How Digestion Works

The Digestive Process: What Is the Role of Your Pancreas in Digestion?

How Digestion Works | Johns Hopkins Medicine

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Your pancreas plays a big role in digestion. It is located inside your abdomen, just behind your stomach. It's about the size of your hand. During digestion, your pancreas makes pancreatic juices called enzymes.

These enzymes break down sugars, fats, and starches. Your pancreas also helps your digestive system by making hormones. These are chemical messengers that travel through your blood.

Pancreatic hormones help regulate your blood sugar levels and appetite, stimulate stomach acids, and tell your stomach when to empty.

Pancreatic enzymes

Your pancreas creates natural juices called pancreatic enzymes to break down foods. These juices travel through your pancreas via ducts. They empty into the upper part of your small intestine called the duodenum. Each day, your pancreas makes about 8 ounces of digestive juice filled with enzymes. These are the different enzymes:

  • Lipase. This enzyme works together with bile, which your liver produces, to break down fat in your diet. If you don't have enough lipase, your body will have trouble absorbing fat and the important fat-soluble vitamins (A, D, E, K). Symptoms of poor fat absorption include diarrhea and fatty bowel movements.
  • Protease. This enzyme breaks down proteins in your diet. It also helps protect you from germs that may live in your intestines, certain bacteria and yeast. Undigested proteins can cause allergic reactions in some people.
  • Amylase. This enzyme helps break down starches into sugar, which your body can use for energy. If you don’t have enough amylase, you may get diarrhea from undigested carbohydrates.

Pancreatic hormones

Many groups of cells produce hormones inside your pancreas. Un enzymes that are released into your digestive system, hormones are released into your blood and carry messages to other parts of your digestive system. Pancreatic hormones include:

  • Insulin. This hormone is made in cells of the pancreas known as beta cells. Beta cells make up about 75% of pancreatic hormone cells. Insulin is the hormone that helps your body use sugar for energy. Without enough insulin, your sugar levels rise in your blood and you develop diabetes.
  • Glucagon. Alpha cells make up about 20% of the cells in your pancreas that produce hormones. They produce glucagon. If your blood sugar gets too low, glucagon helps raise it by sending a message to your liver to release stored sugar.
  • Gastrin and amylin. Gastrin is primarily made in the G cells in your stomach, but some is made in the pancrease, too. It stimulates your stomach to make gastric acid. Amylin is made in beta cells and helps control appetite and stomach emptying.

Common pancreatic problems and digestion

Diabetes, pancreatitis, and pancreatic cancer are three common problems that affect the pancreas. Here is how they can affect digestion:

  • Diabetes. If your pancreatic beta cells do not produce enough insulin or your body can’t use the insulin your pancreas produces, you can develop diabetes. Diabetes can cause gastroparesis, a reduction in the motor function of the digestive system. Diabetes also affects what happens after digestion. If you don't have enough insulin and you eat a meal high in carbohydrates, your sugar can go up and cause symptoms hunger and weight loss. Over the long term, it can lead to heart and kidney disease among other problems.
  • Pancreatitis. Pancreatitis happens when the pancreas becomes inflamed. It is often very painful. In pancreatitis, the digestive enzymes your pancreas make attack your pancreas and cause severe abdominal pain. The main cause of acute pancreatitis is gall stones blocking the common bile duct. Too much alcohol can cause pancreatitis that does not clear up. This is known as chronic pancreatitis. Pancreatitis affects digestion because enzymes are not available. This leads to diarrhea, weight loss, and malnutrition. About 90% of the pancreas must stop working to cause these symptoms.
  • Pancreatic cancer. About 95% of pancreatic cancers begin in the cells that make enzymes for digestion. Not having enough pancreatic enzymes for normal digestion is very common in pancreatic cancer. Symptoms can include weight loss, loss of appetite, indigestion, and fatty stools.

Your pancreas is important for digesting food and managing your use of sugar for energy after digestion. If you have any symptoms of pancreatic digestion problems, loss of appetite, abdominal pain, fatty stools, or weight loss, call your healthcare provider.


What is Resistant Starch?

