There's a rather simple way to discern if someone of the Caucasian persuasion is eating enough vegetables. By just looking at the color of their skin, you can tell if they're eating enough fruits and veggies by observing an organic class of pigments called carotenoids.
As ScienceAlert points out, you're already familiar with this phenomenon even if you don't realize it:
You've probably already seen the power of carotenoids in the colour of other animals that eat them - mostly birds. Goldfinches and their yellow colouring, cardinals and their red, and flamingoes and their pink are all the result of carotenoids.
So it is that carotenoids can also affect the pigment of human skin. Excessive consumption of carotene can turn the outer layer of the skin orange, resulting in a jaundice-like, or orange-tinged appearance.
I remember when I was in elementary school, my mom ate a ton of carrots on a regular basis. I mean, I don't know for certain that it was an actual ton, but it sure seemed like it. She ended up going to her doctor because her skin became more orange, and thought she had liver disease... When in fact, she'd just been eating a ridiculous amount of carrots. (NOTE: This orange skin phenomenon is not to be confused with the "leader" of our country. That's a whole other thing involving tanning beds.)
ScienceAlert says that this condition is known as carotenoderma, and explains it in further detail:
This problem is known as carotenoderma, and you'd have to eat a lot of high-carotenoid foods over an extended period of time. According to a 2003 literature review, it takes 4-7 weeks for visible changes to appear.
But no matter the amount of vegetables you're eating, there's a detectable change in skin pigmentation, not necessarily with the naked eye but non-invasive spectroscopy - and this could be useful to health practitioners.
The scientists for this study used a rather small sample size of just 30 men living in Australia.
"The aim of our study was to determine whether there was a connection between fruit and vegetable consumption, carotenoid intake and yellow skin colour in young Caucasian men, as Australian men are typically known to consume less fruit and vegetables than women," said dietician Georgia Bixley from Curtin University in Australia.
"We were able to find this connection through a process called reflectance spectroscopy (RS), an emerging technique which measures the colour and intensity of reflected light on the skin pigments."
The findings are consistent with an earlier study of 100 women.
"Our research could play a key role in identifying people who have a low consumption of fruit and vegetables, and better understand their higher risk of chronic diseases," said nutrition scientist Karin Clark, also of Curtin University.
"By conducting further research into this connection, it could open up the possibility of being able to predict someone's fruit and vegetable intake from their skin colour, rather than relying on them to remember every meal they eat."
So eat your fruits and veggies, people!