Precision nutrition and the gut microbiome: the impact of blueberries

In a recent study published in the journal Antioxidants, researchers explored the impacts of precision nutrition on gut microbiome variation.

Study: Variation in crop, host and gut microbiome influences precision nutrition: an example of blueberries. Image Credit: BukhtaYurii/Shutterstock.com

Background

Nutrition research funding is increasingly focused on precision nutrition, which has recently received significant interest. Fruit and vegetable consumption is linked to a lower risk of developing chronic diseases such as obesity, cardiovascular disease, diabetes and neurocognitive diseases.

Berries, tea and cocoa contain (poly)phenolic compounds identified as potentially beneficial to health among the thousands of phytochemicals studied.

Epidemiological studies have prompted more research into the health benefits of blueberries and blueberry-rich foods. More research is needed to uncover the mechanisms of action behind these health benefits.

About the study

In the present study, the researchers showed the variety of polyphenol profiles found in blueberries, examined the bioavailability of anthocyanins in blueberries of different forms, and explored their impact on the gut microbiome.

The anthocyanin profiles of 267 blueberry genotypes were analyzed at the North Carolina State University Piedmont Research Station in Salisbury, North Carolina. Genotypes included both commercial varieties and genetic selections.

Principal component analysis (PCA) was conducted on 17 anthocyanins analyzed in each genotype using a multivariate statistical method. Blueberry genotypes with different anthocyanin profiles were chosen based on their distinct profiles by PCA.

These genotypes were then analyzed to determine their polyphenolic profiles. The bioavailability of flavonoids was further tested in ovariectomized rats, which serve as a model for postmenopausal bone loss in women.

Six genotypes were chosen for the study, including three rabbit eye genotypes (Vaccinium virgatum) including Montgomery, Ira, and Onslow, along with three southern highbush genotypes (V. corybosum) such as Sampson, Legacy and SHF2B1-21:3.

The plasma was subjected to solid phase extraction (SPE) to extract flavonols, anthocyanins and flavan-3-ol metabolites, which were subsequently analyzed.

The impact of cranberries on bone calcium retention was studied in four-month-old female ovariectomized Sprague Dawley rats through microbiome analysis. The team extracted deoxyribonucleic acid (DNA) from fecal samples and sequenced the resulting amplicons.

The study involved 20 rats and 160 fecal samples collected at various stages, including the baseline, 10-day cranberry treatments, and wash stages for microbiota analysis.

Results

Anthocyanins identified from plants belonging to the same genotype included cyanidin 3-O-galactoside, cyanidin 3-O-arabiniside, cyanidin 6-O-glucoside, cyanidin 3-O-glucoside, delphinidin 3-O-arabiniside, delphinidin 3-O – galactoside, delphinidin 6-O-glucoside, delphinidin 3-O-glucoside, malvidin 3-O-galactoside, malvidin 3-O-arabiniside, malvidin 3-O-glucoside, malvidin 6-O-galactoside, peonidin 3-O- galactoside , malvidin 6-O-glucoside, petunidin 3-O-glucoside, petunidin 6-O-glucoside and petunidin 3-O-arabiniside.

The study analyzed six blueberry genotypes and four members of the Vaccinium genus to determine their total phenolic (TP) content and monomeric anthocyanins.

The results showed that the blueberry and Lowbush Blueberry (LB) composite had higher phenolic and total monomeric anthocyanin levels than their highbush counterparts.

The total phenolic content ranged from 1,951 to 4,627 mg/100 g of berry, while the total monomeric anthocyanins ranged from 369 to 1,722 mg/100 g.

Approximately 50% of all phenolic compounds present in blueberries were anthocyanins, the most abundant phenolic class in Vaccinium species. The ten genotypes examined showed significant differences in the levels and proportions of the various anthocyanins.

The blueberry and LB composite genotypes had the highest anthocyanin levels, which is consistent with their highest levels of total phenolic and total monomeric anthocyanins.

Blueberries showed the most significant amounts of cyanidin and delphinidin species, while the LB composite showed the highest levels of malvidin and acylated anthocyanins. Cranberries had a distinct anthocyanin profile compared to other berries, exhibiting high levels of peonidin but reduced levels of malvidin, delphinidin and petunidin.

The tested genotypes showed different levels of glycosylation, with most having a significant content of arabinoside and galactoside derivatives. Specific genotypes, such as Legacy, Ira and Sampson, had remarkably low amounts of glucoside derivatives. In contrast, other genotypes, including Onslow, wild blueberry (WBB), bilberry, SHF2B1-21:3, and LB composite, showed amounts of glucoside derivatives equal to or higher than those of their arabinoside and galactoside derivatives.

Plasma samples from OVX rats showed the presence of various anthocyanin metabolites such as delphinidin-3-O-glycosides, cyanidin-3-O-glycosides, peonidin-3-O-glycosides, malvidin-3-O-glycosides and petunidin3- O -glycosides after an acute dose.

Cyanidin-3-O and malvidin-3-O-glycoside glycosides had higher bioavailability in Montgomery blueberries than in other berries.

The study found that cranberry dosage had a significant impact on the Firmicutes/Bacteroidota ratio, which decreased with increasing dosage. The ratios were highest in samples without blueberry diets and gradually decreased in samples with increasing blueberry concentrations.

Additionally, comparisons of diversity in the gut microbiome in each sample showed considerably more variety among samples with higher blueberry treatments.

In addition, the team noted that two taxa from the phylum Actinobacteria, one from the phylum Bacteroidota family Prevotellaceae_UCG-001 and one from the Firmicutes family Anaerovoracaceae XIII_UCG-001 had higher proportions after blueberry treatments.

Conclusion

The results of the study showed that the phenolic profiles of blueberries vary according to their genetic background, influencing their bioavailability and the metabolism of their polyphenols. The team also found evidence of a response in the gut microbiome to the blueberry dose.

The diversity found in culture systems, from growth to consumption to the gut microbiome, can be used to improve crop selection, rearing methods and identification of critical genotypes. This information can help understand functional health responses and develop precision nutrition practices.