Walnuts May Impact Gut Microbiome and Improve Health
New Delhi, 8th May 2018: According to a study conducted by the University of Illinois, walnuts impact the gut microbiome – the collection of trillions of microbes or bacteria in the gastrointestinal tract – in a way that may be behind some of health benefits.
Findings from the study show that consuming walnuts not only impacted the gut microbiota and microbial-derived secondary bile acids, but also reduced LDL-cholesterol levels in the adults participating in the study; good news for cardio, metabolic, and gastrointestinal health.
Diets rich in nuts, such as walnuts, have been shown to play an important role in heart health and in reducing colorectal cancer. Dietary fiber acts as a food source for gut microbiota, helping the bacteria to do their jobs – breaking down complex foods, providing us nutrients, or helping us feel full.
Hannah Holscher, Assistant Professor of food science and human nutrition at University of Illinois said, “We found that when you consume walnuts it increases microbes that produce butyrate, a beneficial metabolite for colonic health. So the interaction of walnuts with the microbiome is helping to produce some of those health effects.”
For the controlled-feeding study, 18 healthy male and female adults consumed diets that either included 0 grams of walnuts or 42 grams – about a third cup or a palm-full of walnuts – for two, three-week periods. Fecal and blood samples were collected at the beginning and end of each period to assess secondary outcomes of the study, including effects of walnut consumption on fecal microbiota and bile acids and metabolic markers of health. Walnut consumption resulted in a higher relative abundance of three bacteria of interest: Faecalibacterium, Roseburia, and Clostridium.
“The microbes that increased in relative abundance in this walnut study are from one of the Clostridium clusters of microbes, and there’s increased interest in those because they have the ability to make butyrate,” Holscher said. “Unfortunately in this study we didn’t measure butyrate, so we can’t say that just because these microbes increased that butyrate did increase. We still need to answer that question.”
“There is a lot of interest in Faecalibacterium because it has also been shown in animals to reduce inflammation. Animals with higher amounts also have better insulin sensitivity. There is also growing interest in Faecalibacterium as potential probiotic bacteria, and so we are trying to follow up on foods that help support Faecalibacterium.”
The findings also showed that with walnut consumption, a reduction in secondary bile acids compared to the control.
“Secondary bile acids have been shown to be higher in individuals with higher rates of colorectal cancer,” Holscher explained. “Secondary bile acids can be damaging to cells within the GI tract, and microbes make those secondary bile acids. If we can reduce secondary bile acids in the gut, it may also help with human health.”
Previous research that prompted this microbial research showed that the amount of energy (calories) derived from walnuts after we eat them is less than previously thought.
Walnuts are just one in-a-line food that contain dietary fiber and have interested scientists for their impact on the microbiome and health. Fruits, vegetables, whole grains, nuts, and legumes are important plant sources of dietary fiber. Eating a variety of these foods helps promote a diverse gut microbiota, which in turn helps to support health.
About California Walnut Commission
The California Walnut Commission (CWC) is funded by mandatory assessments of the growers. The CWC is an agency of the State of California that works in concurrence with the Secretary of the California Department of Food and Agriculture (CDFA). The CWC was established in 1987 under California law. This allows the industry to organize and assess itself (in this case the growers) in order to generate monies to accomplish a myriad of activities. The CWC’s primary interest, however, is and has been since its inception, export market development.
Today they also conduct extensive health and nutrition research and take an active role in publicizing the outcomes in all markets including the United States. An important facet of their operation involves the evaluation of its marketing efforts through market research and are also responsible for communication within the industry with more than 4,800 growers in the state of California.