July 2015 Issue

Digestive Wellness: The Link Between Aging and Digestive Disorders
By Kate Scarlata, RDN, LDN
Today's Dietitian
Vol. 17 No. 7 P. 12

There's no doubt that the aging human body undergoes numerous changes. Age-related health conditions include macular degeneration, osteoarthritis, hypertension, and neuromuscular and anatomical changes in the gastrointestinal (GI) tract. As we grow older, onset of digestive symptoms such as dyspepsia related to gastroesophageal reflux disease (GERD), diarrhea, constipation, bloating, and flatulence become multifactorial. Oral health, lifestyle and diet, medication use, motility or anatomical alterations, and hormonal shifts are among the contributing factors.

Oral Health
Poor oral health can contribute to various GI symptoms. For example, dental decay and changes in dentition can disrupt nutritional status and cause constipation. Tooth loss is associated with age-related decline in bone mass and calcium content in the skeleton. Soft, easy-to-process foods are preferable for the edentulous, but they often lack fiber, which can impact colonic transit, as many fibers have a laxative effect.1 In addition, inadequate mastication can hinder digestion. Adequate mastication, which increases the surface area of food in the mouth to allow enzymes to efficiently break it down, enhances digestion, and this process begins with the salivary enzyme amylase. Moreover, a decline in basal salivary gland secretion appears to occur with normal aging and therefore may impact digestion.2,3

Lifestyle and GI Consequences
In addition to oral health, a decline in physical activity, alcohol intake, and stress can play both an indirect and direct role in exacerbating GI symptoms. More specifically, a sedentary lifestyle, excess alcohol intake, and overeating can worsen GI symptoms or create a new health issue that disrupts GI function or requires medications that cause GI side effects.

A sedentary lifestyle coupled with a slower metabolism often leads to weight gain in middle age. Overweight and obesity increases diabetes risk, and diabetes can cause a decrease in GI motility, resulting in gastroparesis. Moreover, additional weight puts pressure on aging joints, which can further inhibit exercise. The associated joint pain resulting from excess weight may lead to frequent use of NSAIDs, and both weight gain and NSAIDs can exacerbate GI issues such as GERD and gastritis.4,5 Sue Kelly, MD, a gastroenterologist at Beth Israel Deaconess Medical Center in Boston, says, "Obesity is the number one chronic disease. One hundred forty six billion dollars are spent annually on treating obesity-related chronic diseases including GERD. Frequent large meals, eating before bedtime, alcohol use, along with insufficient exercise, contribute to GERD risk." Caffeine use also may worsen the condition. GERD occurs when the lower esophageal sphincter doesn't close properly, allowing acid from the stomach to rise to the esophagus. Symptoms include indigestion, burping, bloating, and heartburn.

Other symptoms of GERD that are prevalent in 35% of individuals aged 50 to 79 include dysphagia, and regurgitation.6 Stress can contribute to greater alcohol consumption, which can further aggravate GERD symptoms, and increase the risk of diverticulitis, a condition that presents with abdominal pain, alteration in bowel habits, and fever resulting from inflamed or infected small sacs or pouches, called diverticula, that have formed in the lining of the large intestine.7

Medication Side Effects
Several medications also induce GI symptoms. NSAIDs are associated with a higher risk of GI mucosal injury–associated gastritis. Geriatric patients are the heaviest users of NSAIDs because of the pain and discomfort linked with osteoarthritic changes.2 Drug-induced GI villous atrophy, the flattening and erosion of the absorptive areas of the small intestine, has been described with the use of Imuran, methotrexate, neomycin, and olmesartan, which can cause severe bloating, distention, change in bowel habits, and malnutrition.8 Metformin, a commonly prescribed oral antidiabetes drug, can cause nausea, vomiting, dyspepsia, and diarrhea. Narcotics or neuroleptic medications can lead to a decline in colonic transit contributing to constipation. Proton pump inhibitors may promote small intestinal bacterial overgrowth (SIBO) by minimizing gastric acid, a key antibacterial barrier in the small bowel. SIBO is a condition in which abnormal amounts of bacteria overgrow in the small bowel, resulting in gas, bloating, and changes in bowel habits.