How Digestion Works | Johns Hopkins Medicine

You may have already heard something about resistant starch. Maybe that it’s for good for weight loss and controlling glucose? If you haven’t heard about it, now is your time to learn more.

Let’s start with the definition. Resistant starch is a carbohydrate that resist digestion in the small intestine and ferments in the large intestine.

As the fibers ferment they act as a prebiotic and feed the good bacteria in the gut. There are several types of resistant starch. They are classified by their structure or source.

More than one type of resistant starch can be present in a single food.

Benefits of Resistant Starch

When starches are digested they typically break down into glucose. Because resistant starch is not digested in the small intestine, it doesn’t raise glucose. Gut health is improved as fermentation in the large intestine makes more good bacteria and less bad bacteria in the gut.

Healthy gut bacteria can improve glycemic control. Other benefits of resistant starch include increased feeling of fullness, treatment and prevention of constipation, decrease in cholesterol, and lower risk of colon cancer.

Resistant starch is fermented slowly so it causes less gas than other fibers.

Foods Sources

Foods that contain resistant starch include:

  • Plantains and green bananas (as a banana ripens the starch changes to a regular starch)
  • Beans, peas, and lentils (white beans and lentils are the highest in resistant starch)
  • Whole grains including oats and barley
  • Cooked and cooled rice

The amount of resistant starch changes with heat. Oats, green bananas, and plantains lose some of their resistant starch when cooked. Another type of resistant starch is made in the cooking and cooling process. Cooked rice that has been cooled is higher in resistant starch than rice that was cooked and not cooled.

How to Add Resistant Starch to Your Diet

  • Try cooking rice, potatoes, beans, and pasta a day in advance and cool in the refrigerator overnight. It’s ok to reheat the starch before eating. Reheating doesn’t decrease the amount of resistant starch.
  • In place of cooked oatmeal, try uncooked oats soaked in yogurt, milk, or a non-dairy milk and refrigerate overnight (often called overnight oats).
  • Add lentils to a salad or soup.
  • As a partial flour replacement try green banana flour, plantain flour, cassava flour, or potato starch. Resistant starch will be lost when baking or cooking with these flours. You can also supplement with a small of amount (1-2 teaspoons) sprinkled on your food.

When increasing fiber intake, go slowly and drink plenty of water to reduce GI side effects. Remember all types of fiber have health benefits so eat a variety of fiber-containing foods.

by Christine McKinney, RD LDN CDE



Multiple New Research Focused on Microbiome as Scientists Look to the Gut for Answers

How Digestion Works | Johns Hopkins Medicine

Posted on 7/26/2019

Researchers working with animal models traditionally look at the brain, but recent studies are increasingly focused on a different area—the gut, or microbiome, which is emerging as an important factor in human health.

It’s a fertile area of study: The human gut is home to more than 500 different types of bacteria, which line the entire digestive system and play an important role in digestion, metabolism, disease, immunity, mood, and the workings of the nervous system and brain.

Recently, several scientific studies have looked at the microbiome—the mix of bacteria and other microorganisms in the gut—to find clues to other biological manifestations in the body, including diseases, disorders, allergies, and even endurance.

Disrupted Gut Microbiome Linked to Breast Cancer Metastization

The gut microbiome has already been linked to colon cancer, but new research from the University of Virginia has also found a connection between the microbiome and the spread of breast cancer.

Mouse models of the most common type of breast cancer, hormone receptor positive (HR+), were treated with antibiotics to disrupt the microbiome, then were tested for both inflammation and the spread of breast cancer cells.

The disruption in the microbiome caused inflammation in the mice, which enabled tumor cells to more easily metastasize to the blood and lungs.

New Evidence That Parkinson’s Disease Starts in the Gut

A study at Johns Hopkins University School of Medicine using a new mouse model of Parkinson’s disease has found that Parkinson’s can begin in the gut and spread to the brain via the vagus nerve.

The research team injected pathologic α-synuclein, one of the hallmarks of Parkinson’s, into the gut of mouse models. Within a month the pathologic α-synuclein had spread to the lowest part of the brainstem, and within three months it had reached beyond the brainstem to the amygdala, hypothalamus, and prefrontal cortex.

