I can hardly think straight, never mind keep food down.

我都没办法思考，更别说吃东西了。

youdao

She's had some water but she can't keep any food down.

她喝了点儿水，但一吃东西就吐。

《牛津词典》

Alinovi said the conflict could keep food production down, despite the new rains.

Alinovi说尽管有雨，这些冲突会让粮食产量下降。

youdao

If a woman cannot keep any food down, she should consult her GP.

BBC: Pregnancy wreaks havoc on the female body.

Hyperemesis gravidarum can leave expectant mothers unable to keep food or liquids down.

BBC: The Duke and Duchess of Cambridge

We're also encouraged to keep our food miles down - the distance our meals have traveled and their means of transportation add to the carbon dioxide emissions contributing to climate change.

CNN: Skip the fast food and go slow