Munching on almonds improves gut health
Summary: Daily consumption of a handful of almonds increases the production of butyrate, improves the metabolism of bacteria and has a positive effect on health.
Source: King’s College London
A team of researchers from King’s investigated the effect of whole and ground almonds on the composition of gut microbes.
The study, published today in American Journal of Clinical Nutritionfunded by the Almond Board of California.
The gut microbiome consists of thousands of microorganisms that live in the gut. They play a vital role in the digestion of nutrients and can have a positive or negative effect on our health, including our digestive and immune systems.
The mechanisms by which the gut microbiome affects human health are still being researched, but evidence suggests that eating certain types of food can positively affect the types of bacteria in our guts or what they do in our guts.
Researchers recruited 87 healthy adults who were already eating less than the recommended amount of dietary fiber and who were snacking on typical unhealthy snacks (eg, chocolate, chips).
The participants were divided into three groups: one group exchanged snacks for 56 g of whole almonds per day, the other for 56 g of ground almonds per day, and the control group ate energy-matched muffins as a control group. 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, 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 those who ate almonds compared to those who consumed cookies. Butyrate is a short-chain fatty acid that is the main fuel source for the cells lining the large intestine.
When these cells function effectively, it provides ideal conditions for the development of intestinal microbes, for the intestinal wall to be strong and not leaky or inflamed, and for nutrients to be absorbed.
No significant difference was seen in bowel transit time – the time it takes for food to pass all the way through the intestines – however those eating whole almonds had an extra 1.5 bowel movements per week compared to the other groups. These findings suggest that consuming almonds may also benefit those with constipation.
Testing showed that consumption of whole and ground almonds improved people’s nutrition, as they had a higher intake of monosaturated fatty acids, fiber, potassium and other important nutrients compared to the control group.
Professor Whelan added: “We think these findings suggest that eating almonds may benefit bacterial metabolism in a way that has the potential to affect human health.”
About this diet and microbiome research news
Original Research: Open access.
“Effects of almonds and almond processing on gastrointestinal physiology, luminal microbiology and gastrointestinal symptoms: a randomized controlled trial and a chewing study” Kevin Whelan et al. American Journal of Clinical Nutrition
Effects 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, which are hypothesized to influence gut physiology and microbiota.
Investigate the effect of whole almonds and ground almonds (almond flour) on faecal bifidobacteria (primary outcome), gut microbiota composition and transit time.
Healthy adults (n = 87) participated in a parallel, 3-arm randomized controlled trial. Participants received whole almonds (56 g/d), ground almonds (56 g/d), 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 bowel symptoms (7-day diary) they were measured at the starting and ending points. The effect of almond shape on particle size distribution (PSD) and predicted lipid release was measured in a subgroup (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%); q = 0.613). Almond consumption (whole and ground) resulted in 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 levels or diversity, gut transit time, stool consistency or bowel symptoms. The shape of the 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 has a limited effect on the composition of the intestinal microbiota, but increases the concentration of butyrate in adults, which indicates positive changes in the functionality of the microbiota. Almonds can be included in the diet to increase fiber consumption without causing bowel symptoms.
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