By seven months it had appeared in the hippocampus, striatum, and olfactory bulb, and the mice were showing signs of depression, anxiety, olfactory dysfunction, and cognitive deficits, all of which are common symptoms of Parkinson’s disease.

A Gut Bacteria That Alleviates Food Allergies

Scientists at Boston Children's Hospital and Brigham and Women's Hospital discovered that babies and children with food allergies are missing certain species of gut bacteria. When they gave these missing bacteria to mice, the microbes protected the mice from food allergies.

Scientists were able to isolate two groups of Clostridiales or Bacteroidetes microbes that resulted in food allergy resistance. Some members of the team are now setting up a human trial to test the approach to treat humans with peanut allergies.

Gut Bacteria Can Contribute to Autistic Behavior

Researchers at Caltech transferred gut microorganisms from children with Autism Spectrum Disorder (ASD) into mice, which caused the mice to exhibit behaviors characteristic of ASD, including socializing less with other mice, vocalizing less, and engaging in repetitive actions.

In addition to behavioral changes, the mice colonized with intestinal microbiota from ASD humans also showed a reduction in two metabolites: 5-amniovaleric acid (5AV) and taurine. In further tests, researchers treated a strain of mice, BTBR, that naturally display autistic behaviors, with 5AV and taurine. The BTBR mice showed a decreases in ASD-type behaviors.

The research opens the possibility that ASD may be treated with therapies that target the gut rather than the brain.

Replenishing an Aging Gut Could Revive the Immune System

A study at the Babraham Institute at Cambridge found that transplanting gut bacteria from young mice to old mice resulted in a significant boost in the immune systems of the older mice, partly ameliorating the natural age-related drop in immunity.

A Bacteria That Boosts Endurance

In a study conducted at Harvard Medical School, researchers identified a strain of bacteria commonly found in long-distance runners, especially after running a marathon.

Researchers found that putting this bacteria, called Veillonella, in the colons of mice boosted their performance on a treadmill exertion test by 13%.

Jonathan Scheiman, who led the study, hopes to test Veillonella in humans with the goal of creating a probiotic that improves athletic endurance.

As researchers continue to explore this rich new area of discovery, they’ll no doubt continue to uncover new secrets the microbiome holds.

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Daniel P. Todes, PhD

How Digestion Works | Johns Hopkins Medicine

Phone: 410-955-7079

Research Interests
Social relations of scientific thought; history of biomedical and biological sciences; history of medicine and science in Russia.

My interest in the history of science and medicine originated with my participation in numerous arguments about the Vietnam War in the 1960s and 1970s. I noticed that people rarely changed their minds during these heated debates, regardless of the factual arguments advanced.

So, I became interested in the question “Why do people think what they think?” In college, I looked for an answer in philosophy, psychology, sociology, and, finally, history courses (which I found most satisfying).

From history—particularly, Russian history—I found my way to History and Sociology of Science, which offered interesting approaches to a specific form of my question: “Why do scientists and physicians think what they think?”

I’ve been working on that question for about three decades now, and still find it fascinating.

In my first book, Darwin Without Malthus: The Struggle for Existence in Russian Evolutionary Thought (1989), I explored the ways in which social, cultural, and physico-geographical circumstances shaped the response of Russian naturalists to Darwin’s culturally-laden metaphor “struggle for existence,” and so imparted a characteristic direction to Russian evolutionary thought. Upon completion of this project, I wanted to explore the same general question for experimental science, and settled on a study of Ivan Pavlov. I was fortunate to begin that project in the early 1990s, when Gorbachev’s ‘glasnost’ was making available an avalanche of previously inaccessible archival materials. I embarked on what I conceived as a “scholarly biography accessible to the educated lay person.” By the mid-1990s, I realized that some of the questions that most animated me as a historian of science and medicine could not be addressed in satisfying depth and detail in the biography without losing my lay audience—and so took a “detour” to write a separate monograph on Pavlov’s laboratory and scientific research during the years 1891-1904, which generated the work on digestive physiology for which he won the Nobel Prize. Having completed that book, Pavlov's Physiology Factory: Experiment, Interpretation, Laboratory Enterprise (2002), I returned to the biography.

