or resolutions

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ispy-physiology-100th-post-imageThe start of a new year can feel like a fresh slate or an unwritten book. It’s a chance for many of us to resolve to do things better (eating, exercising) or to stop doing certain things altogether (smoking). But most people don’t succeed in sticking to their resolutions in the long term, and the reason might surprise you. It’s not always a question of lacking willpower or being lazy. Keeping resolutions makes your brain work hard, and that mental effort takes time and practice.

Researchers from the University of Minnesota found that your brain uses more than one decision-making system to build and regulate habit-forming and goal-directed behaviors. One system looks at the steps you take to make a decision. Another evaluates your actions and decides when you need to change a new behavior in order to receive a reward.

Here’s where the hard work comes in: The researchers explain that goal-directed behavior requires mental energy and planning. You have to plan ahead before making decisions to know how to reach your goal. Let’s say, for example, you’re trying to cut back on sweets and are invited to a party. If you want to enjoy a dessert at the party but don’t want to completely ignore your resolution, you’ll need to plan to eat less sugar during the rest of the day. Over time, as you keep making more goal-oriented decisions, the choices become more automatic.

Another study suggests that nerve cells stick together when you form a habit that you’ve enjoyed (such as eating dessert after dinner). The strong bond they create can be tough to break, and—like getting up early to go running or sticking to that diet—it isn’t always easy. This is especially the case when your emotions take over and you feel resentful or angry at the challenging changes you’re trying to make. Being mindful and keeping your emotions out of the decision-making process can help. Your brain, like your body, just needs time to adjust to your new routines.

Good luck and happy new year.

Erica Roth

Can Alcohol Cause Irregular Heartbeat?

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Alcohol and heart health have a complicated relationship. Recent research suggests that moderate drinking may reduce your risk of stroke. But for some people, even one or two drinks a day may increase the risk of a form of heart disease called atrial fibrillation (AFib).

AFib is an irregular heartbeat of the two upper chambers of the heart (atria). During an episode of AFib, the atria beat quickly and out of synch with the lower chambers of the heart (ventricles). This irregular pattern can cause blood to clot in the heart, which also increases the risk of stroke.

A recent study published in the Journal of the American Heart Association suggests that over time, moderate alcohol consumption may cause the left atrium to become larger. The enlargement of the heart chamber can lead to AFib in some cases. This is one of the first studies to show in a large population of humans that structural changes in the heart can cause AFib. Previously, AFib had been thought to arise as a result of problems with the electrical impulses in the heart.

For most people who follow a heart-healthy diet, exercise and don’t have high cholesterol or high blood pressure, the occasional drink probably won’t hurt or lead to AFib. However, it’s a good idea to be aware of the alcohol-related heart disease risk as office parties and family gatherings get into full swing this holiday season.

Learn more about atrial fibrillation from the Mayo Clinic.

Erica Roth

Handling the Pain of Acid Reflux at Holiday Time

Acid reflux

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With Thanksgiving coming up, eating—of all things rich, indulgent and delicious—is top of mind for many Americans. But for people with gastroesophageal reflux disease (GERD), eating this type of food often and in large quantities can be a challenge. This week is GERD Awareness Week, a good time to learn how to prevent GERD symptoms and still enjoy your holiday season.

GERD is the return of stomach contents, including acid, into the esophagus, sometimes known as acid reflux. More than 60 million people in the U.S. experience GERD symptoms, such as frequent heartburn, at least once a month.

You may have a higher risk of having GERD if you:

  • produce a lot of gastric acid
  • have a hiatal hernia
  • have a weak lower esophageal sphincter (the ring of muscle between the esophagus and stomach)
  • are obese
  • smoke
  • drink alcohol or a lot of caffeine

Women have additional risk factors, including being a young adult and adopting a stooping or slouching posture. Certain foods, including peppermint, chocolate, fatty or fried foods, and acidic fruits, also raise the risk of developing heartburn and acid reflux.

Simple dietary and lifestyle changes can be effective for many people to reduce the frequency and intensity of GERD symptoms, including:

  • losing weight if needed
  • quitting smoking
  • eating small meals throughout the day
  • avoiding foods that cause symptoms
  • waiting at least two hours before lying down after a meal

Another first line of treatment is medication, such as antacids or proton pump inhibitors. These drugs are available over the counter and by prescription from your doctor and reduce or stop the production of stomach acid to prevent symptoms.

