Colour requirements at work
Short answer: If the uniform has a set colour, the underwear has to be chosen so it does not show through. Under a light uniform that means skin tone rather than white.
The uniform decides the layer beneath
If the uniform is light, white underwear shows clearly through. If it is dark, light underwear shows at the neck and cuffs. Choose a layer underneath that sits close to either the skin or the uniform's colour. See bamboo undershirts for women.
Socks and trousers
If the workplace requires dark trousers, choose socks in the same tone. That is the simplest rule and applies even when only the trousers are specified. See bamboo socks for men.
What you can control yourself
A thin layer of bamboo viscose under the uniform absorbs the sweat and lets the uniform be worn for several days. That is the one thing you can choose freely, however strict the rules are. See bamboo undershirts for men and bamboo underwear for women.
Frequently asked questions
What if the uniform is white
Choose underwear in a skin tone. White under white is the most visible combination there is.
Can the underwear be patterned
Under dark clothing yes. Under light clothing patterns show most clearly of all.
Does a layer underneath help against sweat marks on the uniform
Yes, noticeably. The layer absorbs the sweat before it reaches the outer face.