New study confirms genetic link between gut health and Alzheimer’s disease

A study shows a relationship between gut health and Alzheimer’s and genetic overlap in several other gastrointestinal tract disorders

Over time, we continue to learn more about the gut microbiome’s ability to contribute to or detract from our health and wellness. Research has implicated the gut for its role in conditions such as obesity, type 2 diabetes, fatty liver disease, intestinal bowel disease, various forms of cancer, the gut-brain axis and other gut-body communications. What is often still unclear is the exact connection that exists between gut health and Alzheimer’s or other diseases.

One new study provides greater clarity in this area, reporting that there is a connection or overlap in the genes of people who have gastrointestinal disorders and those who have Alzheimer’s disease.

Genetic connection between the gut and Alzheimer’s disease

This study was published in the Communications Biology journal on July 18, 2022, and involved a comprehensive review of more than 450,000 samples collected via numerous different methods (databases, repositories, and large research groups). Because they used such a large sample size, researchers were able to detect genetic variants associated with even the smallest of effects.

Through cross-trait meta-analysis, several loci were identified as existing in both people with Alzheimer’s and people with gastroesophageal reflux disease (GERD) or peptic ulcer disease (PUD). Among the loci were PDE4B, BRINP3, ATG16L1, SEMA3F, HLA-DRA, SCARA3, MTSS2, PHB, and TOMM40. Results were reinforced by gene-based analyses and colocalization, the latter of which is when a locus has genetic factors shared between at least two traits.

This study also noted a genetic overlap in several other gastrointestinal tract disorders and Alzheimer’s disease, namely gastritis-duodenitis, irritable bowel syndrome, and diverticulosis. No overlap was found between Alzheimer’s and inflammatory bowel disease.

While these findings can’t provide a causal pathway, they do provide greater insight into the gut’s relationship with brain health. This is an area of research that is incredibly complex, in part, because the gut microbiome is impacted by so many different factors that can also affect Alzheimer’s.

Factors affecting the health of the gut

In addition to genetics, a 2020 review article published in Frontiers in Cellular and Infection Microbiology shares that the gut microbiome is “highly sensitive” to external factors such as diet, not getting enough sleep, being exposed to constant noise, and living a sedentary lifestyle. These are all also risk factors in the development of Alzheimer’s disease.

Because so many factors are at play in each, it can be difficult to identify which ones may be causes, which may be effects, and which are merely coincidences. By learning more about the genetic links that exist, it may become easier to make these determinations as research in this area progresses.

Until we know more, there’s no downside in taking steps to improve gut health. And there are several ways to go about achieving this goal.

How to improve the gut

One strategy is to eat a diet rich in flavonoids. Research has found that flavonoids help prevent inflammation in the gastrointestinal tract, both directly and indirectly. These bioactive ingredients can be found in fruits and vegetables, as well as nuts, legumes, and tea.

Another way to improve gut health is by taking prebiotics, probiotics, and polyphenols. Studies report that all three of these functional food components help modulate gut health, also benefitting overall well-being:

• Prebiotics are typically high in fiber and support the growth of healthy gut bacteria.
• Probiotics are live cultures that help strengthen or improve the gut’s “good” bacteria.
• Polyphenols are plant food compounds such as flavonoids and phenolic acid that further support gut health.

Getting enough sleep is also important for a healthy gut. In an article in Sleep Medicine Reviews, authors from the University of Alberta, Edmonton report that sleep fragmentation and short sleep duration both can negatively impact gut bacteria composition. So too does experiencing persistent jet lag, following a diet that contributes to obesity, and other factors that can throw off the circadian rhythm.

Interestingly, this research also suggests that taking probiotics may help improve sleep quality. So, making changes to improve gut health in one way may provide benefits in others such as the relationship between gut health and Alzheimer’s — and may provide patient benefits that support a healthier gut microbiome and health in general.