That biography, Ivan Pavlov: A Russian Life in Science, is now available from Oxford University Press.

I am now collaborating with Eleonora Filippova on a study of Aleksei Ukhtomskii (1875-1942), who, Pavlov, was a member of the Russian Academy of Sciences who studied reflexes and the psyche.

  We are examining Ukhtomskii’s life as a devout Old Believer in late Imperial and Soviet Russia, and the relationship of his scientific work in physiology and psychology to his religious thought and practice.

The frozen Neva River and the Winter Palace, St Petersburg, Dec 2013

Recent Publications

Ivan Pavlov: A Russian Life in Science (Oxford University Press, 2014).

V. O. Kovalevskii: Vozniknovenie, soderzhanie i vospriatie ego rabot po paleontologii (St. Petersburg: Russian Academy of Sciences, 2005).

Pavlov's Physiology Factory: Experiment, Interpretation, Laboratory Enterprise (Johns Hopkins University Press, 2002).

Ivan Pavlov: Exploring the Animal Machine (New York and Oxford: Oxford University Press, 2000). This is a short, unfootnoted biography for middle and high school students.

Darwin Without Malthus: The Struggle for Existence in Russian Evolutionary Thought (Oxford University Press, 1989).

“Global Darwin: Contempt for Competition,” Nature, vol. 462 (November 5 2009), 36-37.

“Stil' myshleniia I. P. Pavlova kak eksperimentatora v rabote po pishchevareniiu” [I. P. Pavlov's style of experimental thinking in his work on digestion], Fiziologicheskii Zhurnal, 99 (85), 9-10 (September 1999), 1290-1302.

“From the Machine to the Ghost Within: Pavlov's Transition from Digestive Physiology to Conditional Reflexes,” American Psychologist, (Fall, 1997), 947-55.

“Pavlov's Physiology Factory, 1891-1904,” Isis, 88 (Summer, 1997), 205-46.

(with Nikolai Krementsov) “Dialectical Materialism and Soviet Science in the 1920s and 1930s,” in William Leatherbarrow and Derek Offord, eds., A History of Russian Thought (Cambridge: Cambridge University Press, 2010).

 “From Lone Investigator to Laboratory Chief: Ivan Pavlov’s Research Notebooks as a Reflection of His Managerial and Interpretive Style,” in Frederic L Holmes, Jürgen Renn, Hans-Jörg Rheinberger, eds. Reworking the Bench. Research Notebooks in the History of Science (Kluwer, 2003), 203-220.

Daniel Todes's teaching relates to his central interest in the relationship of scientific and medical ideas to the context in which they are generated.

Recent courses include “Analogy and Metaphor in Science and Medicine,” “Experiment and the Laboratory in Science and Medicine,” Lives in Science” (a survey of the history of science through contextualized biographies), “Squeezing the Data: Interpretation in Science and Medicine,” “History of Modern Medicine: From Enlightenment to Present,” “The White Plague: History of Tuberculosis,” and “Biography”

Course Syllabi
150.702 Survey of Modern Medicine


Nerve Cells in the GI Tract are Capable of Regeneration | Cell And Molecular Biology

How Digestion Works | Johns Hopkins Medicine

Scientists at Johns Hopkins have reported interesting new evidence that upends common knowledge about gut nerve cells.

Their work suggests that neurons in the mouse digestive tract regenerate, incredibly, about five percent every single day.

This study, published in the Proceedings of the National Academy of Sciences could have major implications for how we treat and understand the digestive system. 

Previous work has posited that healthy adults don’t create new neurons, but Pankaj Jay Pasricha, M.B.B.S., M.D.

, Professor of Medicine and Director of the Johns Hopkins Center for Neurogastroenterology, along with Subhash Kulkarni, M.S., Ph.D.

, Assistant Professor at the Johns Hopkins University School of Medicine, led a team of researchers that revealed a life cycle in the millions of neurons residing in the guts of mice. 

“Scientific dogma believed that gut neurons don’t regenerate and that this ‘brain,’ known as the enteric nervous system, remained relatively static shortly after birth,” Pasricha said. “We now have proof that, not only do they regenerate, but the whole network turns completely over every few weeks in adult animals.”

