Spicy Food May Boost Metabolism

Aug. 12, 2011— -- Spicing up dinner may have metabolic benefits, particularly when it comes to insulin and triglyceride levels, a small study showed.

Adding a combination of various spices -- including turmeric, cinnamon, rosemary, oregano, garlic powder, and paprika -- to a plain meal significantly reduced postprandial insulin and triglyceride levels, Sheila West of Penn State University and colleagues reported online in the Journal of Nutrition.

"Antioxidants like spices may be important in reducing oxidative stress and thus reducing the risk of chronic disease," West said in a statement.

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Spices have shown antioxidant properties in vitro, and they have high antioxidant activity.

There's been much interest in the potential of dietary antioxidants to moderate oxidative stress in humans, but data are limited on the actual effects, the researchers said.

So they investigated whether adding a single, large dose (14 g) of a high-antioxidant spice blend to a 1,200-calorie meal had any effects on markers of antioxidant activity and metabolism. That spice dose is equivalent to the amount of antioxidants in five ounces of red wine or 1.4 ounces of dark chocolate, they said.

They enrolled six healthy but overweight men ages 30 to 65 in a crossover trial. First the men ate a control meal consisting of coconut chicken, a white rice dish, cheese bread, and a dessert biscuit.After at least a week, the men ate a second, spicy meal, in which the chicken was transformed into chicken curry, with a side of Italian herb bread and a cinnamon biscuit.

West and colleagues sampled participants' blood before each meal and every 30 minutes for almost four hours afterward.

They found that the addition of spices significantly reduced insulin and triglyceride responses to the meal, although there were no effects on glucose.

Compared with the plain meal, insulin levels fell 21 percent and triglyceride levels dropped 31 percent after the spicy meal.

"These significant effects were likely a result of the high concentration of phenolic antioxidants in spices," the researchers wrote.

Indeed, the researchers found that hydrophilic ORAC levels -- that marker of antioxidant activity -- were 13 percent higher across all time points after the spicy meal, although lipophilic and total ORAC -- two other antioxidant activity markers -- were not changed overall.

Yet another marker, ferric reducing antioxidant power, was doubled after the spicy meal, though there were no differences in plasma thiol concentrations.

The spicy meals were well tolerated, the researchers said, with no gastrointestinal effects, and participants' satisfaction was similar whether the meal was spiced or not.

West and colleagues wrote that the triglyceride findings are consistent with results seen with tea, and potential mechanisms may include delayed gastric emptying and direct inhibition of pancreatic lipases.

The insulin findings were consistent with earlier studies of cinnamon, they said, and it may be that the polyphenols in spices improve insulin sensitivity.

The study was limited by its small sample size, and further work is needed to characterize the effects in larger samples and more diverse populations, the researchers said. Future studies also should assess whether smaller doses of spices are associated with similar changes.

Also, they noted, spices should be looked at separately to tease out individual effects.

They concluded that incorporating spices into the daily diet "may help normalize postprandial disturbances in glucose and lipid homeostasis while enhancing antioxidant defense."