In the news: New Findings for Flavonoid-Rich Blueberries: Gut & Bone Health

Blueberries May Play a Role in GI Health

Blueberries are a great source of fiber and polyphenols (e.g., flavonoids like anthocyanins) best known for their ability to reduce the risk type 2 diabetes, heart disease and mental decline associated with aging.

Aside from these benefits, a new study(1) conducted by a Swiss and Danish research team suggests that these berries can help with symptoms of functional gastro-intestinal disorders (FGIDs) too. FGIDs are also known as disorders of the gut-brain interaction. The gut-brain axis links emotional and thinking centers of the brain with intestinal function.

FGIDs include conditions such as irritable bowel syndrome and functional dyspepsia characterized by symptoms of upper GI pain and/or a feeling of indigestion or mild discomfort with fullness after eating.

In the study, 43 participants with FGID consumed 30 grams of freeze-dried blueberries (equivalent to 180 grams or a little more than a cup of fresh blueberries) or a sugar and calorie-matched placebo for a 6-week period. Then, after a washout period of several weeks, the participants crossed over to the alternate treatment for another 6 weeks.

The blueberry treatment resulted in more patients reporting abdominal symptom relief compared to placebo (53% vs. 30%,). General markers of well-being and quality of life measures improved with blueberry consumption more than with placebo. Clinical scores also improved, though the improvements didn’t achieve statistical significance.

The researchers suggest that blueberries may be beneficially influencing inflammation, nerve sensitivity, and the permeability of the intestinal wall in helping with symptom relief. Additionally, the berries may be positively affecting the composition and metabolism of gut microflora. GI tract bacteria have an important role in bi-directional interactions between the gut and the brain.

Could Blueberries Bolster Bone Health?

It’s too soon to answer that question, but the results of preclinical studies suggest that blueberries are associated with improved bone health. Also, dietary flavonoid intake has been linked with better bone mineral density in population-health studies.

In a small, new study(2), researchers examined the effects of blueberry consumption on changes in bone balance. Bone is constantly broken down and rebuilt. During menopause there is a decrease in bone formation and an accelerated rate of bone breakdown caused by hormonal changes.

The investigators looked at bone calcium retention with blueberry treatment vs. no treatment in post-menopausal women. Participants were assigned to a random sequence of three 6-week interventions: a low (17.5 g/d), medium (35 g/d), or high (70 g/d) dose of freeze-dried blueberry powder equivalent to 3/4, 1½, or 3 cups daily of fresh blueberries.

Consuming the low and medium amounts of blueberries resulted in better bone calcium retention, while the high dose did not result in better bone calcium balance. The two lower doses also reduced a marker of bone breakdown.

The researchers refer to the different responses of lower vs. higher amounts of blueberries as a hormetic effect – in this case a neutral effect that has been seen in studies where blueberries were tested in animal models of menopause.

The authors suggest that eating moderate amounts of blueberries – less than a cup of the fresh berries a day – could be one strategy to help ease bone loss in healthy postmenopausal women.

References

1. Wilder-Smith CH, et al. Blueberries improve abdominal symptoms, well-being and functioning in patients with functional gastrointestinal disorders. Nutrients. 15(10), 2396, 2023.
2. Hodges JK, et al. Moderate consumption of freeze-dried blueberry powder increased net bone calcium retention compared with no treatment in healthy postmenopausal women: A randomized cross-over trial. AM J Clin Nutr. Online June 1, 2023.