The only 'suplement' I carry myself is Nutribar Vanilla Shake powder in a ziplock bag. Its intended as a meal replacement and is OK for that but I usually mix up a batch and use part as a milk replacement on cereal and drink the balance at the first break during the day.

There's a number of equivalent products on the market and they all travel well, don't absolutely need refrigeration, and provide vitamin and mineral supplements as well as calories.