Can New Wristband 'Sense' What You're Eating? | LiveScience

This article is a bit dated but the skepticism remains,,,

However, some were skeptical about the device's claims.

While it is plausible that a spectrometer could detect different nutrients in a blood sample, the AIRO device would be limited in several ways, said Michelle MacDonald, a clinical dietitian at National Jewish Health hospital in Denver.

For one, the device would need to sense through the skin "into the various streams of blood that happen to be flowing in the small vessels in your wrist," MacDonald said.

"Most of the nutrients in the foods you eat are absorbed by the gut, then sent to the liver first and foremost through the portal vein for absorption and processing. What ends up in your wrist is a distant remnant of what is absorbed from your meal," MacDonald said.

In addition, the spectrometer would need to be relatively cheap in order to keep the device cost affordable, which would limit its sensitivity, MacDonald said.

"AIRO provides a highly questionable nutrient analysis at best," MacDonald said.

MacDonald said whatever the device could detect "cannot be valued any better or more than making a value judgment of the ingredients on the food label."
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Can New Wristband 'Sense' What You're Eating? | LiveScience