If occasional heartburn bothers you after a big meal, try making lifestyle changes to help you feel better. If your symptoms persist, your doctor may look deeper into the possible causes for your discomfort. Knowing the risk factors for GERD can help you avoid complications and stay healthy throughout the holidays and all year long.

To learn more about GERD, visit the National Institute of Diabetes and Digestive and Kidney Diseases website

 

layla-al-nakkashLayla Al-Nakkash, PhD, is a professor in the Department of Physiology, at Midwestern University, Glendale, Ariz. She is the course director for medical physiology for medical and podiatry students. Her area of research relates to understanding how intestinal dysfunction (in diseases such as cystic fibrosis and diabetes) can be ameliorated by changes in diet.

The Antioxidant-Activity Connection

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Antioxidants: It’s one of the biggest health buzzwords today. The fabled powers of these mysterious compounds have been featured on daytime TV, plastered on age-defying beauty products and foods in the grocery store, and sold to us as a major reason to frequent juice bars and smoothie shops. Antioxidants are not just an overblown fad, though. They play an important role in keeping our bodies healthy, and they are critical for some people, such as patients with chronic obstructive pulmonary disease (COPD), who can’t get enough oxygen and are inactive as a result.

Antioxidants neutralize molecules called reactive oxygen species (ROS). ROS compounds are byproducts of our body’s metabolism, and too much of them can damage DNA, change cell structure and even kill cells. We can acquire antioxidants to combat ROS by eating foods such as berries, nuts and sweet potatoes. In addition, the body has its own array of natural antioxidants to destroy ROS. Inactivity and low oxygen in the blood (hypoxia) that occur in COPD alter the body’s levels of ROS and antioxidants and can worsen the disease. Maintaining healthy levels of ROS and antioxidants in patients with COPD is a concern for health care providers.

A new study published in the Journal of Applied Physiology found that a low level of activity may be enough to raise antioxidant levels. In a 10-day study, healthy women were confined to strict bed rest, confined to bed rest while breathing air with 32 percent less oxygen, or breathed the low-oxygen air but could stand, walk and conduct normal daily activity. Blood samples were taken before, during and after the experiment to compare the balance between ROS and antioxidant levels. ROS levels increased in all three groups, but the most noticeable difference was in the active group, which had higher antioxidant levels than those on bed rest. Although low oxygen in the blood increased the ROS levels of the participants in the active group, maintaining a somewhat active lifestyle allowed their bodies to produce more antioxidants to buffer the damaging ROS compounds.

There’s a growing population of patients with lung disease who experience both inactivity and hypoxia, so research that helps identify additional consequences of hypoxia and inactivity is paramount for improving care. This study suggests that if these patients can maintain some degree of their physical routine, they may be protected from some of the damaging effects of ROS. This research also provides evidence health care workers can use to educate and encourage healthy behaviors in their patients to reduce complications caused by too much ROS.

Thomas J. Otskey, Hannah Grace Deery, Sandra Bigirwa, Sarah Small and Erin Feldott are students in the Department of Health and Human Physiology at the University of Iowa studying respiratory physiology with Melissa Bates, PhD.

Capsaicin Causes Pain, No Gain

Emily Johnson Capsaicin

William Yang presents “Capsaicin suppresses body weight gain and pain reaction in mice” at the Experimental Biology 2016 meeting in San Diego. Credit: Emily Johnson

Capsaicin is a chemical people love or hate. It’s the chemical in hot peppers and spicy foods responsible for their spicy (and sometimes painful) taste, but researchers in Maryland and Pennsylvania think it may have some health benefits. William Yang, a high school student who worked on the project at the Temple University Lewis Katz School of Medicine in Philadelphia, shared their findings at the Experimental Biology meeting in San Diego.

The research team gave mice capsaicin for a total of 90 days. Mice fed capsaicin gained 16.5 percent less weight than mice in the control group, suggesting that capsaicin either changed their appetite or their body’s metabolism. The mice also showed changes in their ability to handle high blood sugar and high insulin levels, indicating that capsaicin has effects on metabolism.

Yang says future studies are underway in the group’s laboratory to discover how and why these changes happened. In the meantime, the findings tell us that the beneficial effects of eating spicy foods might be worth a little bit of pain.

 

Emily JohnsonEmily Johnson, PhD, is an APS member and a former volunteer editor for the I Spy Physiology blog.