Diabetes and obesity have sparked interest in identifying healthy, dietary carbohydrates as functional ingredients for controlling blood glucose and insulin levels. Grain sorghum has been known to be a slowly digestible cereal; however, research is limited on its health effects in humans. The objectives of this study were to measure the contents of functional starch fractions, SDS (slowly-digestible starch) and RS (resistant starch), and to investigate the effects of grain sorghum on postprandial plasma glucose and insulin levels in 10 healthy men. A whole-wheat flour muffin (control) was compared with the grain sorghum muffin with both muffins containing 50 g of total starch. Using a randomized-crossover design, male subjects consumed treatments within a one-week washout period, and glucose and insulin levels were observed at 15 minutes before and 0, 15, 30, 45, 60, 75, 90, 120, 180 minutes after consumption. The mean glucose responses reduced after consuming grain sorghum, particularly at 45–120 minute intervals, and mean insulin responses reduced at 15–90 minute intervals compared to control (P < 0.05). The mean incremental area under the curve (iAUC) was significantly lowered for plasma glucose responses about an average of 35% from 3863 ± 443 to 2871 ± 163 mg (∼3 h) dL⁻¹ (P < 0.05). Insulin responses also reduced significantly from 3029 ± 965 μU (∼3 h) L⁻¹ for wheat to 1357 ± 204 with sorghum (P < 0.05). Results suggest that grain sorghum is a good functional ingredient to assist in managing glucose and insulin levels in healthy individuals.

Red clover (Trifolium pratense) possesses various dietary compounds that improve human health. However, the functions of anthocyanins in red clover remain unclear. Here we examined anti-inflammatory and antioxidant effects of red clover extract (RC) and red clover anthocyanins fraction (RCA) using lipopolysaccharide (LPS)-treated RAW 264.7 macrophages and identified dietary compounds. RC and RCA suppressed LPS-induced expression of genes such as tumor necrosis factor (TNF)α, interleukin (IL)1β, inducible nitric oxide synthase (iNOS), monocyte chemoattractant protein (MCP)1, and cyclooxygenase (COX)2. LPS-stimulated intracellular reactive oxygen species (ROS) production also was prevented by both RC and RCA. NADPH oxidase 1 (NOX1) gene and phosphorylation of p47^phox of NOX1 that were increased by LPS were inhibited in the cells treated with RCA. LPS-stimulated nuclear factor erythroid 2-related factor 2 (NRF2) gene expression and nuclear translocation of nuclear factor kappa B (NF-kB) subunit p65 were suppressed together with reduced iNOS and COX2 proteins by RCA. Additionally, 27 polyphenols and 7 anthocyanins from RC were identified and quantified. In conclusion, RC, especially RCA, exerted anti-inflammatory and anti-oxidative activities in vitro by regulating NF-κB and NRF2 signaling pathways, suggesting that anthocyanins in red clover are the potential candidates to reduce inflammation and oxidative stress.

The human gut microbiota is considered as a crucial mediator between diet and gut homeostasis and body weight. The unique polyphenolic profile of sorghum bran may promote gastrointestinal health by modulating the microbiota. This study evaluated gut microbiota and modulation of short-chain fatty acids (SCFA) by sorghum bran polyphenols in in vitro batch fermentation derived from normal weight (NW, n = 11) and overweight/obese (OO, n = 11) subjects’ fecal samples. Six separate treatments were applied on each batch fermentation: negative control (NC), fructooligosaccharides (FOS), black sorghum bran extract (BSE), sumac sorghum bran extract (SSE), FOS + BSE, or FOS + SSE; and samples were collected before and after 24 h. No significant differences in total and individual SCFA production were observed between NW and OO subjects. Differential responses to treatment according to weight class were observed in both phyla and genera. Sorghum bran polyphenols worked with FOS to enhance Bifidobacterium and Lactobacillus, and independently stimulated Roseburia and Prevotella (p < 0.05). Our results indicate that sorghum bran polyphenols have differential effects on gut health and may positively impact gut ecology, with responses varying depending on weight class.

Whole grain rice is a rich source of fiber, nutrients, and phytochemicals that may promote gastrointestinal health, but such beneficial components are typically removed with the bran during polishing. Soluble feruloylated arabinoxylan oligosaccharides (FAXO) and polyphenols (RBPP) isolated from rice bran are hypothesized to have positive impacts on human gut microbiota through a prebiotic function. Using an in vitro human fecal fermentation bioassay, FAXO and RBPP treatments were assessed for short-chain fatty acids (SCFA) production patterns and by evaluating their impacts on the phylogentic composition of human gut microbiota by 16S rRNA gene sequencing. Fresh fecal samples collected from healthy adults (n = 10, 5 males, 5 females) were diluted with anaerobic medium. Each sample received five treatments: CTRL (no substrates), FOS (fructooligosaccharides), FAXO, RBPP, and MIX (FAXO with RBPP). Samples were incubated at 37 °C and an aliquot was withdrawn at 0, 4, 8, 12, and 24 h Results showed that SCFA production was significantly increased with FAXO and was comparable to fermentation with FOS, a well-established prebiotic. RBPP did not increase SCFA productions, and no significant differences in total SCFA production were observed between FAXO and MIX, indicating that RBPP does not modify FAXO fermentation. Changes in microbiota population were found in FAXO treatment, especially in Bacteroides, Prevotella, and Dorea populations, indicating that FAXO might modulate microbiota profiles. RBPP and MIX increased Faecalibacterium, specifically F. prausnitzii. Combined FAXO and RBPP fermentation increased abundance of butyrogenic bacteria, Coprococcus and Roseburia, suggesting some interactive activity. Results from this study support the potential for FAXO and RBPP from rice bran to promote colon health through a prebiotic function.