The National Institute for Neurological Disorders and Stroke reports that food and ingredients in foods play a part in about 50 percent of migraine headaches. The Institute reports that the cause of headaches is often complex. Sugar consumption may be one of the factors that lead to headaches, but it is one over which we have some control.
The pain that is a headache results from loss of oxygen due to constricting arteries around the brain. This constriction is often caused by sudden changes in levels of blood glucose, the food carried by blood to brain cells along with oxygen. Under normal circumstances, delivery of glucose is kept constant by insulin created in the pancreas; but when the system fails, arteries cramp up, trying to force more flow. A headache is the brain's signal that it is in distress.
Sugar is a simple carbohydrate; it translates immediately into blood glucose. Refined sugar, fructose in fruit, lactose in milk and the corn syrup we put on pancakes are all simple carbs. Complex carbs--whole grains like flour, oatmeal and rice as well as many vegetables--take longer to transform into glucose and enter the blood gradually, over a longer period of time.
Cells with insufficient glucose are unable to process food and oxygen in a condition called hypoglycemia. The National Headache Foundation (NHF) says that migraine sufferers often crave carbohydrates before or during an attack, a sign of low blood sugar. Hypoglycemia is the "crash" after an overdose--often consisting of a large portion of simple carbs like sugar--that forces arteries to spasm and withhold oxygen from brain cells, resulting in the painful cramping we call a headache.
The AHA reports that Americans consume nearly 355 calories worth of extrinsic and intrinsic sugars, much of them in simple carbohydrate form per day. Considering that 100 to 150 calories per day would be a sensible amount, this means that Americans routinely engage in the kind of sugar feast that leads to hypoglycemia. According to the NHF, the result can be "lightheadedness, weakness, headache, sweating, and change in level of consciousness if the condition is severe enough."
Signals and Consequences
Although sugar does not cause headaches directly, its overconsumption triggers the process that causes them. It makes sense to control how much sugar is in the food we consume if only to lower the risk of headache. With sugar intake controlled, headache pain may provide an early warning to serious conditions related to uncontrolled blood sugar levels, like stroke or diabetes.