Proof of nerve cell regeneration, or neurogenesis, has been tough to capture.

For this work, the scientists took samples from mouse intestines the one shown in the video above; in it, the green indicates a network of neural precursor cells, which are constantly making new neurons.

Blood vessels are shown in blue while cell nuclei are grey. The entire enteric nerve system, which controls critical gastrointestinal processes, is recreated in only a few days.

“The yin and the yang of neuronal loss and birth keeps us going,” Kulkarni said.

In their work, the researchers found a high rate of death among the neurons of the small intestines of healthy adult mice. It led them to wonder how the neuronal population stayed constant. “There could be only one answer,” noted Kulkarni. “The high turnover of neurons in the gut could only be reconciled by birth of newborn neurons, or neurogenesis.”

“Although previous studies have shown that regeneration of adult neurons may happen in an injured gut,” Kulkarni says, “by and large, this appeared a relatively isolated and rare phenomenon.

We now provide evidence that this happens continually and robustly in the adult healthy gut.

It helps explain how this nervous system maintains itself, despite constant exposure to dietary factors, toxins, microbes and mechanical forces.”

“We didn’t believe it ourselves, at first,” Pasricha, whose lab has been working on these neural stem cells for many years, says of the findings. “It's an extraordinary result; the mice get an entirely new ‘brain’ in the gut every few weeks.”

He noted that since this work was limited to the mouse small intestine, further research will be necessary in order to find out if other species, including humans, or other parts of the gut undergo the same cellular birth and death processes. The research is ongoing in Pasricha’s Johns Hopkins lab.

The new findings may aid in the identification of new therapies for gastrointestinal motility disorders achalasia, gastroparesis, pseudo-obstruction, colonic inertia and other disorders involving the digestive system.

“And as we dig deeper into this research,” said Kulkarni, “we will gain new insights into a whole host of other diseases that affect not just the gut, but other organ systems with which this nervous system communicates, such as the brain.”

Learn more about the enteric nervous system from the video.

Soures: JHU, PNAS

About the Author

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Aging and Digestive Health

How Digestion Works | Johns Hopkins Medicine

From the WebMD Archives

Getting older has pluses and minuses. On the plus side, you get more time to relax and enjoy life. On the minus side lie many health challenges — including an increase in digestive health disorders. Of course, problems with digestion can occur at any age. Yet nearly 40% of older adults have one or more age-related digestive symptom each year.

Here's an overview of common digestive health problems that may arise with age. Learn why they occur and what you can do to keep your digestive system running smoothly well into your later years.

