Science Buddies: "Ask an Expert"

I am measuring the carbon dioxide output in expired air using the method you describe watching the colour change when pH indicator is added to water ie from blue to yellow when breathing through the homemade respirometer. What I am wondering is whether i can use this to measure the effect of different pre-race meals. i know that when you eat carbohydrate it is broken down to carbon dioxide and water and energy is produced. I know that the carbon dioxide dissolves in the water to give carbonic acid with makes the blood more acidic and that when blood reaches the lungs the carbonic acid is converted to carbon dioxide. Do you think it the amount of carbon dioxide in the air breathed out would be effected by the amount and type of carbohydrate eaten?
Many thanks for your help.

Hi Peter,

Good job on getting your background information about how carbon dioxide is generated from carbohydrates.
I think it would be interesting to use your system to assess different pre-race meals but you might to include time after eating as one of your measurements and not just amount of carbon dioxide. The reason for this is because the body converts all foods into glucose (a simple carbohydrate) before it breaks it down to get the final energy and carbon dioxide and water. So all of the food types (protein, fats, complex carbohydrates) will eventually generate glucose and then carbon dioxide, but some might take longer than others. So you might want to make sure to test some foods with easily converted simple sugars and others with more complex food types.

-Caroline