Regular consumption of walnuts may be beneficial for digestive health by increasing the amount of good probiotic-type bacteria in the gut, according to a new study in rats from Louisiana State University and published in the Journal of Nutritional Biochemistry.
A diet with walnuts leads to an overall significant increase in the diversity of bacteria in the gut. Image credit: Utroja0.
“Gut health is an emerging research area, but we are seeing that greater bacterial diversity may be associated with better health outcomes, whereas low diversity has been linked to conditions such as obesity and inflammatory bowel disease,” said study lead author Dr. Lauri Byerley, an associate professor of research in the Physiology Department at Louisiana State University.
In the study, rats were randomly assigned to a diet containing ground walnuts, equivalent to about 2 ounces (1/2 cup) per day in humans, or a diet without walnuts for up to 10 weeks. Calorie and nutrient intake was similar between the two diet groups.
Compared to those that did not consume walnuts, rats that ate a walnut-enriched diet saw an increase in beneficial bacteria including, Lactobacillus, Roseburia, and Ruminococcaceae.
“The diet groups had distinct microbial communities with animals consuming walnuts displaying significantly greater species diversity,” Dr. Byerley and co-authors said.
“Walnuts increased the abundance of Firmicutes and reduced the abundance of Bacteriodetes.”
“They enriched the microbiota for probiotic-type bacteria including Lactobacillus, Ruminococcaceae, and Roseburia while significantly reducing Bacteroides and Anaerotruncus. The class Alphaproteobacteria was also reduced.”
“Walnut consumption altered the gut microbial community suggesting a new mechanism by which walnuts may confer their beneficial health effects.”
According to the authors, the bioactive components of walnuts may be contributing factors in providing these health benefits.
“Walnuts are the only nut that contain a significant amount of alpha-linolenic acid, the plant-based omega-3 fatty acid (2.5 grams per one ounce) and also offer protein (4 grams per one ounce) and fiber (2 grams per one ounce),” they said.
“Animal research is provided as background and used to inform future studies needed to understand the effect on humans.”
“Our results shed light on a new way that walnuts may be beneficial for health, but more research is needed to understand how these outcomes translate to humans.”
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Lauri O.Byerley et al. Changes in the Gut Microbial Communities Following Addition of Walnuts to the Diet. Journal of Nutritional Biochemistry, published online July 9, 2017; doi: 10.1016/j.jnutbio.2017.07.001
