Is it food intolerance or are you just getting older?

Our bodies like to remind us that we aren’t as young as we used to be. The good news is that our digestive systems aren’t affected by aging as much as the other parts of us [1]. The bad news is that we can’t abuse our stomachs like we used to if we want to maintain the pleasure of eating. Does this mean that we have developed food intolerance? Not necessarily. To see why, let’s first look at the normal gastrointestinal signs of getting older, along with some age-related complications.

Age-related changes in digestion

Age brings with it certain changes in digestive function that some healthy people may notice more than others, including [2]:

  • Decreased lactase production. Older adults are more likely to be lactose intolerant and experience bloating, gas, or diarrhea after eating dairy products.
  • Decreased elasticity and slower emptying of the stomach. Some people cannot eat as much as they used to in one sitting without feeling fullness or bloating.
  • Overgrowth of certain bacteria in the small intestine. Our gut bacteria is mostly confined to the large intestine, and this is normal (although some bacteria are more desirable than others). As we age, the chance of bacterial overgrowth in the small intestine increases, producing pain, bloating, and weight loss.
  • Slowing or weakening of contractions in the large intestine. Constipation is more likely as we age.

If any of these points sound familiar, speak with your doctor to make sure that your symptoms are simply age-related and not part of a more serious problem. Be sure to discuss any signs of small intestinal bacterial overgrowth, because even though you can find plenty of Internet advice about “healing your gut” on your own, this condition may need medical treatment.

Other gastrointestinal symptoms are not caused by aging per se, but by things that go along with age [3], such as:

  • Medications. These can increase or decrease the time it takes for food to pass through us, resulting in either constipation or loose stools.
  • Age-related illnesses. Certain illnesses can also affect the proper functioning of the digestive system.
  • Obesity. Obesity makes heartburn more likely.
  • Continuing bad eating habits. Late-night fast food or too much coffee can cause heartburn and affect intestinal transit time.

In these cases, something as simple as a change in medication could provide much relief. As I said before, talk with your doctor about your concerns.

Relationship with food intolerance

If someone experiences a bad reaction after eating a certain food, it’s easy to understand why they might conclude that they have food intolerance – after all, it’s almost impossible to escape the association between food and digestion. But true food intolerance is a hypersensitivity reaction to food (emphasis on hyper-sensitivity) that most people will not encounter.

Continuing with our original question, are any age-related symptoms actually food intolerance? Well, there are three types of food intolerance [4,5]:

  • Enzymatic food intolerance – when the body does not make enough enzymes to digest or properly use a nutrient, as in lactose intolerance or phenylketonuria.
  • Pharmacological food intolerance – drug-like effects of mostly non-nutritive food chemicals (and the subject of this blog).
  • Toxic reactions – mainly histamine toxicity from spoiling fish (scombroid poisoning)

According to this classification, lactose intolerance is a type of food intolerance, but the other age-related digestive symptoms are not. This is an important distinction to make with regards to how we think about (and act on) our current state of health – in other words, do we continue to view ourselves as “normal” for our age, or do we start to feel like we have a “problem”?

What does this mean?

When food-related symptoms occur more frequently with age, this does not necessary mean that we have developed a medical problem – food intolerance – that needs to be treated by completely avoiding certain foods. It might just mean the we need to change our eating habits, like when we eat, how much we eat, and how much we can expect to indulge. For example, an adult with lactose intolerance may still be able to eat small amounts of dairy products (like yogurt) throughout the day, but they shouldn’t expect to go out after a soccer game and eat an ice cream sundae on an empty stomach like the rest of the kids. That said, if you are experiencing any of the symptoms mentioned in this article, see your doctor before attributing them to age.

Last updated January 14, 2015

© 2014-5 Anna (Laurie) Laforest. All rights reserved.
Photo © Can Stock Photo Inc. – Food intolerance resource with a scientific twist


1. Russell RM. Changes in gastrointestinal function attributed to aging. Am J Clin Nutr. 1992 Jun 1;55(6):1203S–1207S. PubMed

2. Effects of Aging on the Digestive System: Biology of the Digestive System: Merck Manual Home Edition [Internet]. [cited 2014 Apr 20]. Available from:

3. Karen E. Hall, Wiley JW. Age-Associated Changes in Gastrointestinal Function. In: Hazzard W, et al. editors. Principles of Geriatric Medicine and Gerontology. 4th ed. New York: Mcgraw-Hill; 1998. p. 835–42.

4. Boyce JA, Assa’ad A, Burks AW, Jones SM, Sampson HA, Wood RA, et al. Guidelines for the Diagnosis and Management of Food Allergy in the United States: Summary of the NIAID-Sponsored Expert Panel Report. J Allergy Clin Immunol. 2010 Dec;126(6):1105–18.

5. Bruijnzeel-Koomen C, Ortolani C, Aas K, Bindslev-Jensen C, Björkstén B, Moneret-Vautrin D, et al. Adverse reactions to food. Allergy. 1995;50(8):623–35. PubMed