Systemic oxidative stress is associated with many disease states including diabetes, obesity, cardiovascular disease and cancer. Oxidative stress can promote inflammation, damage DNA and proteins, as well as detrimentally alter the metabolic milieu. Dietary antioxidants have been shown to be effective at combating systemic oxidative stress. In particular, plants are a rich source of many reducing compounds capable to acting as free radicals scavengers in vivo. Tea, fruit, nuts and wine have all shown beneficial effects against oxidative stress and associated inflammation, and epidemiology shows associations between intakes of these foods and a reduced risk of disease. Spices possess some of the highest per gram oxygen radical scavenging capacity (ORAC) on account of their high concentrations of phenolic compounds, which suggests that they might be useful supplements to the diet in those at risk of high levels of oxidative stress.
Because of their potent in vitro antioxidant effects and their potential to benefit oxidative stress in vivo, researchers1 have investigated the effects of adding 14g of a high antioxidant spice blend to a meal. The spice blend contained black pepper, cinnamon, cloves, garlic powder, ginger, oregano, paprika, rosemary and turmeric, and was added to a 1200kcal (5060kJ) meal comprising of a chicken curry, Italian herb bread and cinnamon biscuit. A similar control meal consisting of a coconut curry, rice dish, cheese bread and desert biscuit with no added spices was used as the control meal. The ferric reducing antioxidant power (FRAP) of plasma was two fold higher following the high antioxidant meal, suggesting that the spices had increase antioxidant status of the subjects. In addition the hydrophilic ORAC capacity of plasma was also increased with the high antioxidant meal, but not with the low antioxidant meal.
Interestingly, the high spice meal significantly decreased postprandial insulin (21% reduction in area under the curve) and triglyceride (31% reduction in area under the curve) responses to the meal, but there were no effects on plasma glucose. The reduction in triglyceride concentrations supports research on tea, and the mechanisms of this effect may be reduced gastric emptying or a direct inhibitory effect on pancreatic lipases. The reduced insulin secretion may be due to the inclusion of cinnamon, which has been shown to have insulin modulating effects. Some evidence also suggests that polyphenols enhance insulin receptor sensitivity. The authors estimated that the spices used in the meal provided an acute dose of 554 gallic acid equivalents, which would equate to ≈150mL red wine, ≈240mL blueberry juice or 40g dark chocolate. The small sample size (n=6) in this study should however, be taken into consideration when analysing this data.
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