  • Constipation. One of the most common things we see, certainly as people are getting into their 60s and 70s, may be a change in bowel habits, predominantly more constipation,” says Ira Hanan, MD, associate professor of medicine at the University of Chicago Medical Center. Symptoms include difficult or painful bowel movements, infrequent bowel movements, and hard, dry stool. There are a number of age-related factors that can cause constipation in older adults.
  • Changes in the digestive system. Your digestive system moves food through your body by a series of muscle contractions. Just squeezing a toothpaste tube, these contractions push food along your digestive tract, Hanan says. As we age, this process sometimes slows down, and this can cause food to move more slowly through the colon. When things slow down, more water gets absorbed from food waste, which can cause constipation.
  • Medication use. Older adults take a lot of medications, says Ellen Stein, MD, an assistant professor of medicine at Johns Hopkins Hospital in Baltimore, MD. And as we age, we start to have more health problems that require medications. Several common medications can cause constipation. One example is calcium channel blockers, used for high blood pressure. “Very good for blood pressure, very constipation causing,” says Stein. Narcotic pain relievers are another common culprit. An older adult who has knee or hip replacement surgery will often be given narcotics for pain. “Narcotics have effects directly on the bowel,” Stein tells Web MD. “They actually slow the gut.”
  • Inactivity. People often become less active as they age, says Stein, and being inactive can make you constipated. Bed rest during an illness can cause real problems. If a person has joint-replacement surgery, for example, it takes time to recover and be fully active again. Add narcotic pain relievers to the mix, and “that might change manageable constipation into something that's much more of a problem,” Stein says.
  • Not drinking enough fluids. Staying hydrated helps prevent constipation at any age. It can become more of an issue for older adults who take diuretics for high blood pressure or heart failure. Diuretics lower blood pressure by causing you to lose excess fluid by urinating more often. Some people may avoid drinking too many fluids so they don't have to run to the bathroom all day long. Between urinating more and drinking less, you can become dehydrated.
  • Diverticular Disease. About half of people age 60 and older have diverticulosis. This occurs when small pouches in the lining of the colon bulge out along weak spots in the intestinal wall. While many people don't have any symptoms, gas, bloating, cramps, and constipation may occur. “I tell my patients its part of the aging of the colon,” Hanan tells WebMD. “As we get older, we're more prone to developing these pockets.” Why they occur with age is unclear, he says. While most of the time they don't cause a problem and don't require treatment, they can cause scarring and irregularity. If the pockets become inflamed, it's called diverticulitis, which can cause abdominal pain, cramping, fever, chills, nausea, and vomiting. Antibiotics, pain medications, and a liquid diet treat diverticulitis.
  • Ulcers &NSAIDs. Many older adults use nonsteroidal anti-inflammatory drugs (NSAIDs) to control pain from arthritis and other types of chronic pain. Regular use of NSAIDs increases the risk for stomach bleeding and ulcers. So while aging alone doesn't make your stomach more prone to ulcers, the chronic use of NSAIDs does raise your risk. More often than not older patients don't have pain from ulcers, says Hanan, but they can have painless gastrointestinal (GI) bleeding. If you notice any type of stomach bleeding, such as vomiting blood, passing dark stools, or noticing blood when you wipe, tell your doctor right away.
  • Problems with the mouth and esophagus. The esophagus is the tube that connects our mouth to our stomach. the colon, the esophagus can also slow down with age, moving food through more slowly. This can cause problems swallowing food or fluids. Dementia, stroke, and conditions such as Parkinson's disease can also cause difficulty swallowing.
  • Polyps. After age 50, the risk increases for developing polyps, or small growths, in the colon. Polyps may be noncancerous, they may become cancer, or they may be cancer. “We don't know what causes polyps,” Hanan says. There's been speculation that it's something in the diet or something we don't get enough of, plus genetics. It's probably a cumulative effect over the years, he says. You can have polyps and not know it because they usually don't have any symptoms. “That's why screening colonoscopies are recommended for anyone over the age of 50,” Hanan tells WebMD. During this procedure, polyps can be removed before they become cancer. People with a family history of colon cancer or other risk factors may need to have screenings earlier.
  • GERD. Gastroesophageal reflux disease (GERD) is the most common upper GI disorder in older adults, although people of all ages can get it. GERD occurs when stomach acid backs up into the esophagus, causing heartburn and other symptoms. Heartburn is more common as you get older, says Stein, but it's often caused by factors not related to aging. Eating late at night and eating the wrong types of foods, such as fast food and fried foods, can all cause reflux. Certain medications, including some blood pressure medications, which many older adults take, can cause heartburn. Obesity increases your risk for heartburn and GERD, so if you gain weight as you get older, you could have more reflux.

Just any other health problem, prevention is the best medicine when it comes to keeping your digestion running smoothly. “The things that are good for all older Americans are really good for the gut,” Stein tells WebMD. These tips can help you protect your digestive health and your overall well-being.

  • Check your meds. Stein and Hanan recommend using medications with care. Talk with your doctor to see if your medications could be causing any digestive symptoms. If you use NSAIDs for pain, work with your doctor to find the lowest effective dose, and be sure to take them with food. Also check with your doctor to make sure you are taking only the medications you need.
  • Stay active. Getting at least 30 minutes of exercise 5 days week can help prevent many age-related health problems. It will also help keep you regular and decrease the risk for colon cancer.
  • Eat more fiber. Foods high in fiber, including fruits and vegetable, whole grains, and beans also tend to be high in nutrients and low in fat. High-fiber foods can help prevent constipation and ease symptoms of diverticulosis.
  • Drink plenty of fluids. Drink plenty of fluids throughout the day. Drink enough so that you don't feel thirsty. If you are taking diuretics, talk with your doctor about ways to manage taking your medication so that you don't become dehydrated.
  • Manage your weight. Maintaining a healthy weight can help prevent many age-related health problems such as heart disease, diabetes, and high blood pressure. Avoiding health problems can reduce the number of medications you need to take, which means less worry about digestive side effects. Limiting the fat in your diet, choosing healthy portions, and choosing whole foods instead of processed foods will all help you manage your weight more easily.
  • Get regular health screenings. Be sure to tell your doctor about any troublesome symptoms and ask about regular screenings.


