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Low-carb diets could lead to problems with roadside breath tests

| May 10, 2019 | Drunk Driving (DUI)

The ketogenic diets that have recently become popular in Virginia might fool the portable breath-testing technology used by most police departments, according to some scientists. While research into the phenomenon is sparse, individuals following low-carb diets have been known to find it extremely difficult to start vehicles equipped with ignition interlock devices.

These issues arise because ignition interlocks and portable breath-testing units rely on fuel cell technology that may not always be able to differentiate between ethanol alcohol present in the breath of individuals who have been drinking and isopropyl alcohol that is a byproduct of ketosis. Ketosis is the metabolic state that low-carbohydrate diets are designed to induce. The body goes into ketosis when its glucose stores have been consumed and the liver burns body fat to provide energy. Isopropyl alcohol is a byproduct of this fat-burning process.

Motorists who eschew carbohydrates need not be too concerned because the amount of isopropyl acid produced by ketosis is not sufficient to generate a blood alcohol concentration of .08 percent or higher even if breath-testing devices are fooled. The results of roadside breath tests are also not generally used in court to prove impairment in DUI cases. However, drivers on ketogenic diets who get behind the wheel after consuming one or two drinks could find themselves with some explaining to do if they get pulled over.

Diets low in carbohydrates are not the only factors known to cause misleading breath test results. Criminal defense attorneys dealing with drunk driving cases may ask defendants about their medical histories and examine police maintenance records carefully. This is because common conditions such as diabetes can influence breath tests.