Healthy and diverse dietary patterns, including those that incorporate nuts, benefit gut health.

The gut microbiota (the community of different bacteria in the intestine) is an increasingly popular area of study among researchers. Gut health is now believed to impact on the development of many chronic diseases, such as obesity.

Estimates suggest that around 100 trillion micro-organisms colonise the gut. And the type and amount of these micro-organisms can vary, depending on a number of factors. Age, gender, genetics, weight, health status, diet and medications, such as antibiotic use, impact the make-up of our gut microbiota. Whilst evidence is emerging, there is still much that we have yet to understand about the microbiome. 

Many foods impact on the amount and diversity of bacteria, one of which is nuts [1].

What role do nuts play in gut health?

Preliminary research suggests nuts could be good for gut health. Nuts, and more specifically nut skins, are high in fibre and polyphenols, which provide antioxidant and anti-inflammatory properties. This emerging research adds to the large body of established evidence on how nuts improve health and wellbeing.

Nuts act as ‘food’ for the gut bacteria

Nuts are foods (prebiotics) for the bacteria (probiotics) and nut skins in particular, appear to play an important role since they are rich in fibre and polyphenols, with antioxidant and anti-inflammatory properties [2]. Studies conducted with almonds [3] and pistachios [4] have reported increases in the growth of beneficial bacteria leading to increased butyrate – a short chain fatty acid (SCFA)  – which is thought to keep colon cells healthy. 

Did you know? A handful (30g) of mixed tree nuts provides 2.1g fibre (around 7.1g/100g). Among tree nuts, chestnuts (14.9g/100g), almonds (10.9g/100g) and hazelnuts (10.4g/100g) contain the most dietary fibre.

Nuts may offer protection to probiotic bacteria

A study conducted by Blaiotta et al [5] found chestnut extract and chestnut flour help different strains of lactobacilli bacteria to survive stomach acids and bile. This means they are more likely to make it to the large intestine intact where they do their good work.

Nuts and weight

Research has shown that people who regularly consume nuts are less likely to be overweight or obese [6]. We don’t have all the answers yet as to why this is the case. But 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 bacteria, they may play a role. 

Short chain fatty acids are produced when healthy bacteria feed on fibre, and these compounds may play a role in weight management by influencing hormones in the gut that make us feel full, and making the body more sensitive to insulin [7-9].

Research also shows that people with greater diversity of intestinal bacteria and higher levels of specific bacterial strains (such as faecalibacterium, bifidobacterium and lactobacillus) are less likely to be overweight, have less insulin resistance, and lower blood cholesterol and inflammation [7,10,11].

The bottom line

Research to date tells us that healthy dietary patterns, including those that incorporate nuts, provide prebiotics and probiotics – which in turn, positively affect the gut microbiome. The area of gut health offers promising results – and there’s still so much left to learn!