DENVER -- Processed foods are convenient and plentiful. Many of us eat lots of them.

Megan Wiedel was no exception. Every day she ate foods from boxes and bags, foods she thought were healthy like low fat yogurts, soups, breads and occasional diet sodas. But, after eating them she started noticing nagging stomach aches. They got progressively worse.

"It was pretty sharp abdominal pain and a lot of days it was pretty debilitating," said Wiedel. That pain was often matched with headaches and overall malaise.

After trying numerous over the counter remedies with no improvement, Wiedel went to her doctor.

"He asked, 'do you eat a lot of processed foods?' I said, 'well kind of.' Then I realized that almost anything I ate was from a box or bag," said Wiedel.

Aurora physician, Dr. Gerard Guillory is Wiedel's doctor. He said he firmly believes many of us suffer from sensitivities to food additives like monosodium glutamate, or MSG. He also believes it should be removed from the food shelves.

"There is a cumulative, toxic effect that can be seen," said Guillory.

MSG is a chemical that creates that salty, sweet taste in most processed foods.

"It's kind of like an aphrodisiac for taste buds. So, it is added to everything to try and make it taste better," said Guillory. He believes this is the source of Megan's health concerns.

Studies have shown that anywhere from three percent to 30 percent of us can't process free glutamic acid, the reaction trigger created after consuming MSG.

Known often as monosodium glutamate toxicity syndrome, the side effects can be harmful.

Stomach aches, headaches, migraines and difficulty focusing are some common complaints after eating foods containing free glutamic acid.

"Glutamic acids stimulate receptors in the brain. They can cause a whole host of problems. The list of reactions reads like a list of side effects of psychiatric medication," said Guillory.

The advice for Wiedel was to eliminate monosodium glutamate from her diet.

That was a task that sounded easier than it really was. Megan started reading every food item label and found something interesting.

"A lot of foods will say MSG free and then you look at the label and the pseudonyms are one after another. It can be hydrolyzed soy protein then natural flavors and spices," said Wiedel.

The Food and Drug Administration recognizes MSG as a safe food additive and requires food producers to label it accurately. But, many other ingredients can also contain free glutamic acids as a result of the manufacturing process.

Identifying these items on food labels can get quite tricky.

"You really need to understand all the different names that MSG goes by to try to avoid it. Ingredients like hydrolyzed vegetable protein, modified food starch and natural flavors can often contain MSG," said Guillory.

In addition to those ingredients, Wiedel also eliminated ingredients like hydrolyzed soy protein, yeast food, textured protein and sodium caseinate from her diet.

Whole, natural foods replaced the processed staples.

"My meals have become more simple. I'm not spending a lot to over flavor them. I can eat all of the same things, but they are more fresh," said Wiedel.

Something worked. The MSG is gone. So is her pain.

"I just feel more energetic and more like myself after I eat," said Wiedel.

Guillory also suggests patients eliminate aspartame, an artificial sweetener from their diets.

Aspartame stimulates the same part of the brain and can cause similar side effects to those of MSG.

Guillory says together, these additives can pack an unhealthy punch.

"It has a cumulative effect. You have some aspartame in a diet soda and some soup that has MSG. That has an additive effect. The next thing you know you have a headache or worse," said Guillory.

To read more about MSG and aspartame sensitivites and to see a list of other sources of MSG, visit MSG and Aspartame Sensitivities.

To read more about Guillory's MSG Studies, visit The Care Group, P.C..

To read more about food labeling and the Food and Drug Administration, visit U.S Food and Drug Administration.