How Beneficial is the Use of Probiotic Supplements for the Aging Gut?

Siobhán Cusack; Marcus J Claesson; Paul W O'Toole


Aging Health. 2011;7(2):179-186. 

In This Article

Intestinal Health & Aging

There are many specific age-related dietary and physiological changes that impact on the function and efficacy of the intestine and aging health. Diet, in particular, can influence health status in later life. Obesity and malnutrition are common factors of aging, influencing distinct but equally deleterious health outcomes. Diet has more recently become a focus of interest owing to its involvement in shaping the composition of the human intestinal microbiota. For example, short chain fatty acids (SCFA), formed primarily by fermentation of indigestible dietary components by microorganisms in the large intestine,[9] support the growth of bifidobacteria that help protect against infection and inflammation.[10]

With increasing age comes a reduction in the capacity of taste and smell. Combined with decreased dentition, muscle mass, the use of frequently ill-fitting dentures and swallowing difficulties commonly seen in older age, the type and quantities of food eaten tends to be a narrow, and the diet becomes more nutritionally imbalanced. In addition, an age-related reduction in gastric acid production, coupled with increased basal gastric inflammation, can lead to lower micronutrient absorption from the diet. Finally, once ingested, the time taken for food to transit through the aging intestine increases (owing to age-related changes in gastrointestinal function and the intestinal bacteria).[2] Compounded further by a generally decreased level of physical activity in older age and increased fecal retention, there is a shift from beneficial saccharolytic fermentation towards increased levels of putrefaction that can lead to a buildup of deleterious putrefaction by-products such as ammonia and phenols.[3]

The consequence of age-related intestinal changes, apart from the very obvious common discomforts of bloating and constipation, is often a general shift in dominant bacterial species.[11] Furthermore, immunosenescence, the progressive decline in the integrity of both the innate and adaptive immune system with increasing age, is characterized by an imbalance between inflammatory and anti-inflammatory processes. In addition to affecting the composition of the microbiota in the aging intestine, immunosenescence can lead to a greater susceptibility to infection, malignancy, autoimmunity, a decreased response to vaccination and delayed wound healing.[12]

We believe that probiotics are a vital tool in the battle to overcome imbalance and restore the health-promoting composition and function of the microbiota in older age, promoting and maintaining health and reducing the impact of age-related disease. To support this contention, we will discuss in more detail the composition, function and alteration of the human intestinal microbiota.


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