Ira Hanan, MD, associate professor of medicine at the University of Chicago Medical Center.

G. Richard Locke III, M.D., gastroenterologist with the Mayo Clinic in Rochester, MN.

Ellen Stein, MD, assistant professor of medicine at Johns Hopkins Hospital in Baltimore, MD.

Johns Hopkins Health Alerts: “Your Aging Digestive System.”

Merck Manual: “Effects of Aging on the Digestive System.”

American Gastroenterological Association: “Understanding Constipation.”

National Digestive Diseases Information Clearinghouse: “Constipation.”

Medline Plus: “Fluids and Diuretics.”

National Heart, Lung, and Blood Institute: “How Is High Blood Pressure Treated?” “Diuretics and Heart Failure.”

National Digestive Diseases Clearinghouse: “Diverticulosis and Diverticulitis.”

Z. Marcum. Annals of Long-Term Care: Clinical Care and Aging, 2010; vol. 18, no. 9

National Digestive Diseases Clearinghouse: “What I Need to Know About Colon Polyps.”

CDC: “Physical Activity Guidelines.” “Colorectal Cancer Prevention.” “Fiber: How to Increase the Amount in Your Diet.”

CDC: “Losing Weight.”

Choose My “Let's Eat for the Health of It.”

M. Chait. World Journal of Gastrointestinal Endoscopy, December 16, 2010.

© 2012 WebMD, LLC. All rights reserved.


Diets for Seniors: The Nutrition Advice Every Senior Citizen Needs

How Digestion Works | Johns Hopkins Medicine

The editor of Biblical Archaeology Review, Hershel Shanks, 84, told it straight while dining at the Cosmos Club in Washington, D.C.

“There’s not much written on diets for octogenarians,” he commented casually as the waiter brought him a fruit bowl sans dessert. “I hope I’m doing the right thing.” He was.

But why can’t someone as erudite and research-facile as Shanks find answers to his nutrition questions?

Shanks is unly to glean helpful advice from diet books. An analysis of 12 robust clinical studies across four popular diets (Atkins, Weight Watchers, South Beach, and Zone) didn’t focus on dietary outcomes of particular relevance to elders, nor were the elderly represented in these studies.

Some people reason that it’s unproductive for the elderly to diet. The rationale I’ve heard sounds this, “Reaching one’s 80s and living a vibrant life, that’s success. You can’t improve on that. Besides, who is going to change what they eat in their 80s?” Dr.

Zeke Emanuel took this argument disturbingly further. His essay entitled “Why I Hope to Die at 75,” published in The Atlantic last fall, implies that elder nutrition should not be supported by healthcare dollars.

For Emanuel this was more than personal opinion because he helmed the nation’s healthcare reform.

Following the controversial essay, the American Medical Association Foundation reconsidered, but ultimately upheld, Emanuel as the 2013 recipient of the organization’s prestigious Award for Leadership in Medical Ethics and Professionalism, leaving our nation with lingering questions.

But in practice, doctors are having success extending vibrant lives and changing the refueling habits of their elderly patients. “There’s no upper age limit for obesity medicine,” maintains Lawrence Cheskin, MD a gastroenterologist and Founding Director of the Johns Hopkins Weight Management Center for the past 24 years. He has treated several nonagenarians.

