RCT: Blueberries may alleviate symptoms of gastrointestinal disorder
Furthermore, the report notes that pain scores improved in the blueberry treatment group, as well as scores assessing quality of life. Yet, these did not reach statistical significance.
The ‘nutrients’ published study, funded by the US Highbush Blueberry Council, concludes: “General well-being, quality of life, and life functioning, as well as abdominal symptom relief were improved significantly by blueberry ingestion compared to placebo in patients with FGID,”
“The polyphenol and fibre components of blueberries appear to exert broad beneficial effects separate from any sugar effects implicit to both treatments,” the researchers emphasise with regards to the significance of the findings.
Polyphenols are phytochemicals prevalent in a vast array of plants, which have been found to exhibit a range of health benefits whilst providing an important source of antioxidants in our diet. Blueberries are among the most studied sources of polyphenols, with studies noting their abilities to reduce cardiovascular disease risk, type 2 diabetes, and improve cognition.
Despite blueberries exhibiting antioxidant, anti-inflammatory and membrane permeability reversing properties, there has been limited research into their potential benefits for FGIDs. Such conditions, including irritable bowel syndrome (IBS) and functional dyspepsia (FD), have a significant prevalence of 10-15% in many populations. The disorders are characterised by modulated microbiome composition, gut permeability, and immune activation, all of which are known to be influenced by diet.
Thus, there is strong potential for polyphenol-rich blueberries to exhibit beneficial effects to those suffering with FGIDs, prompting the researchers to conduct the present randomised control trial to understand the effects of consumption on associated symptoms.
The researchers recruited 43 patients, aged 18-60 years, suffering with FGID. Subjects were randomised into equal groups of ten to be administered either 30g freeze-dried blueberries (equivalent to 180g fresh blueberries) or the placebo, in balanced blocks. The treatment periods lasted six weeks, with a washout period of two to four weeks before being crossed over into the alternative treatment group.
Subsequent Gastrointestinal Clinical Rating Scale (GSRS) scores and measures of abdominal symptom relief were collected from the participants and compared as primary outcome measures. Further quality of life ratings, Bristol stool scales, and fructose breath test results were collated as secondary outcomes measures, to understand the role of the enteric microbiome metabolism.
It was observed that the blueberry treatment resulted in significantly more patients reporting symptom relief, when compared to the placebo (53% vs. 30%).
Both pain and abdominal signs and symptoms overall were found to improve, yet these measures did not reach statistical significance. Quality of life and life functioning scores were also noted to improve following blueberry treatment, when compared to the placebo.
The significance evidence collated by the study suggests that the polyphenol-rich blueberries were able to relieve abdominal symptoms, whilst also improving general markers of well-being and quality of life measures. This has opened this area of potential research to further investigate their efficacy within dietary interventions for FGD treatment.
With regards to the mechanism of action, the report explains: “Blueberries can via its polyphenol and sugar components modulate several mechanisms implicated in the pathogenesis of FGID, including inflammation, neural sensitization, intestinal permeability, and the composition and metabolism of the enteric microbiota.”
Yet the researchers emphasise: “In future studies a detailed separation of the polyphenol, fibre, and sugar effects on the mechanisms implicated in FGID would be helpful to provide clinical treatment guidelines.”
“Blueberries Improve Abdominal Symptoms, Well-Being and Functioning in Patients with Functional Gastrointestinal Disorders”
by Clive H. Wilder-Smith, Andrea Materna and Søren S. Olesen