Almonds are highly nutritious, and a bit of an oddity: They are high in fat but can reduce cholesterol and promote weight loss.

Like eggs, they are often described as a perfect food.

New research investigates the part of almonds that isn’t digested as food; the insoluble fibre and its effects on gut health and the microbes that support our digestive and immune systems.

Researchers from King’s College London found that almond consumption have a limited impact on gut microbiota composition – the balance of healthy and unhealthy bacteria.

Almonds make gut bacteria work better

Instead, they found that the insoluble dietary fibre found in almonds, when broken down by healthy microbes, increases the concentration of a short-chain fatty acid called butyrate – which is being hailed in some health literature as the next big thing.

There’s plenty of “next big things” in gut health, because it’s an area of study that throws up new discoveries just about every week.

And the butyrate and almonds relationship is an important one.

As the King’s researchers conclude, this increase in butyrate suggests “positive alterations to microbiota functionality”.

In other words, it helps the germs in our gut to work better.

Another key finding was that almonds, as opposed to other sources of fibre, “can be incorporated into the diet to increase fibre consumption without triggering gut symptoms”.

This is because fibre is a tricky thing, especially for people with sensitive guts – too little leaves you prone to serious health issues, too much can trigger a literal blowout.

Almonds are both healthy and benign.

The study

The 87 participants were “healthy adults” who were routinely eating less than the recommended amount of dietary fibre and who snacked on unhealthy foods such as cookies, chocolate and potato chips.

They were split into three groups: One group swapped their snacks for 56 grams of whole almonds a day, another for 56 grams of ground almonds a day, and the control group ate energy-matched (same number of calories as the almond groups) muffins.

The trial lasted four weeks.

Before the trial, and at its completion, gut microbiota composition and diversity was analysed with 16S rRNA gene sequencing, and short-chain fatty acids were measured with gas-chromatography.

Gut transit time (the time for food to travel from the mouth and the subsequent waste to make its exit) was measured with a wireless capsule.

Stool output and gut symptoms were recorded in a diary.

Higher levels of butyrate

Researchers found that the short-chain fatty acid butyrate was significantly higher among almond eaters compared to those who consumed the muffin.

Why is this helpful?

Butyrate is the main source of fuel for the cells lining the colon.

When these cells function effectively, three good things happen:

• Gut microbes flourish
• The gut wall is strengthened against leaks and inflammation
• Nutrients are more effectively absorbed.

Can’t poo-poo these results

There was no significant difference observed in gut transit time – the time it takes for food to move all the way through the gut – between almond eaters and the muffin control group.

However, the whole-almond eaters had an additional 1.5 bowel movements per week compared to the other groups.

These findings suggest eating almonds could also benefit those with constipation.

Overall, eating whole and ground almonds was shown to improve participants’ diets, with higher intakes of monosaturated fatty acids, fibre, potassium and other important nutrients compared to the control group.