Fish oil is best taken after dietary fat (preferably an isolated fat like butter or olive oil) has been consumed, it enhances the absorption. Although that's annoying because taking fish oil in the middle of a meal or afterward can kind of kill the eating experience. Perhaps some fat and fish oil at the same time at the beginning of the meal would work better if the first option seems undesirable.
Then I have heard that probiotics are better taken on a full stomach because the stomach is very acidic before a meal and it can kill them. Not sure if that's true but throughout evolution probiotics were always consumed with food. Multi-vitamins again are usually better consumed with food in case they include fat-soluble vitamins.
When in doubt I usually defer to the basic primal principle of "mmm mmm fat".
Stabbing conventional wisdom in its face.
Anyone who wants to talk nutrition should PM me!