The Fat-blocking Powers of Fiber

Leafy green vegetables

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An estimated 610,000 people in the U.S. die from heart disease each year. One common cause of heart disease is the narrowing of blood vessels due to the buildup of fatty deposits (plaque). Many factors—including eating a lot of fatty foods—can lead to plaque buildup in blood vessels.

Your liver processes excess fat by packaging it into cholesterol droplets known as low-density lipoproteins (LDLs). LDLs travel throughout the body in the blood. Often, the droplets get stuck to the blood vessel walls, where they accumulate. The buildup of plaque eventually blocks blood flow, most often in the blood vessels that supply blood to your heart. However, eating fiber can help prevent the early stages of heart disease and plaque buildup.

Fiber is a plant’s supply of stored energy, but your gut can’t digest it. During a meal, your small intestine breaks down the food you eat and absorbs nutrients. Fiber resembles a mesh-like structure. Indigestible fiber acts like a large net—think of a butterfly net—to block places where fat can be absorbed. A meal high in dietary fiber blocks some of the absorption of fats, stopping fats from moving outside the gut into the bloodstream.

When there is less fat absorbed from your gut, your liver does not have to package it into LDL droplets, which lowers LDL levels in the blood. In addition, when your liver needs fat to make hormones and bile, it can produce another kind of cholesterol called high-density lipoproteins (HDL). HDL can remove some of the plaque in blood vessels and send it back to the liver. HDL is known as “good cholesterol” for this reason. Consuming meals high in fiber can help HDL with this process.

Recent studies have shown that eating fiber-rich brown rice or taking more than 5 grams of fiber supplements daily can improve some measures of cardiovascular function in adults. Leafy or green vegetables such as spinach, lettuce and broccoli are also good sources of fiber. So make a salad or try adding greens to an entree or a smoothie—I promise you can’t even taste blended spinach in a fiber-packed smoothie. There are plenty of options to fiber up your diet and keep your heart healthy.

Gabrielle RoweGabrielle Rowe is a PhD candidate in the physiology program at the University of Louisville. She is interested in studying small heart vessel function, stem cells and aging.

How, What and When to Eat: Scientists Weigh In at Experimental Biology 2018

Each year, scientists who study physiology and other biomedical research fields—including anatomy, biochemistry, pathology and pharmacology—gather at the Experimental Biology (EB) meeting. Scientific meetings such as EB provide a platform to present and learn about new and cutting-edge research and form collaborations with colleagues that can lead to advances in science and medicine. This year’s EB meeting in San Diego featured studies ranging in topics from nutrition and exercise to mental well-being and women’s health. Read on for more about how the food we eat—and when we eat it—affects the body.

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You may already know that probiotics—live bacteria found in yogurt and nutritional supplements—are good for digestive health. Now researchers from Auburn University in Alabama have found that drinking kefir, a fermented milk-based beverage, may help lower blood pressure. Their study suggests that probiotic-rich kefir restores balance to bacteria in the intestines and an enzyme in the brain that controls nervous system function. It seems the gut and brain are working together to regulate blood pressure.

Diner: Artificial Sweetener Caddy

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Have you replaced the sugar in your morning coffee with a no-calorie artificial sweetener? This approach may help you cut calories, but according to researchers from the Medical College of Wisconsin, it may not reduce your risk of obesity or diabetes. Their data suggest that zero-calorie sweeteners change how the body processes fat and gets energy. Moderation with any type of sweetener, artificial or natural, seems to be the key.

eating breakfast

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Breakfast skippers: New research from the Mayo Clinic suggests that passing on breakfast may be a cause of weight gain. Adult volunteers were found to gain less weight when they ate breakfast at least five days a week when compared to those who broke their fast later in the day. The results appear to confirm what your mother always told you: “Breakfast is the most important meal of the day.”

If you’re considering becoming pregnant, make sure your prenatal multivitamin includes zinc. Researchers at Pennsylvania State University found zinc is crucial for the health of a woman’s eggs. Zinc deficiency seemed to impair the development of eggs very early on, months before they are ready for release (ovulation) and fertilization. Zinc-deficient eggs were smaller and had problems with cell division, which can prevent fertilization from occurring.

Alternate-day fasting is a weight loss method that’s recently become more popular—but does it work? A research team from Kent State University in Ohio found that obesity-prone mice lost more weight when their calories were restricted every other day than lean mice did. This was the case even though the mice burned the same amount of calories on fasting and non-fasting days. The results suggest that alternate-day fasting may be effective in some people, but not as much in others.

