Walnuts are known to boost the health of the heart. Not only this, they also reduce the chances of having colorectal cancer as revealed by a study that they impact the gut microbiome – a term, which represents a group of zillions of bacteria in the gastrointestinal tract.
Walnuts have dietary fiber. Scientists are interested in understanding their effect on the overall heath and particularly, microbiome. Researchers say that dietary fiber is a source of food for the gut microbiota. It helps the bacteria in breaking down complex foods and give us nutrition and making us feel satiated.
Researchers added that diets high on nuts like walnuts help protect the heart and also reduce colorectal cancer.
This study was published in The Journal of Nutrition. It showed that eating walnuts not only impacts the microbiota and secondary bile acid derived from microbes, but it also reduces the level of low-density lipoprotein (LDL) or ‘bad cholesterol.’ It is therefore beneficial for metabolic, gastrointestinal and cardiovascular health.
Hannah Holscher, assistant professor at the University of Illinois, said that when walnuts are consumed, there is a resultant rise in microbes that make butyrate, which is good for the health of the colon. So, health benefits can be seen when walnuts interact with the microbiome.
Holscher added that it is about understanding how microbes are interfere with the foods that we eat and subsequent beneficial health effects.
In the study, 18 healthy females and males (adults) were examined. Out of these participants, some did not consume walnuts, while the rest had 42 gram – one third of a cup or a palm full – of walnuts for a period of 2-3 weeks.
Blood and fecal samples were collected at the start and end of the study to assess the effects of the consumption of walnuts on bile acids and fecal microbiota. The result indicated that the consumption of walnuts led to increase in relative abundance of several types of bacteria, including Roseburia, Faecalibacterium, and Clostridium.
The increase in microbes are from one of the Clostridium genus of the bacteria and these are scientifically intriguing since they are capable of producing butyrate.
In this study, butyrate was not measured, so it cannot be said that butyrate increased just because there was an increase in the number of microbes. So, this question remains unanswered for now.