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Why Do Some People Struggle More With Gut Issues?

A Nutrigenomics and Hormonal Perspective


Digestive symptoms such as bloating, abdominal discomfort, and changes in bowel habits are common. Many people make dietary changes but still feel that their symptoms persist or fluctuate without a clear reason.


One explanation is that gut health is not driven by diet alone, and in practice, symptoms are often influenced by a combination of:

  • gut motility (how well the gut moves)

  • immune and inflammatory responses

  • microbial activity

  • hormone fluctuations

  • and individual genetic differences


Understanding how these factors interact may help explain why some people are more prone to ongoing digestive issues than others.



It’s Not Just About What You Eat


Although symptoms show up in the digestive system, they are often driven by processes involving the nervous system, immune system, liver, and endocrine (hormonal) system. This is why two people can eat similar diets and have very different digestive responses.


Conditions such as irritable bowel syndrome (IBS) are now more and more recognised as disorders of gut–brain interaction, involving dysregulation across multiple systems rather than a single cause.


Key Factors That Can Influence Gut Symptoms


1. Gut Motility and Bacterial Overgrowth


Normal gut function relies on coordinated movement to keep food and bacteria moving in the right direction.


When this process slows, it can contribute to:

  • bloating

  • constipation

  • and, in some cases, bacterial overgrowth in the small intestine (often referred to as SIBO or intestinal methanogen overgrowth, IMO)


Hormones also play a role here:

  • Progesterone is associated with slower gut movement, which can contribute to constipation.

  • This may explain why symptoms fluctuate across the menstrual cycle or during hormonal transitions.


2. Histamine, Mast Cells, and Immune Activity


Histamine is involved in digestion and immune signalling, but in excess it can contribute to symptoms such as:

  • bloating

  • diarrhoea

  • headaches, flushing, or skin reactions


Some individuals may have a reduced capacity to break histamine down. This is often multifactorial and can be influenced by both genetics and gut health itself. In some cases, symptoms may overlap with increased mast cell activity within the gut.


Hormonal interactions are also relevant:

  • Oestrogen can increase histamine activity and mast cell responsiveness.

  • This may contribute to cyclical or fluctuating symptoms.


3. Microbial Balance and Fermentation


Gut bacteria play a key role in digestion, particularly in fermenting carbohydrates. In some individuals, symptoms may relate to:


  • imbalance in the large intestine

  • bacterial overgrowth in the small intestine

  • or increased gas production from fermentation


Reducing highly fermentable carbohydrates can help reduce symptoms in some cases, particularly bloating, although this is typically a short-term strategy.


In terms of microbiome support:


  • In the research, probiotics show mixed results, with benefits varying by strain and individual.

  • Prebiotics may support microbial function, although tolerance varies and they can exacerbate symptoms in some individuals.


4. Hormones and Gut Function


Hormones have direct effects on digestion:

  • Oestrogen influences gut sensitivity, bile flow, and microbial balance.

  • Progesterone can slow gut transit.


At the same time, the gut plays a role in hormone metabolism:

  • Gut bacteria contribute to the metabolism and recirculation of oestrogen.


This creates a two-way relationship between gut health and hormonal balance, which is particularly relevant during phases such as perimenopause.


5. Genetic Differences and Individual Response


Genetic variation does not directly “cause” gut symptoms, but it can influence how the body responds to stressors.


For example, differences in genes involved in:

  • inflammation

  • histamine breakdown

  • detoxification processes

  • and neurotransmitter metabolism


may affect:

  • symptom susceptibility

  • response to dietary changes

  • tolerance to supplements or interventions


This helps explain why a strategy that works well for one person may not work for another.


Why Symptoms Can Persist


Ongoing digestive symptoms are rarely due to a single issue. More often, they reflect a combination of:


  • motility changes

  • microbial imbalance

  • immune activation

  • hormonal fluctuations

  • and underlying susceptibility


This complexity is one reason why a standardised approach to gut health does not always lead to long-term improvement.


In Conclusion


Looking beyond diet towards gut function, hormones, and individual variability can help create a more targeted and effective approach to digestive health.


Nutrigenomics testing can be used as part of a broader clinical assessment to explore individual patterns in more detail, where appropriate. If you are interested in the types of testing available, click here or please feel free to get in touch.


References:

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  4. Kim YS, Kim N. Sex-Gender Differences in Irritable Bowel Syndrome. J Neurogastroenterol Motil. 2018 Oct 1;24(4):544-558. doi: 10.5056/jnm18082. PMID: 30347934; PMCID: PMC6175559.

  5. Ramsay DB, Stephen S, Borum M, Voltaggio L, Doman DB. Mast cells in gastrointestinal disease. Gastroenterol Hepatol (N Y). 2010 Dec;6(12):772-7. PMID: 21301631; PMCID: PMC3033552.

  6. Wilson B, Rossi M, Dimidi E, Whelan K. Prebiotics in irritable bowel syndrome and other functional bowel disorders in adults: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2019 Apr 1;109(4):1098-1111. doi: 10.1093/ajcn/nqy376. PMID: 30949662.

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