Interested in learning about more research presented at the meeting? Read Meditation, Stress and Mental Fatigue: Research from Experimental Biology 2018.

Erica Roth 

Hypertension: Silent and Unequal

Nurse checking blood pressure for mature African American man

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High blood pressure has been coined the “silent killer” because it has no symptoms, which causes many people to go undiagnosed. A blood pressure reading that stays high for long periods of time is called hypertension. It’s one of the leading risk factors for heart disease.

In addition to being silent, hypertension is also unequal—rates in black people are much higher than in any other racial group in the U.S. An estimated 46 percent of black adults in the U.S. have hypertension. But because guidelines for diagnosis changed recently, this number is likely to be underestimated.

The physiological reasons behind this racial discrepancy are unclear. Some studies suggest differences in the response to stress. One study showed that young black men had greater nervous system responses than white men when faced with a physically stressful situation—in this case, plunging their hand into an ice water bath.

The researchers looked at activity (called sympathetic activity) in a part of the nervous system that regulates heart rate, force of heart contractions and can decrease the size (constriction) of the blood vessels. Constriction of blood vessels during exercise is good, as it redirects blood and oxygen to the muscles. However, too much sympathetic activity can result in unneeded blood vessel constriction and an increase in heart rate that significantly raises blood pressure. The black participants’ surge in sympathetic activity in the ice water test was accompanied by large spikes in blood pressure, which has been linked to future development of hypertension.

A more recent study suggests that the racial disparity may also lie in the blood vessels’ response to nervous system activity during periods of rest. The researchers inserted a tiny probe into a nerve of the leg to measure sympathetic activity in the muscles. They also looked at blood flow in the artery of the leg and blood pressure throughout the resting period. They found that black men had greater vessel constriction and higher blood pressure than white men, even when accounting for other variables that may affect blood pressure such as weight.

Seeing how blood vessels react—or overreact— to nervous system activity helps scientists understand more about the factors that potentially increase the risk of hypertension in black adults. The next step is to find ways to reduce these responses and lower the risks of hypertension and heart disease in this population.

April is National Minority Health Month. Visit the U.S. Department of Health and Human Services’ Office of Minority Health to learn how people from diverse cultures can stay healthy.

Yasina Somani cropYasina Somani, MS, is a PhD student in the Cardiovascular Aging and Exercise Lab at Penn State. She is interested in studying the effects of novel exercise and nutritional therapies on cardiovascular outcomes in both healthy and clinical populations.

Spotlight On: Tuberculosis

Pulmonary Tuberculosis

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If you’ve ever volunteered or worked in a hospital, nursing home or laboratory, you may remember having a tuberculosis (TB) skin test. But did you fully understand what TB is and why the tests are necessary? Though TB may not seem to be a major health concern in the U.S., this cunning disease remains a leading cause of death worldwide and a major risk to people with weak immune systems.

A strain of bacteria called Mycobacterium tuberculosis causes TB. People who are exposed to the bacteria may develop a form of the disease without actually being sick. This is called latent TB infection and means the body is able to fight the bacteria without spreading it to others. However, if the immune system is not in top-notch shape, the bacteria can multiply and develop into a dangerous active infection. Active TB infection is very serious and can be deadly if not treated.

An active TB infection can be spread easily, especially when the disease attacks the lungs (pulmonary TB). The bacteria spreads from one person to another through the air. When someone with active pulmonary TB coughs or even speaks, tiny droplets sent out from the lungs carry bacteria through the air. The droplets can easily be inhaled by others, especially in close contact. Common symptoms of pulmonary TB include chest pain, coughing—sometimes coughing up blood and mucus—and wheezing. People with active TB infection may also feel weak and have fever, chills or no appetite.

You might wonder what all this has to do with skin tests. Because active TB is so dangerous and because latent TB can develop into active disease, people who have a high risk of developing TB and their caregivers need to be tested for the disease. A small amount of solution containing an inactive part of the bacteria is injected under the skin. If the skin at the injection site doesn’t change, everything is fine. But if the skin becomes red or swollen, this indicates there are TB bacteria in the body and treatment is necessary.

Although the number of people infected in the U.S. has been steadily declining, more than 10 million people worldwide were sickened by TB in 2016. March 24 is World Tuberculosis Day. Learn more about how to stop the spread of TB.

