How Do You Avoid GM Foods If They Aren't Labeled?

In 2003, Dean Metcalfe from the NIH's National Institute of Allergy and Infectious Diseases published a mini-monograph in the government's peer-reviewed journal Environmental Health Perspectives:

Introduction: What Are the Issues In Addressing The Allergenic Potential Of Genetically Modified Foods?

It's a quick read. In it, I saw:

"It is inevitable that application of this technology has raised a number of fundamental concerns, including the consequences of reporter genes, the spread of resistance genes to surrounding plants, the use of suicide genes to prohibit reuse of seed from engineered plants, and finally, whether these altered plants may be allergenic."

I thought that sentence summed up nicely some of the emerging problems with these crops.

As to possible allergenic traits, Metcalfe said:

"Much of the need to address the safety of modified foods is because currently there is no available means to cure a given individual of an immediate reaction to food. The strategy for protection of a sensitive individual involves instruction on dietary avoidance of the foods in question."

How do you instruct a sensitive individual to avoid foods that may be causing their allergic reaction if those foods aren't labeled?
________The photo is for a product produced in the Netherlands. The European Union requires labeling of genetically modified foods. As of this date, the US does not.