Healthy dietary patterns, including those that incorporate nuts, benefit gut health. And a healthy gut, in turn, plays a crucial role in overall health.

In recent decades, research has explored the relationship between the community of microorganisms in the gastrointestinal system (the gut microbiota) and their influence on digestion, immunity and disease prevention (1).

Did you know? Estimates suggest that around 100 trillion microorganisms colonise the gut. And the make up of the gut microbiota varies, depending on many factors – such as age, gender, genetics, health status, medication use, and stress, as well as diet and other lifestyle factors, like exercise.

Although research on the gut microbiota has expanded dramatically in recent years, there is still much left to understand. What is clear is that diet is one of the most important modulators of gut microbiota composition and function (2,13).

Dietary patterns rich in prebiotics, fermented foods, and plant-based bioactive compounds, including polyphenols and flavonoids, promote microbiome diversity and stability.

What role do nuts play in gut health?

Nuts contain dietary fibres, unsaturated fatty acids, and polyphenols, which offer antioxidant and anti-inflammatory benefits – and may impact the composition of the gut microbiota and overall gut health (3,4).

Research suggests nuts have a prebiotic effect on the gut microbiota, with some of the non-digestible components of nuts (such as polyphenols and polysaccharides) acting as substrates or ‘fuel’ for beneficial bacteria in the gut (5).

Studies conducted with almonds and pistachios have reported increases in the growth of beneficial bacteria, leading to an increase in the production of the short-chain fatty acid (SCFA) butyrate, which is thought to help keep the cells in the large intestine healthy (6,7).  

Nuts may also offer protection to probiotic bacteria. A study (8) found chestnut extract and chestnut flour help different strains of lactobacilli bacteria to survive stomach acids and bile, helping these ‘good bacteria’ make it to the large intestine.

Nuts, gut health and weight

Research has shown that regular nut consumption does not lead to weight gain – and in fact, may instead support weight management (9,10).

The healthy bacteria in the body, and the compounds they generate, may be one mechanism impacting weight control. And as nuts can both feed and protect gut bacteria, this may help explain how nut consumption supports weight management.  

Some research suggests that the SCFAs produced when healthy bacteria feed on fibre, from foods like nuts, may play a role in weight management by influencing hormones in the gut that impact satiety, and by making the body more sensitive to insulin (11,12).

The food matrix of nuts might represent a unique method of delivering a rich supply of fermentable nutrients such as fibre, polyphenols and lipids to the gut microbiota (3).

Nuts, gut health and cardioprotection

Emerging research on the ‘gut-heart axis’ suggests a crucial link between the make-up of the gut microbiota and cardiovascular health.

And the gut microbiota may help explain, in part, how healthy diets, like the Mediterranean diet, lower the risk of cardiovascular disease (13).

Research suggests SCFAs, like butyrate – which are produced from the digestion of nuts and other fibre-rich plant foods, like seeds, whole grains, legumes, fruit and vegetables – could be behind some of these cardioprotective benefits.

Did you know? Studies have shown an imbalance in gut microbiota composition to be linked to a higher risk of major cardiovascular events, such as atherosclerosis, heart failure, and stroke (14).

The bottom line

Some studies have shown that nut consumption promotes a healthy gut microbiota. But research in this area is still at an early stage.

What we do know is that nuts have a unique composition and physical structure, being rich in dietary fibres, unsaturated fatty acids, and plant-based bioactive compounds, such as polyphenols – all of which are known to influence gut health.

Healthy plant-rich dietary patterns, including those that incorporate nuts – such as the Mediterranean diet, have been shown to positively impact gut health.