Audrey Vasauskas

Curcumin, the Golden Spice

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Growing up, I enjoyed spending time in my grandmother’s kitchen. Her cooking usually involved an array of colorful spices, including a generous mix of curry powder in nearly every Indian recipe. You can’t mistake the tantalizing smell—cooking with this yellow-tinted powder can fill a room quite quickly. But it appears that there is much more to the aromatic spice than first meets the nose. It may help maintain heart health, too.

Turmeric, one of the spices that make up curry powder, contains curcumin. Evidence suggests that consuming curcumin has a wide range of physiological effects that may be beneficial to health. Curcumin is rich in antioxidants and acts as an anti-inflammatory, which may help explain its ability to promote nitric oxide (NO) availability. NO is a key compound in maintaining the health of our blood vessels. Scientists think that the body makes less NO and more becomes inactive as we age. Consequently, there is less available as we get older.

Also as we age, our blood vessels aren’t able to expand (dilate) as well. They become stiffer and less flexible and more likely to become clogged. Older people have a greater risk for developing high blood pressure due to the increased stiffness and reduced flexibility of the blood vessels. This process is called vascular aging. Women appear to experience vascular aging more quickly after menopause when the hormone estrogen is no longer produced.

A study of healthy middle-aged and older women in Japan found that taking curcumin supplements for eight weeks improved the blood vessels’ ability to dilate and reduced stiffening of the carotid artery in the neck. A recent study in the Journal of Applied Physiology found that exercise training alone does not protect against blood vessel stiffening in postmenopausal women. Therefore, combining exercise training with curcumin may be a promising way for women to slow down the steep decline in vascular health after menopause.

Another study of healthy middle-aged and older adults found that 12 weeks of curcumin supplementation improved NO availability and reduced oxidative stress (a type of cell damage) to improve blood vessel function.

These studies show promise for curcumin as a preventive therapy to lower heart disease risk in both men and women.

It seems that this golden spice really is a spice for life and may help prevent cardiovascular disease—the leading cause of death in the United States and worldwide—in older people.

March is National Nutrition Month. Learn more about how eating a balanced diet can improve your health at the Academy of Nutrition and Dietetics website.

Yasina Somani cropYasina Somani, MS, is a PhD student in the Cardiovascular Aging and Exercise Lab at Penn State. She is interested in studying the effects of novel exercise and nutritional therapies on cardiovascular outcomes in both healthy and clinical populations.

Can Eating Fruit Be Hazardous to Your Health?

Assortment of fruits

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The U.S. Department of Agriculture recommends two cups of fresh, frozen, canned or dried whole fruits each day for most people following a 2,000-calorie diet. However, some people have difficulty breaking down fruit in their digestive tract or absorbing fructose into their bloodstream. Fructose is a type of sugar that is naturally found in fruit. Humans have a limited ability for absorbing fructose. A special protein called GLUT5 carries fructose into the small cells of the intestines, and another protein called GLUT2 takes fructose from the cells and into the bloodstream.

People with fructose malabsorption (formerly called dietary fructose intolerance) have a deficiency of GLUT5 in their intestinal cells. Bacteria in the intestinal tract break down the fructose that the body can’t absorb. The undigested fructose forms gas and often causes gastrointestinal discomfort. Symptoms may include bloating, gassy pain and diarrhea. Up to 50 percent of adults can’t absorb large amounts of fructose, and about 10 percent can’t absorb even moderate amounts of fructose.

In addition to fruit, a number of sweeteners are high in fructose. High-fructose corn syrup, honey, maple-flavored syrup, molasses, sorghum and invert sugar may also cause uncomfortable symptoms. One possible reason why fructose malabsorption rates in the U.S. are high is from the widespread consumption of beverages—such as soft drinks—sweetened by high-fructose corn syrup.

People who have fructose intolerance should limit their consumption of high-fructose foods, such as:

  • fruit juices,
  • apples,
  • grapes,
  • watermelon,
  • asparagus,
  • peas, and
  • zucchini.

Fruits and vegetables that are lower in fructose may be easier to digest, especially when they are part of a full meal. Lower-fructose foods include:

  • bananas,
  • blueberries,
  • strawberries,
  • carrots,
  • avocados,
  • green beans, and
  • lettuce.

So, if you are trying to eat the recommended servings of fruit every day but have digestion issues, ask your doctor if you may have fructose malabsorption and try lower-fructose foods as an alternative.

barb-goodmanBarb Goodman, PhD, is a professor of physiology at the University of South Dakota.

