I do not use soy sauce because of the wheat content in it and use Tamari instead. Tamari is a type of Japanese soy sauce that is made without wheat and is therefore suitable for those with wheat allergies. It is made from whole soya beans, traditionally brewed and aged in wooden kegs. Tamari is dark in colour and has a rich flavour, making it useful in marinades and dressings.
Personally, I find this less salty then soy sauce and a great alternative to the dark soy sauce.