Researchers at the University of Connecticut Health (UConn Health) and Texas A&M University demonstrated that walnut supplementation in mice with ulcerative colitis -- a chronic inflammatory bowel disease -- helped protect their colons from damage.
The study, led by Daniel Rosenberg and Masako Nakanishi from the Center for Molecular Oncology at UConn Health, explored the protective effects of walnut supplementation on intestinal inflammation during both the acute and recovery phase of ulcerative colitis.
Walnuts may protect against ulcerative colitis
Ulcerative colitis is a chronic inflammatory condition that affects the colon and is marked by alternating periods of clinical remission and disease flare-ups. Current studies suggest that certain foods can trigger or suppress these flare-ups.
For this reason, ulcerative colitis patients are often placed on restricted diets, which contain foods that can reduce inflammation and suppress flare-ups. These include nuts, fruits, vegetables and other plant-based foods.
Walnuts, in particular, are the richest source of omega-3 fatty acids, a group of polyunsaturated fatty acids hailed for their anti-inflammatory properties. (Related: Consuming EPA and DHA omega-3 produces a “desirable” Omega-3 Index score and also reduces your risk of heart disease.)
To assess the reported anti-inflammatory properties of these nuts, the researchers fed mice a diet containing freshly ground walnuts after chemically inducing ulcerative colitis.
After two weeks of walnut supplementation, they found that the colons of mice that received walnuts sustained less injury after an episode of ulcerative colitis. The linings of the mice's colons (colonic mucosa) also started to exhibit signs of repair and healing.
In addition, the researchers noted that these effects were more apparent in mice that were fed large amounts of walnuts. In particular, mice that received the largest amount (14 percent of their diet) had significant reductions in the total ulcerated areas of their colons following walnut supplementation.
Taken together, these findings offer experimental evidence that walnuts can protect the colon from damage caused by chronic inflammatory diseases.
Walnuts can alter the colonic environment
The researchers also postulated that this protection may be attributed to the metabolites that form inside the colon following walnut supplementation. These metabolites appear to alter the colonic environment and “pre-condition” the colonic mucosa to either resist the initial ulcer-inducing damage or facilitate repair of the damage.
In a separate experiment, the team identified metabolites present in fecal samples from the mice taken before and after they were fed a diet containing 14 percent walnuts for two weeks.
Their analysis confirmed that walnut supplementation increased the amount of omega-6 and omega-3 fatty acids, including docosahexaenoic acid (DHA). DHA supplementation is known to protect against inflammation caused by oral and gastrointestinal diseases.
The team also found elevated amounts of other metabolites, such as linoleic acid metabolites and tryptophan metabolites, in the fecal samples taken after walnut supplementation. Linoleic acid and tryptophan are amino acids that play a key role in modulating the gut microbiome, which is important for the maintenance of good gut health.
These additional findings, the researchers believe, may be the key to identifying the molecular mechanisms behind the protective effects of walnuts against ulcerative colitis and other gastrointestinal conditions.
Rosenberg noted, however, that further research is needed to identify the exact compounds responsible for these protective effects, and to determine if the metabolic changes that occur in the colon after walnut consumption are part of these effects.
Read more articles about the health benefits of walnuts and other plant-based foods at FoodIsMedicine.com.
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