2017’s 10 Most-read Posts

Using technology to take brainstorming to the next level

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Another physiology-filled year on the I Spy Physiology blog is almost over. This year, we’ve explored dozens of topics, ranging from skin cancer, gut health and spinal cord injury to the mystery of how hibernating animals’ muscles remain strong. We’ve celebrated women in science and smiled at the thought of turkeys running on treadmills. Today, we’re highlighting the 10 most-read posts of 2017.

Scholarly articles highlight the need for more research about women’s responses to illness and disease risk. In that vein, our most popular post this year looked at the relationship between sex-specific hormones and asthma. Posts about the danger of e-cigs—especially in the under-21 set—and how muscle rebuilds during the daunting feat of cycling the 500-mile Colorado Trail rounded out the top three. Take a look at this year’s top 10:

  1. When Hormones Take Your Breath Away
  2. The Trouble with E-Cigs: Why They May Pose More Harm than Good
  3. Muscle Rebuilding on the Colorado Trail
  4. Beer Does a Body Good?
  5. Meet Karyn Hamilton, Health and Exercise Science Professor
  6. Dog Gazing: Bond between Hound and Human
  7. Why Does Air Pollution Affect More Women than Men?
  8. When Vampires Attack: How Your Body Reacts to Extreme Blood Loss
  9. Microvesicles and Blood Vessels and Exercise, Oh My!
  10. The Hispanic Paradox: Why Are Some Ethnic Groups Living Longer than Others?

We’d love to hear what you’d like us to feature next year. Share your thoughts in the comments or send us an email. And don’t forget to follow our blog in 2018.

Erica Roth 

Exploring Causes and New Treatments for Sickle Cell Disease


Shaina Willen, MD, of Vanderbilt University Medical Center, presents her poster at the Physiological and Pathophysiological Consequences of Sickle Cell Disease conference.

Sickle cell disease (SCD) is a lifelong disorder of the red blood cells. It’s caused by a mutation in a single gene and affects about 100,000 people in the U.S. Normal red blood cells are round, a shape that helps the cells carry oxygen around the body. But red blood cells in people with SCD can become abnormally shaped like a crescent (sickle), which can cause blood cells to get stuck in blood vessels and interfere with blood flow, leading to severe pain.

Scientists and medical doctors who specialize in SCD gathered last month in Washington, D.C., for the American Physiological Society conference “Physiological and Pathophysiological Consequences of Sickle Cell Disease.” They discussed new research into the causes of the disease and new therapies that can treat and even prevent SCD-related pain episodes. Read on to learn more about their findings.

Certain patients with SCD may have a higher risk than others of developing complications—such as increased pain, stroke, eye problems and kidney disease—but finding out which patients have a higher risk is challenging. New research from Vanderbilt University Medical Center has uncovered a genetic marker that may be able to identify which patients are more likely to have these complications.

Emotional stress is known to trigger or worsen physical symptoms of disease, including some types of pain. A group of researchers from California found that stress and the anticipation of pain causes blood vessels to become narrower (vasoconstriction). In people with SCD, vasoconstriction can be dangerous because abnormally shaped (sickled) cells may be more likely to get stuck in the blood vessels and block blood flow.

A healthy digestive system is typically filled with various types of bacteria that aid in digestion. However, researchers from Howard University found that people with SCD are more likely to have higher levels of one specific bacterium, Veillonella. Veillonella link together to form a film in the digestive tract, which can attract red blood cells. When red blood cells stick to the film, it can block blood flow to the rest of the body, which causes increased pain. This discovery may help scientists find a way to rebalance gut bacteria levels and reduce symptoms.

These studies are just a few examples of the high-caliber SCD research being done. Read more highlights from this year’s conference:

Alzheimer’s drugs may improve red blood cell function and quality of life

Scientists explore ways to create red blood cells outside the body and prevent sickling

Erica Roth 

The Trouble with E-Cigs: Why They May Pose More Harm than Good


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The market for electronic cigarettes (e-cigs) and vaping has surged in popularity within the past five years, while traditional cigarette sales have declined. From 2012 to 2013, e-cig sales more than doubled to $1.7 billion. By 2015, sales were estimated at $3.7 billion.

Although manufacturers claim that e-cigs are safer than traditional cigarettes, their use has been associated with clear health risks. E-cigs may seem like they are producing harmless water vapor, but that vapor has been shown to contain a mix of cancer-causing chemicals. Some of the toxin levels are comparable to those in cigarettes.

