Gut Health 101
Your “gut” or microbiome is a bustling metropolis of bacteria, fungi, parasites, and viruses who happily exist together in our small and large intestines. These tiny organisms carry out many helpful jobs, not limited to digesting vitamins, keeping us regular, and supporting our immune systems. But our gut village may be thrown out of balance by things like:- A diet low in plant-based foods
- Stress
- Use of NSAID pain medications like aspirin or ibuprofen
- Antibiotic use
Why Gut Health Matters
Some people assume that if they don’t have noticeable digestive issues, they don’t need to worry about their gut health. Not so! It is true that when our gut is overrun with “bad” bacteria, we may experience diarrhea, constipation, or bloating. However, people with unbalanced microbiomes don’t always have digestive symptoms but are still at risk for certain cancers, obesity, or infections.1Walnuts and Good Gut Bacteria
Walnuts are known as part of a heart-healthy diet, but did you know that eating walnuts may positively change your microbiome? Walnuts contain indigestible fibers called prebiotics, which are a food source for good bacteria (probiotics). Studies with adults have already shown promising results. For example:- A randomized control cross-over trial1 of nearly 200 healthy adults assigned people to eat a daily serving of walnuts (1.5 ounces) for eight weeks and compared what happened when those same people had a nut-free diet for another eight weeks. The walnut group experienced both a significant increase in a variety of healthy bacteria and a significant reduction in unhealthy bacteria.
- Another smaller, but highly controlled, randomized control trial of 18 healthy adults2 found that, compared to a control group, people who ate a handful of walnuts for three weeks gained nearly twice as much gut bacteria Roseburia, known for its positive role in human immune function.
Gut Health and Stomach Cancer Risk
Non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, are medications commonly taken for chronic pain. Unfortunately, nearly 1 in 6 patients using NSAIDs long-term will develop a stomach ulcer,3 especially if their gut is home to a lousy bacterium called Helicobacter pylori (H. pylori), a known precursor to stomach cancer. Due to an interest in non-drug approaches to combat increasingly antibiotic-resistant H. pylori, scientists have turned their attention to animal nutrition studies. These studies help researchers see if feeding a certain diet to animals changes the course of a potential disease and informs new questions to answer in future medical research with humans. For example, one group of recently published studies using mice models found evidence that a walnut-rich diet protected against gut damage from NSAIDs4 and boosted cancer-fighting proteins and anti-inflammatory actions in the gut5 that are thought to protect against H. pylori infection. While animal studies are just the beginning, these findings will likely lead to future trials in animal and human models to further explore walnuts’ role as a functional food in gut health. Top gut health takeaways:- Gut bacteria and other microbes can be protective or harmful.
- We are what we eat. The quality of our diet seems to directly impact our microbiome.
- A daily serving of walnuts has been associated with positive changes in gut bacteria. This research area is ongoing, and more study is needed to determine how eating walnuts may impact humans’ gut health over time. However, the research is promising.
1Bamberger C, Rossmeier A, Lechner K, Wu L, Waldmann E, Fischer S, Stark RG, Altenhofer J, Henze K, Parhofer KG. A walnut-enriched diet affects gut microbiome in healthy caucasian subjects: a randomized, controlled trial. Nutrients. 2018 Feb;10(2):244.
2Holscher HD, Guetterman HM, Swanson KS, An R, Matthan NR, Lichtenstein AH, Novotny JA, Baer DJ. Walnut consumption alters the gastrointestinal microbiota, microbially derived secondary bile acids, and health markers in healthy adults: a randomized controlled trial. J Nutr. 2018 May 3. doi: 10.1093/jn/nxy004.
3Non-steroidal Anti-inflammatory Drugs, MedicineNet. https://www.medicinenet.com/nonsteroidal_anti-inflammatory_drugs_and_ulcers/article.htm. Accessed October 13, 2020.
4An JM, Kim EH, Lee H, Lee HJ, Hahm KB. Dietary walnut as food factor to rescue from NSAID-induced gastrointestinal mucosal damages. Arch Biochem Biophys. 2020 Aug 15;689:108466. doi: 10.1016/j.abb.2020.108466. Epub 2020 Jun 23. PMID: 32590067.
5Park JM, Han YM, Park YJ, Hahm KB. Dietary intake of walnut prevented Helicobacter pylori-associated gastric cancer through rejuvenation of chronic atrophic gastritis. Journal of clinical biochemistry and nutrition. 2021;68(1):37-50.