Walnuts Improve Gut Flora: New Research

Walnuts Improve Gut Flora: New Research

Image by Clean Supper Club

Walnuts Improve Gut Flora: New Research

By Florencia Tagliavini, Nutritionist

With so many people writing about health and nutrition these days – it’s hard to know what information is trustworthy.

There has been a lot of information about nuts and their health benefits. How true is it? Well, it’s important to see if these claims are evidence based or just people & companies promoting them for diverse reasons.

There has been a lot of investigation about nuts and seeds and their potential uses and benefits over the years. Some are researched more than others but there is definitely solid evidence and studies continue to be done to understand the mechanisms and physiology of their effects on health.

A new study (May 2018) was done toΒ assess the impact of walnut consumption on the human gastrointestinal microbiota and metabolic markers of health.

What is the microbiota and why is it important?

You’ve probably heard about the good and bad bacteria living in our intestinal tract. Well, this refers to our gut flora or gut microbiota which contains tens of trillions of microorganisms, including at least 1000 different species of known bacteria with more than 3 million genes (150 times more than human genes). These microorganisms are an important part of our health with many physiological functions that experts nowadays, consider it as an “organ”. However, it is an “acquired” organ as babies are born sterile; that is, intestine colonization starts right after birth and evolves as we grow. The type of colonization or species composition is highly personalized and largely determined by our environment and our diet.

Although it can adapt to change, a loss of balance in gut microbiota may arise in some specific situations. This is called dysbiosis which may be linked to health problems such as functional bowel disorders, inflammatory bowel disease, allergies, obesity and diabetes.

So, what were the results of this new research linking walnuts to a change in our gut flora?

“Walnut consumption affected the composition and function of the human gastrointestinal microbiota, increasing the relative abundances of Firmicutes species in butyrate-producing Clostridium clusters XIVa and IV, including Faecalibacterium and Roseburia, and reducing microbially derived, proinflammatory secondary bile acids and LDL cholesterol. These results suggest that the gastrointestinal microbiota may contribute to the underlying mechanisms of the beneficial health effects of walnut consumption”.

Simply put – More good bacteria that promotes health and lowers LDL (bad cholesterol) – Another reason to love walnuts!



Holscher HD, Guetterman HM, Swanson KS, et al. “Walnut Consumption Alters the Gastrointestinal Microbiota, Microbially Derived Secondary Bile Acids, and Health Markers in Healthy Adults: A Randomized Controlled Trial”. The Journal of Nutrition, 2018; 148:861–867.

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