Question: In my dictionary there's both "sana" and "saniga" for "healthy". What is the difference? Can I simply always use "sana"? If not, why?

Answer: 
*[sana](http://vortaro.net/#sana)* is the state of a person: *Li estas denove sana kaj do povas reveni al la laboro* - *Ĝenerale mi estas sana persono*

*[saniga](http://vortaro.net/#saniga)* ("making healthy") is the quality of something that leads to health: *La medikamento estas saniga* - *La ferioj estis kvazaŭ sanigaj por mi, mi regajnis energion*

Traditionally, both *sana* and *saniga* can also mean "furthering, supporting health", e.g. *sana manĝaĵo*, *sanigaj banoj*. For this third meaning there is also a special word *[salubra](http://vortaro.net/#salubra)*, but it seems not to be used very often.
Ankaux, jen eksemplo de la diferenco.

La vundo sanigxas- The wound heals.

La kuracisto sanigas la vunditon- The doctor heals the wounded person.