Whole Grain Polyphenol Bioavailability and Effects on Health
Condition: Overweight
MeSH terms: Overweight
Study type: Interventional

Summary: 
      Whole grains (WG) contain numerous physiologically bioactive compounds, a key group being
      polyphenolic compounds such as ferulic acid (FA). These whole grain polyphenolic compounds
      have been shown to have potent antioxidant activity. This study will evaluate bioavailability
      of WG bioactive compounds and their physiological impact on health outcomes, mainly related
      to inflammatory, oxidative and hormonal status, in overweight subjects.
    

Detailed description: 
      Epidemiological evidence indicates that consumption of whole grains (WG) is associated with
      improved health and decreased risk for common chronic diseases. However there is paucity of
      intervention data regarding the beneficial effects of WG in vascular health and associated
      metabolic disorders.

      From 2007 up to now five main intervention studies using WG were published. The results from
      these studies consistently showed no efficacy of WG to modify biochemical parameters in
      free-living subjects including WG in their habitual diet. Anyway some drawbacks could be
      found and mainly regarding subject compliance to the treatment and the type of WG-rich foods
      supplied.

      Our working hypothesis is based on WG physiologically bioactive compounds mainly polyphenolic
      compounds such as ferulic acid (FA). FA is covalently bound to arabinoxylans constituting WG
      dietary fiber. This structure represents a natural way to carry polyphenol compounds, into
      the lower gut. A previous work indicated that intestinal microflora particularly
      Bifidobacteria and Lactobacilli is able to ferment WG polysaccharide moiety (prebiotic
      effect) and at the same time microbial esterases can release free phenolic acids. The free
      acids are adsorbed through the colon barrier into the blood. The slow and continuous release
      of phenolic acids, particularly FA, determines an increase of baseline level of FA in the
      blood of WG consumers. However no study correlated FA plasma concentration with health
      parameters such as biomarkers of inflammation, glucose metabolism and oxidative status which
      may be in turn associated to the CVD risk.

      In this framework a controlled, parallel, two arm intervention study will be performed using
      a WG-rich product that will be selected from those commercially available for having a high
      content of FA (>500 mg/kg). The aim of this study is to evaluate the bioavailability of FA
      over a two month-treatment in overweight subjects and to correlate variation of FA plasma
      concentrations with biomarkers of oxidative (plasma antioxidant capacity, MDA) and
      inflammatory (CRP, anti- and pro-inflammatory cytokines) status, with nutritional status and
      with gastro-intestinal hormones related to appetite and glucose metabolism (ghrelin, PYY, PP,
      insulin, GLP-1, GIP and leptin). Eighty subjects will be selected in the respect of strict
      inclusion and exclusion criteria and will be randomized to include WG in opportunely revised
      individual habitual diet, or to continue with their habitual diet. At baseline, after 1 month
      and after 2 months from starting the protocol, blood drawings will be performed and urine and
      feces will be collected from fasting subjects. Gastro-intestinal hormone response and glucose
      metabolism following a standard meal will be also evaluated at baseline and at 2 months.
    

Intervention name(s): Whole grains
Intervention type(s): Dietary Supplement
Intervention description(s): Subjects will consume whole grains at dose of 80 g/die, for two months
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: whole grains; polyphenols; overweight; bioavailability; antioxidant status; inflammation