Summary: Eating a handful of almonds every day increases butyrate production, improves bacterial metabolism and positively affects health.
source: King’s College London
A team of researchers from King’s investigated the influence of whole and ground almonds on the composition of gut microbes.
The study, published today in American Journal of Clinical Nutritionis funded by the Almond Board of California.
The gut microbiome consists of thousands of microorganisms living in the gut. They play a vital role in the digestion of nutrients and can have a positive or negative impact on our health, including the digestive and immune systems.
The mechanisms of how gut microbiomes influence human health are still being explored, but evidence suggests that eating specific types of food can positively affect the types of bacteria in our gut or what they do in our gut.
Researchers recruited 87 healthy adults who were already eating less than the recommended amount of dietary fiber and snacking on typical unhealthy snacks (eg, chocolate, chips).
The participants were divided into three groups: one group replaced their snacks with 56 g of whole almonds per day, another with 56 g of ground almonds per day, and the control group ate energy-matched muffins as a control. The trial lasted four weeks.
“Part of the way the gut microbiota affects human health is through the production of short-chain fatty acids, such as butyrate. These molecules act as a fuel source for cells in the colon, they regulate the absorption of other nutrients in the gut and help balance the immune system,” said lead author Professor Kevin Whelan, Head of Nutritional Sciences
The researchers found that butyrate was significantly higher among people who ate almonds compared to those who consumed the muffins. Butyrate is a short-chain fatty acid that is the main fuel source for the cells lining the colon.
When these cells are functioning effectively, it provides ideal conditions for gut microbes to thrive, for the gut wall to be healthy and not leaky or inflamed, and for nutrients to be absorbed.
No significant difference was seen in transit time – the time it takes for food to move through the intestines – but people who ate whole almonds had an extra 1.5 bowel movements per week compared to the other groups. These findings suggest that eating almonds may also benefit those with constipation.
Tests show that eating whole and ground almonds improves people’s diets, with higher intakes of monounsaturated fatty acids, fiber, potassium and other important nutrients compared to a control group.
Professor Whalen added: “We think these findings suggest that almond consumption may benefit bacterial metabolism in a way that has the potential to impact human health.”
About this diet and microbiome research news
Author: Kevin Whelan
source: King’s College London
Contact: Kevin Whelan – King’s College London
Image: Image is in the public domain
Original research: Free access.
“Effects of almonds and almond processing on gastrointestinal physiology, luminal microbiology and gastrointestinal symptoms: a randomized controlled trial and a chewing study” by Kevin Whelan et al. American Journal of Clinical Nutrition
The effect of almonds and almond processing on gastrointestinal physiology, luminal microbiology and gastrointestinal symptoms: a randomized controlled trial and a chewing study
Almonds contain lipids, fiber, and polyphenols and possess physicochemical properties that influence the bioavailability of nutrients that are hypothesized to influence gut physiology and microbiota.
Investigate the effects of whole almonds and ground almonds (almond meal) on faecal bifidobacteria (primary outcome), gut microbiota composition and transit time.
Healthy adults (n = 87) participated in a 3-arm parallel randomized controlled trial. Participants received whole almonds (56 g/day), ground almonds (56 g/day), or an isocaloric control muffin instead of their usual snacks for 4 weeks. Gut microbiota composition and diversity (16S rRNA gene sequencing), short chain fatty acids (gas chromatography), volatile organic compounds (gas chromatography mass spectrometry), gut transit time (wireless mobile capsule), stool output and intestinal symptoms (7- daily log) were measured at baseline and endpoint. The effect of almond shape on particle size distribution (PSD) and predicted lipid release was measured in a subset (n = 31).
A modified intention-to-treat analysis was performed on 79 participants. There were no significant differences in the abundance of faecal bifidobacteria after consumption of whole almonds (8.7%, SD 7.7%), ground almonds (7.8%, SD 6.9%) or control (13.0%, SD 10 .2%; r = 0.613). Almond consumption (whole and ground) resulted in higher butyrate (24.1 μmol/g, SD 15.0 μmol/g) compared to control (18.2 μmol/g, SD 9.1 μmol/g; p = 0.046). There was no effect of almonds on gut microbiota at the level of type or diversity, gut transit time, stool consistency or bowel symptoms. The form of almonds (whole vs. ground) had no effect on the study results. Ground almonds resulted in significantly lower PSD and higher predicted lipid release (10.4%, SD 1.8%) compared to whole almonds (9.3%, SD 2.0%; p = 0.017).
Almond consumption had a limited effect on gut microbiota composition, but increased butyrate concentrations in adults, suggesting positive changes in microbiota functionality. Almonds can be included in the diet to increase fiber consumption without causing stomach symptoms.