Bioavailability and potential anti-oxidative and anti-inflammatory effects of purple wheat functional foods
Purple wheat is a colored grain containing high levels of polyphenols which may contribute significantly to human health due to their anti-inflammatory and anti-oxidative stress effects. In this work, several prototype products from purple wheat were developed and analyzed. The physiological impact of bran-enriched whole wheat bars and crackers which had the highest level of anthocyanins and antioxidants capacity among six prototypes were investigated in two human studies involving short- and long-term consumption. The first study was a randomized, semi-blind crossover study designed to examine the bioavailability of anthocyanins and phenolic acids from purple wheat bars and crackers and their acute effects on plasma antioxidant activity and selected inflammatory biomarkers. Sixteen healthy male and female participants consumed 4 servings of the product containing 6.7 mg anthocyanins and 176-213 mg phenolic acids. Overall, acute consumption of purple wheat products was associated with rapid absorption and excretion of anthocyanin and phenolic acids metabolites, with no impact on short term plasma antioxidant activity or markers of inflammation in healthy adults. To better understand the physiological effect of purple wheat-based foods and their cumulative impacts on health, a long-term randomized, single-blind, parallel arm, intervention study was undertaken. This study assessed changes in plasma metabolic markers in overweight and obese adults (BMI ≥ 25.0 kg/m2) with underlying chronic inflammation (hs-CRP > 1.0 mg/L) when consuming 4 servings of whole purple versus regular wheat convenience bars, daily for 8 weeks. Ferulic and hippuric acids were the major metabolites in plasma, while no intact anthocyanins were detected. Consumption of purple wheat bars significantly reduced plasma IL6 and increased adiponectin and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity. Comparing between the groups, TNF-α was reduced in both groups, while glucose was significantly lowered in purple wheat group. Overall, consumption of whole purple and regular wheat bars for 8 weeks showed potential to impact markers of oxidative stress and inflammation. This thesis is the first to report on the absorption and metabolic effect of anthocyanins and phenolic acids from purple wheat products in humans. The results can support future development of purple wheat functional food products.