Flatulence, the passing of intestinal gas, often becomes more frequent or noticeable with age. This gas is a normal byproduct of digestion, primarily composed of nitrogen, oxygen, and gasses produced by gut microorganisms. These microbes ferment undigested food particles in the large intestine. While the average person passes gas about 14 times per day, many older adults experience an increase due to a combination of physiological shifts and external factors.
Changes in Digestive Motility
The physical movement of the digestive tract, known as motility, naturally slows down as the body ages, directly impacting gas production and elimination. This slowdown is often attributed to a progressive reduction in the strength and coordination of peristalsis, the involuntary muscle contractions that propel food through the intestines. When transit time through the small and large intestines increases, food waste remains in the colon for longer periods, providing more time for gas-producing bacteria to ferment carbohydrates and fibers.
A reduction in stomach acid production, a condition called hypochlorhydria, becomes more common with advancing age, particularly due to conditions like atrophic gastritis. Stomach acid acts as a protective barrier, limiting the number of bacteria that can migrate from the colon upward into the small intestine. Lower acid levels can therefore contribute to Small Intestinal Bacterial Overgrowth (SIBO), where excess bacteria in the small bowel ferment food too early in the digestive process, leading to increased gas, bloating, and discomfort.
The muscles that control the expulsion of gas are also subject to age-related weakening. The anal sphincters, which regulate the release of gas and stool, can lose tone and become less effective over time. This muscular change can make it more difficult to control the timing and volume of flatulence, contributing to the feeling that gas is passed more spontaneously and less predictably.
Shifts in Gut Microbiota and Enzyme Function
The composition of the gut microbiome—the community of microorganisms living in the intestines—shifts with age, often resulting in a loss of diversity. This change can involve a decrease in certain beneficial bacteria and a relative increase in species that produce a higher volume of gasses like hydrogen and methane during fermentation.
A major factor is the decline in the production of specific digestive enzymes. Most notably, the level of lactase, the enzyme required to break down the milk sugar lactose, decreases in a large portion of the global population after childhood. This acquired lactase deficiency, commonly known as lactose intolerance, means that undigested lactose travels to the colon, where it is aggressively fermented by bacteria, causing significant gas and bloating.
The reduced production of pancreatic enzymes, which help digest fats, proteins, and carbohydrates, can also occur with age. When these macronutrients are not fully broken down in the small intestine, they pass into the large intestine, where they become additional fuel for gas-producing microbes.
External Factors and Medications
External lifestyle factors and common medical treatments heavily influence flatulence in older adults. Many medications frequently prescribed for chronic conditions can have digestive side effects that increase gas. For example, drugs for high blood pressure, certain pain relievers like opioids, and even common antibiotics can disrupt the balance of the gut microbiota or slow intestinal motility, leading to constipation and gas buildup.
Changes in dietary habits are another common influence, as older adults may increase their consumption of high-fiber foods to combat age-related constipation. While fiber is beneficial, a sudden or large increase in fermentable fibers or the consumption of artificial sweeteners, which are difficult to digest, provides extra substrate for gas-producing bacteria.
The volume of gas can also be increased by aerophagia, the act of swallowing excess air. Factors more prevalent in older age, such as wearing ill-fitting dentures, chewing gum, or eating and drinking too rapidly, can cause a person to swallow more air. This swallowed air, primarily nitrogen and oxygen, travels through the digestive tract and is eventually expelled as flatulence.