Doctors in various medical specialties are taking a renewed interest in the gastrointestinal tract of their elderly patients. Five interventions which are backed by strong evidence and clinical experience are presented here in order of their geographic appearance along the alimentary tract (gut). I call it the “nutrition takes guts” check-up:

  1. Screen for loss of taste and smell. Sense of smell and taste diminish at variable rates with advanced age, and their loss has recently been identified as a predictor of life expectancy. Loss of smell can be easily assessed with a physical exam, while patients may be more ly to notice and tell their doctor about a diminished sense of taste. Both are important for diet and recognizing thirst. While only some underlying causes such as sinusitis, colds and zinc deficiency can be treated, diagnosing loss of smell and taste are clinically useful even in the absence of treatment. Awareness can be life-saving when accompanied by practical precautions such as upgrading the kitchen smoke detector, looking at expiration dates of refrigerated foods rather than relying on the whiff test, drinking water on a schedule, and flavoring with spices instead of sweeteners. Spices are especially important because they aid digestion, are nutritious (in contrast to artificial sweeteners) and add flavor with fewer calories. Therefore, I recommend those who can’t smell chipotle use it to season their food.
  2. Examine for dental issues. Imagine a meal prepared from a 3-D printer. Such food is quickly becoming available for several applications, including elderly people suffering from dysphagia (difficulty swallowing). 3-D foods look appetizingly the real thing, but dissolve in the mouth as if they are puree. While most elderly patients with dental and swallowing issues don’t need 3-D printed steak, they do need their doctor to examine them for dental problems, which impact overall health. Dental pain makes it harder for the elderly to meet protein requirements. Gum disease predicts vascular disease and heart attacks, although the association is not fully understood. And a red, swollen tongue is an often overlooked sign of vitamin B12 deficiency.
  3. Apply the stomach acid test. During a meal, the stomach’s pH drops to 1, nearly the pH range of battery acid, in order to increase nutrient absorption and foodborne pathogen resistance. Physiologically expensive, stomach acid production wanes during aging and is thought to be why protein requirements increase for the elderly despite a slowing metabolism. Low vitamin B12, anemia, and characteristic nail bed changes point to a decline in stomach acid. Physicians can help patients evaluate the merits of antacids; learn to eat low-sodium fermented vegetables such as sauerkraut, kimchee, and pickled garlic; include vinegar, coffee, and bitters as digestive aids in their diet; and skip the raw bar.
  4. Alkalinize the small intestine through diet. Blood has a pH range of 7.34 to 7.45, which is precisely maintained by the kidneys and lungs. A diet high in refined carbohydrates, meat, and salt generates biologic acids that must be quickly neutralized by the body’s metabolism so as to protect the pH of blood. As kidney and lung function decline with age, an acid-producing diet metabolism doesn’t get balanced as well. The body taps bone calcium reserves and refrains from repairing proteins such as muscle to keep blood at the necessary pH. The loss of bone and muscle tends to be insidious until compounded by minor illness and bed rest because exercise is needed for strong bones. Boosting fruit and vegetable intake and a daily supplement of lime juice, which is biochemically alkalinizing even though it is acidic by pH, or citrate have been shown to protect muscle and bone.
  5. Restore the large intestine’s microbiome through diet. The gut’s microbial workforce, colonic bacteria, diminishes with age, with the elderly having fewer than half the microbes than people half their age. Ongoing research suggests that bulking up stool can help bulk up muscle. Clinical recommendations include hydration, prebiotics (dietary fiber), and probiotics from dietary sources such as cultured dairy. A diet rich in vitamin C and magnesium and magnesium sulfate baths (Epsom salts) may help regularity, especially for symptoms following antibiotic use.

In my experience patient interest is seldom a barrier to accessing nutritional medicine services. A more formidable challenge is reimbursement for both physician visits and the diagnostic tests they order. Dr. Cheskin says reimbursement hasn’t gotten any easier; there is no single checkbox on billing forms. Instead a nutritional assessment requires many screening diagnostic billing codes.

At the D.C. luncheon lecture on health insurance and medical research where I met Mr. Shanks, he stopped me, punctuating the air with his dessert fork. “It’s not about doctors, researchers and the government [health insurance]. Try writing for people. People need to know about this.” And, ultimately, it is the people’s choice.

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Write to Ingrid Kohlstadt at