In a series of studies designed to define the role of dietary macronutrients in the initiation of arterial inflammation that predisposes a person to atherosclerosis, researchers at the US University at Buffalo have found that a high intake of glucose, or eating a high-fat, high-calorie fast-food meal can, perhaps not totally surprisingly, cause an increase in the blood's inflammatory components. On a positive note, however, the scientists also found that the antioxidant vitamins E and C can nullify this inflammatory response.
"A meal high in calories and fat caused an increase in inflammatory markers that lasted three to four hours," said Paresh Dandona, senior author of the studies.
"We think the influx of macronutrients, such as calories, fat, protein, carbohydrates and water, may alter cell behaviour and that genes are activated to produce more powerful enzymes and mediators that are potentially more damaging to the lining of blood vessels. Obese persons may have an ongoing abnormality of the white blood cells and the lining of blood vessels."
"On the other hand, we found that one way to render an 'unsafe' meal 'safe' is to include antioxidant vitamins," Dandona said. "The pro-inflammatory effect of glucose is stopped if right at the outset you give vitamins E and C."
The 'meal' study was conducted with nine subjects who ate a 900-calorie breakfast - an egg-and-ham sandwich and hash browns from a fast-food restaurant - after an overnight fast. Blood samples were taken before eating and at one, two and three hours after eating to determine the concentration of oxygen free radicals, which can begin the inflammation cascade by injuring blood vessel linings, and of several blood mediators of inflammation.
Results showed a mean increase of free radicals over baseline of 129 per cent, 175 per cent and 138 per cent at the three sampling times, respectively. Levels of several pro-inflammatory indicators also increased significantly, while the level of a factor that inhibits inflammation was reduced.
Four additional studies further defined the pro-inflammatory cascade initiated by an influx of glucose alone and of an infusion of fatty acids. These studies also showed that both sugar and fat caused a reduction in the ability of vessels to expand and contract in response to changes in blood flow, actions crucial for maintaining healthy blood pressure and blood flow to vital organs.
In a further study, eight subjects took 1,200 IU of vitamin E and 500mg of vitamin C before a glucose challenge, and on a subsequent occasion, took only glucose. Blood samples were taken before the challenges and at one, two and three hours after.
Results showed that levels of oxygen free radicals and two pro-inflammatory markers increased when glucose was taken alone, but did not increase when accompanied by the two antioxidant vitamins.