Breakdown of Er kann Laktose nicht vertragen.
er
he
nicht
not
können
can / to be able to
die Laktose
the lactose
Questions & Answers about Er kann Laktose nicht vertragen.
Why is nicht placed right before vertragen instead of after the modal verb kann?
In sentences with a modal verb (kann) and an infinitive (vertragen), nicht moves to the end of the clause, sitting right before the infinitive. This happens when nicht negates the whole action rather than a single specific word. It shows that 'tolerating' is what he cannot do.
Why do we use nicht here instead of keine, since Laktose is a noun?
You could absolutely say Er kann keine Laktose vertragen—both are perfectly correct! Using nicht emphasizes the verb (the inability to tolerate), whereas keine negates the noun. In German, when a noun and a verb form a tight, logical unit (like 'tolerating lactose'), you will often see nicht placed right before the final verb to negate the whole concept.
What exactly does vertragen mean in this context?
Vertragen generally means 'to tolerate', 'to endure', or 'to stomach'. It is the standard and most natural verb to use in German when talking about food allergies, dietary intolerances, or even handling alcohol (like Ich vertrage keinen Alkohol).
Could I express this without the modal verb kann?
Yes, you can simply say Er verträgt Laktose nicht (or Er verträgt keine Laktose). Using kann just adds a slight emphasis on his physical ability to process it, but the core meaning in everyday speech is exactly the same.