Fibromyalgia: The Diet Connection (cont.)

"There is a pain receptor in the nervous system known as NMDA," says McNett. "When pain turns from acute to chronic, it involves opening the NMDA pain receptor. Aspartame, which is classified as an excitotoxin, helps to stimulate this event." He also says people with fibromyalgia appear to already have overly active NMDA pain receptors, making them more susceptible to the stimulation.

In one study published in the Journal of Rheumatology in 2006, experts found patients with fibromyalgia did have an increased expression of NMDA receptors in their skin. This indicated a general increase in activity of peripheral nerves.

Fibromyalgia: Seven foods to avoid continued...

Holtorf says aspartame may play a role in stimulating those nerve pathways. Then he adds that for some people, "cutting it out of their diet can have a dramatic impact on pain."

That appeared to be the case for patients in one small study published in the Annals of Pharmacotherapy in 2001. Researchers found that, when patients with fibromyalgia avoided aspartame as well as the flavor enhancer MSG, they felt better overall.

Other artificial sweeteners such as Splenda, saccharin, and stevia do not appear to have the same effect as aspartame.

2. Food additives including MSG (monosodium glutamate) and nitrates. MSG is an additive or flavor enhancer that's found in many processed and frozen foods and in some Asian cuisines. Experts say it can intensify pain symptoms in many individuals. Like aspartame, MSG is classified as an excitotoxin and has the same potential for affecting NMDA receptors.

The same is true, says McNett, for foods containing preservatives such as nitrates, commonly found in lunchmeats like ham or bologna or in bacon.

"A lot of people who don't have fibromyalgia can't tolerate nitrates or MSG very well. But one of the hallmarks of this condition is that it amplifies unpleasant reactions," McNett says. "So a stimulus that some people would find mildly unpleasant becomes very unpleasant in those who have fibromyalgia." Cutting these ingredients out of the diet, he adds, usually helps.

3. Sugar, fructose, and simple carbohydrates. There is no clear evidence that cutting out simple carbohydrates -- like sugar, cake, or white bread -- will have an impact on fibromyalgia. What it can do, though, is reduce symptoms of chronic yeast infection -- a fungus that thrives on sugars and may be a secondary condition contributing to the pain of fibromyalgia. This theory, however, is still being debated by experts.

"Cutting out sugary foods, particularly high fructose corn syrup, can make a difference in these patients," says Holtorf. "And that's independent of any weight loss that might occur when they stop eating these foods."