E-cigs are associated with cellular damage and decreased cough reflex sensitivity after just one use. Cough reflex—triggered by chemical or mechanical irritants—protects the upper respiratory system from infection by getting rid of respiratory secretions (mucus) and foreign material from the lungs. Decreased cough reflex sensitivity may increase the risk of infection because mucus and foreign material aren’t always cleared immediately from the airways. Studies on animals have found that nicotine-containing e-cig fluid may cause changes in the lungs similar to what humans experience with chronic obstructive pulmonary disease (COPD). COPD is a condition often seen in long-term smokers. These changes include narrowing of the airways, more mucus production and increased inflammation. E-cig vapor has also been linked to substantial DNA damage and increased cancer risk and decreased lung function.

no smoking no vaping sign ban cigarette and electronic cigarette not allowed blue e-cigarette and cigarette in red circle realistic vector illustration

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More and more research is providing evidence that e-cigs pose serious health risks. One of the greatest concerns is the potential serious long-term consequences in teenagers. Teens are easy targets for tobacco and e-cig advertisers and may also be easily swayed into becoming lifelong tobacco users. Because of the potential health risks of e-cigs, the American Academy of Pediatrics recommends raising the legal purchasing age for both traditional cigarettes and e-cigs from 18 to 21. Marketing strategies of e-cigs try to make e-cigs look socially acceptable to young adults and teens by promoting candy-inspired flavors and vapor tricks on social media. The tendency for the e-cig market to prey on young adult consumers is particularly troubling because the brain is developing critical circuitry that relates to lifelong habits during this time. Users younger than 21 tend to remain nicotine users for life.

The Great American Smokeout sponsored by the American Cancer Society, is November 16. This event is designed to help smokers make a plan to quit, whether it’s traditional tobacco products or e-cigs. Their health depends on it.


Leigh Graziano croppedLeigh Graziano, MS, is a second-year medical student at the Alabama College of Osteopathic Medicine. She works with Audrey Vasauskas, PhD, on research on pulmonary arterial hypertension, which is high blood pressure in your lungs. In her free time, Leigh enjoys yoga, mountain biking and fishing.

Why Does Air Pollution Affect More Women than Men?

Los Angeles Smog

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A year ago, I went to California to participate in a scientific conference. After a couple of days, my mentor and I started to have trouble breathing. As two healthy adults, we wondered why this was happening. I did not know the answer at that time, but I did notice a pattern: Other female colleagues, especially those with asthma, were also struggling to breathe, but not many men were. Our symptoms got better once we left the conference. A research study we later performed in our lab helped us understand what had happened. We discovered some differences in lung function among male and female mice exposed to ozone and other air pollutants, and we learned that females had worse symptoms than males. So something in the air caused our breathing problems.

In the past decade, air pollution has become the world’s single biggest environmental health risk, causing about 7 million deaths—nearly one of every eight—worldwide each year. According to the Air Quality-Life Index, increased air pollution concentration levels may shorten your lifespan by one month if you live in New York and by up to eight months if you live in California. Exposure to pollutants such as ozone, biomass fuels, and fine particles like soot and smoke has been strongly associated with increased mortality from lung disease. As the evidence piles up, we are starting to realize what a big problem these little molecules create—and that what you can’t see can kill you.

Researchers have shown that women are more susceptible to the negative effects of air pollution than men are. The exact reason remains unclear, but we know that men have more relative fat mass, which gives them a larger distribution volume for chemical particles in the environment. Women’s bodies also metabolize pollutants more quickly than men’s, resulting in higher toxicity. A recent study in the American Journal of Physiology—Lung Cellular and Molecular Physiology has shown that sex steroid hormones are somewhat responsible for the male and female differences, indicating that both sex and air pollution may alter the effectiveness of lung immunity.

The American Lung Association offers these and other tips to help protect you from unhealthy air:

  • Check daily air pollution forecasts.
  • Avoid exercising outdoors when pollution levels are high.
  • Avoid exercising near high-traffic areas.
  • Use less energy in your home.
  • Explore other alternatives to driving your car (bike, walk).
  • Don’t burn wood or trash.
  • Don’t allow anyone to smoke indoors.

October 22–28 is Respiratory Care Week. Let’s help the world breathe better. Your life and the lives of your loved ones may depend on it.

Nathalie Fuentes OrtizNathalie Fuentes is a PhD candidate in the biomedical sciences program at Penn State College of Medicine. Her studies in Dr. Patricia Silveyra’s lab include the development of sex-specific therapies to treat lung diseases, sex differences in asthma-related lung inflammation triggered by ground-level ozone and the role of male and female sex hormones in lung disease. Nathalie is originally from Caguas, Puerto Rico.