Skip to main content

Almond Consumption May Benefit Some Gut Microbiota Functionality, Study Finds


What you need to know about gut health and almonds.

A study from King’s College London1 set out to determine the impact whole almonds and ground almonds (almond flour) have on the composition of gut microbiota, gut microbiota diversity and gut transit time.

Led by Professor Kevin Whelan, the study found that consuming almonds significantly increases butyrate, a type of beneficial short-chain fatty acid (SCFA), in the colon. Butyrate, which is produced by microbes in the gut when they digest fiber, is the primary fuel source for colonocytes, the cells that line the colon, and may play a role in multiple processes related to human health, including improving sleep quality and fighting inflammation, and has been associated with a lower risk of colon cancer.2,3 The study also found that almond consumption significantly increases stool output, which is associated with a well-functioning gastrointestinal system.

How do almonds impact your gut health?

Here’s everything you need to know about this new study:

Study Participants:
The study comprised healthy adult volunteers (75 females, 12 males), average age 27.5 years, who were regular snackers, and who were consuming a typical diet that was lower in fiber than recommended.

Study Design:
Participants were randomly assigned to a group, each comprised 29 participants; group one received 56 g/day (about 2 oz./day) of whole almonds, group two 56 g/day (about 2 oz./day) of ground almonds (almond flour), and the control group ate energy-matched snack muffins (two per day). Participants were required to eat their study snacks instead of customary snacks, and they did this twice a day for four weeks. They drank at least 100 mL water with each snack.

Study Results:
The study found that participants who consumed almonds experienced significant increases in butyrate as well as increased stool frequency. Almonds were well tolerated and did not lead to gastrointestinal symptoms, which indicates almond consumption may be a way to increase fiber without causing any adverse effects. This is suggestive of positive alterations to microbiota functionality.

Looking Into the Future of Almonds and Gut Health Research

Given the promising findings, more research is in the works to look at the impact almonds have on gut health and to help improve our knowledge in the area.

Feeding Your Gut with Nutrients

The research makes a clear correlation between the many nutrients contained in almonds and their potential role in helping improve and maintain gut health. One serving (28 g) of almonds provides 4 g fiber and 15 essential nutrients, including: 77 mg (20%DV) magnesium, 210 mg (4%DV) potassium, and 7.27 mg (50%DV) vitamin E, making them a nutrient-rich snack.

Study at-a-Glance

The Study

  • Researchers explored the prebiotic effect of almonds and the potential impact almond processing had on this effect in a free-living, 4-week, 3-arm, parallel-design randomized controlled trial.
  • Eighty-seven healthy adults participated and received either 56 g/day whole almonds, 56 g/day ground almonds, or an isocaloric snack muffin as the control.
  • Baseline and endpoint measures included gut microbiota composition and diversity, short-chain fatty acids, volatile organic compounds (VOCs), gut transit time, stool output, and gut symptoms (n=87). A subgroup (n=31) was measured for the impact of almond form, ground or whole, on particle size distribution (PSD) along with predicted lipid release.


  • Researchers observed no significant differences in the abundance of fecal bifidobacteria following consumption of either form of almond or the control snack. Almond consumers (both ground and whole almonds), had higher butyrate (24.1 μmol/g; SD 15.0 μmol/g) compared to the control (18.2 μmol/g, SD 9.1 μmol/g; p=0.046).
  • There was no effect of almonds on gut microbiota at the phylum level or diversity, gut transit time, stool consistency, or gut symptoms. Three VOCs increased following almond consumption compared to control muffins, but this change was not statistically significant.
  • Ground almonds resulted in significantly smaller PSD and higher predicted lipid release (10.4%, SD 1.8%) in comparison to whole almonds (9.3%, SD 2.0%; p=0.017). • Of the subgroup participating in the mastication study, analysis of PSD demonstrated a significant interaction between whole almonds and the particle size on PSD; however, commercially ground almonds did not differ meaningfully in their nutrient bioaccessibility from whole almonds.
  • Post-hoc testing showed whole almond participants had higher intakes of monounsaturated fatty acids, total fiber, potassium, along with other nutrients when compared to the control participants. Similarly, ground almond consumers had higher intakes of monounsaturated fatty acids, total fiber, and other micronutrients.


  • Participants who consumed almonds experienced small but significant differences in stool frequency as well as significant increases in butyrate in the colon. Researchers indicate that these findings suggest positive alterations to gut microbiota functionality. The impact of almond consumption on bacterial metabolism has the potential to influence human health.
  • These results have inspired thinking regarding how almonds may benefit older adults as well as those with constipation, as these populations are known to have lower levels of bifidobacteria than healthy, young adults as well as those without constipation.

1 Creedon, A. C., Dimidi, E., Hung, E. S., Rossi, M., Probert, C., Grassby, T., Miguens-Blanco, J., Marchesi, J. R., Scott, S. M., Berry, S. E., & Whelan, K. (2022). The impact of almonds and almond processing on gastrointestinal physiology, luminal microbiology and gastrointestinal symptoms: a randomized controlled trial and mastication study. American Journal of Clinical Nutrition, nqac265.


Koh, A., De Vadder, F., Kovatcheva-Datchary, P., & Backhed, F. (2016). From dietary fiber to host physiology: short-chain fatty acids as key bacterial metabolites. Cell, 165(6), 1332-1345. doi: 10.1016/j.cell.2016.05.0413


Szentirmai, E., Millican, N. S., Massie, A. R., & Kapas, L. (2019). Butyrate, a metabolite of intestinal bacteria, enhances sleep. Scientific Reports, 9:7035, 1-9.