Anatomical and Neuromotor GI Changes
Physical or anatomical changes in older people due to muscular atrophy also are common. The GI tract comprises a series of muscular organs. While coordinated movements of these muscles contribute to normal peristalsis, aging can weaken the muscles, and circumstantial events, such as pelvic floor damage due to difficult childbirth, potentially can culminate in the onset of GI symptoms, including constipation and bloating. Neuromotor changes in how nerves impact motility, due to neurodegeneration, can occur in the GI tract during aging, which can contribute to dysphagia, GERD, and constipation.9 There's an increased frequency of slow transit or motility-related issues, such as delayed gastric emptying and constipation with aging.10

Another GI disease that's common in middle-aged Americans is diverticulosis, a condition in which the diverticula within the lining of the large intestine aren't infected or inflamed but may cause constipation, diarrhea, bloating, cramping, or pain in the lower abdomen. It's estimated that by age 50, one-third of Americans will have some diverticula and by age 80, nearly two-thirds will have diverticular disease.2 Studies have found links between diverticular disease and obesity, lack of exercise, smoking, and certain medications, including NSAIDs. Alcohol intake is a risk factor for diverticulosis and perhaps is the reason this condition is more prevalent in Westernized countries, although heavy intake of highly processed, low-fiber foods also has been implicated.7

Pelvic Floor Disorders
Anorectal dyssynergy or paradoxical anal contractions can lead to incomplete emptying of the rectum. Diabetes can further contribute to constipation due to delayed transit times secondary to autonomic neuropathy. Age-related changes in the physical structure and function of the pelvic floor likely contribute to constipation and fecal incontinence.11 Satish S. C. Rao, MD, renowned motility expert and gastroenterologist at Georgia Regents University in Augusta, Georgia, says, "Pelvic floor disorders encompass many problems that include dyssynergic defecation, rectal prolapse, excessive perineal descent, fecal incontinence, and others. They affect 20% of the population and profoundly affect quality of life, particularly in the elderly. Recognizing the problem, defining the underlying mechanisms, and providing appropriate treatments are cornerstones for successful management. This requires a multidisciplinary approach involving gastroenterologists, registered dietitians, biofeedback therapists, and motility labs."

Diarrhea can result from foodborne illness, antibiotic use, fecal impaction, colon cancer, carbohydrate malabsorption, SIBO, or overproduction of bile acid.12 Ninety percent of colon cancers occur in people aged 50 or older.2 Celiac disease is increasing in the elderly population. However, GI symptoms associated with celiac disease are subtler in older individuals.13 Food intolerances can occur at any age and should be considered if diarrhea is present.

Lactose Intolerance
Lactose intolerance also increases with advanced age, and in one study it was noted to occur in 50% of elderly subjects. Of those with lactose intolerance, 90% presented with SIBO. Eradication of the bacterial overgrowth corrected the lactose malabsorption, revealing the role of microbes in this condition.14

Fecal Incontinence
Fecal incontinence may occur due to pelvic floor dysfunction, which may develop due to obstetrical injury or with decreased rectal compliance, which can accompany aging. Fecal incontinence is common in middle age and also may occur due to chronic constipation, diarrhea, or chronic diseases such as multiple sclerosis or diabetes. A study from the University of North Carolina found that fecal incontinence prevalence was similar in men and women and increased with age, and noted that 15% of those aged 70 and older experienced fecal incontinence on a monthly basis.15

Hormone Changes
In women, GI symptoms often are exacerbated during menses and early menopause, suggesting that a decline in the ovarian hormones estrogen and progesterone may play a role. Whether this is a direct effect of hormone withdrawal on motility or an immune-related mechanism needs to be determined.16 Diane McGrory, MD, a gynecologist and clinical instructor at Harvard Medical School and Newton-Wellesley Hospital, says, "Women often complain of abdominal bloating, increased gas, and increased abdominal fat in menopause. Some theorize that lower estrogen levels decrease bowel motility through changes in neurotransmitters. As women age, their abdominal muscles weaken, and there's more abdominal bulge after eating. Abdominal bloating also is a symptom of ovarian cancer, so if the symptoms don't improve by eating smaller meals and increasing exercise, then further investigation by a gynecologist or primary care physician should be initiated."

Nutritional Interventions
Diet can help manage GI symptoms associated with aging. Reducing meal size and intake of high-fat foods, and modifying caffeine and alcohol consumption can reduce GERD symptoms. Weight and stress management are other ways to address GI symptoms related to GERD.

The new and emerging low-FODMAP diet, an eating pattern reduced in commonly malabsorbed short-chain carbohydrates, can decrease gas and bloating related to functional gut disorders.17 Further study is underway to determine the impact of a low-FODMAP diet on fecal incontinence.

In addition, minimizing excess weight gain and the stress it places on aging joints potentially can lead to reduced use of NSAIDs. Dietitians can suggest alternative ways to reduce stress to clients and patients such as walking, meditation, or a warm bath rather than relying on alcohol as a means to alleviate tension. Reducing alcohol consumption may lower the risk of diverticulitis and GERD. RDs can encourage clients to maintain adequate fluid and fiber intake to hasten colonic transit, and choose fiber with the most evidence basis to relieve constipation, such as psyllium fiber, rather than rapidly fermentable fibers, such as chicory root or inulin, if gas and bloating are troubling symptoms.1

— Kate Scarlata, RDN, LDN, is a Boston-based dietitian in private practice and the coauthor of 21-Day Tummy, a New York Times bestseller.

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