The dreaded spring allergy season is here, and this year's forecasts say it could be the worst one in years. But allergy sufferers may be surprised to learn that what's in their gut may be partly to blame for all the wheezing and sneezing.

"Researchers found that there seemed to be a different type of population of bacteria in children who had allergies versus those who didn't," microbiologist Jason Tetro told North by Northwest's Sheryl MacKay.

Tetro adds that a few years later, a study in Finland found that there are more good bacteria (symbionts) in healthy kids without allergies. In those who suffered allergies, there was an increase in bad (or pathobiont) bacteria.

"Over the years, there's been more and more studies that show...if you suffer, you have more bad bacteria than if you don't."

He says it comes down to the immune system when it comes to choosing how it deals with bacteria in the body. There are three categories it uses to assess how to treat pathogens.

1. Tolerance: "It simply means do nothing. The bacteria is either friendly or harmless."

2. Combat: "It's essential when we have an infection and we try and destroy it."

3. Sensitivity: "This one is a bit freaky because the body recognizes that it's not something it can kill, but it has to find a way to get rid of it without using combat."

The way it does that, he says, is it tries to flush it out by creating more mucus. The body tries to prevent it access by tightening up blood vessels and the lungs.

It also affects one's mentality. Like the fight or flight symptom, it increases fear and anxiety. "Unfortunately in some cases this scenario can have drastic consequences, such as a peanut allergy."

Tetro explains that bacteria have to work with the immune system in order to thrive. It's the good bacteria that promote tolerance, but it's the bad bacteria that cause issues.

While the bad bacteria don't want the body to go into combat mode, the immune system is unable to tolerate it like it would good bacteria.

Therefore, it causes the body to enter sensitivity mode.

"When that happens, we come into contact with allergens, and instead of being able to tolerate them, we end up being afraid of them."

First year of life is key

The main way to prevent bad bacteria buildup says Tetro is to have the body build up good bacteria in its place. The first year of life is essential for that process.

"It's really fascinating that the first year of life is the most important when it comes to allergies. It seems like breast feeding, getting kids out to play in the dirt and getting exposed to friendly bacteria is the answer," says Tetro.

He says that by subjecting young children to an increase in good bacteria (such as playing outside) early, there is proven evidence that the buildup of the bad bacteria decreases.

Tetro says it's all part of the hygiene hypothesis, which postulates that the seemingly paranoia of having to sanitize everything that humans interact with isn't allowing bodies to build up immunities.

He says the solution can be very simple for young children to combat this.

"Let them eat dirt, is what I always say."

To hear more, click the audio labelled: Microbiologist explains importance of good vs bad bacteria.