Hi Fiana, I've OVCA Stage IIIb and have just finished my set of six chemo sessions. I'd actually asked my Gyno Onc this question and he was all for taking a multi vitamin and mineral tablet on a daily basis. Your mom is in the restaurant business and actually it will also be easier for her to throw together a fruit smoothie (can be anything eg banana, cherries, plums, grapes, blueberries - whatever she likes) in the blender and drink that every day which can be a real energy booster!
I was stage 3c and never stopped taking my multivitamin at any point in my treatment. I have taken one a day for years - with and without cancer. I posted a question a while ago about bing tired and most reported that it is not unusual.