Reference Number: 65
Epidemiology associates whole-grain (WG) consumption with several health benefits. Mounting evidence suggests that WG wheat polyphenols such as Ferulic acid play a role in mechanisms underlying health benefits.
The objective was to assess circulating concentration, excretion, and the physiologic role of WG wheat polyphenols in subjects with suboptimal dietary and lifestyle behaviors.
A placebo-controlled, parallel-group randomized trial with 80 healthy overweight/obese subjects with low intake of fruits and vegetables and sedentary lifestyle was performed. Participants replaced precise portions of refined wheat (RW) with a fixed amount of selected WG wheat or RW products for 8 wk. At baseline and every 4 wk, blood, urine, feces, and anthropometric and body composition measures were collected. Profiles of phenolic acids in biological samples, plasma markers of metabolic disease and inflammation, and fecal microbiota composition were assessed.
WG consumption for 4–8 wk determined a 4-fold increase of serum dihydroferulic acid (DHFA) and a 2-fold increase of fecal ferulic acid (FA) compared with RW consumption (no changes). Similarly, urinary FA at 8 wk doubled the baseline concentration only in WG subjects. Concomitant reduction of plasma tumor necrosis factor-? (TNF-?) after 8 wk and increased interleukin (IL)-10 only after 4 wk with WG compared with RW (P = 0.04) were observed. No significant change in plasma metabolic disease markers over the study period was observed, but a trend toward lower plasma plasminogen activator inhibitor 1 with higher excretion of FA and DHFA in the WG group was found. Fecal FA was associated with baseline low Bifidobacteriales and Bacteroidetes abundances, whereas after WG consumption, it correlated with increased Bacteroidetes and Firmicutes but reduced Clostridium. TNF-? reduction correlated with increased Bacteroides and Lactobacillus. No effect of dietary interventions on anthropometry and body composition was found.
SIGNIFICANCE OF THIS STUDY
The current study found that whole grain wheat consumption significantly increased excreted ferric acid and dihydroferulic acid. The study demonstrated for the first time that wholegrain wheat FA is released and absorbed in the gut and is likely metabolized by gut microbiota, and DHFA is the most abundant circulating metabolite in overweight/obese subjects. The study showed an increase in specific healthy gut microbes such as Firmicutes and Bacteroidetes following WG consumption. The increased abundance of these bacteria together with Lactobacillus was associated with the decreased inflammatory status of subjects receiving WG treatment, which may suggest that WG FA may play a role in reducing the risks associated with asymtomatic inflammation.