Use of ため with a negative verb in this sentence


In my textbook Multimedia Exercises for Basic Japanese Grammar I came across
this example sentence and I was completely puzzled:

> これは、かぜをひかないためのサプリメントです。

All I have studied and read so far emphasized ため cannot be used with negative
sentences, actually I had read an example that used 風邪をひかないように。。。

Why is ため used in this example? I googled to see if there were similar uses
with negative verbs and got one Japanese page with this:
忙しい人たちの風邪をひかないためのTIPSをリサーチ.

Is it being used because of the の particle after ため? I'm very confused.




As you suggest, the following sentence does sound awkward.

> かぜをひかない **ために** 、このサプリメントを飲んでいます。

The reason is that かぜをひかない is not something you actively do, and therefore,
not suitable as a purpose.

The sentence below with ように, which denotes a desired state rather than a
purpose, sounds much more natural.

> かぜをひかない **ように** 、このサプリメントを飲んでいます。

If you still need to use ため, you should insert する as below so that the
adverbial clause describes what you actively do to achieve a desired state,
rather than the desired state itself.

> かぜをひかない **ようにするために** 、このサプリメントを飲んでいます。

However, this distinction becomes less strict in a noun-modifying clause
making かぜをひかない **ため** のサプリメント much more acceptable, although some might find
it a bit informal and still prefer かぜをひかない **ようにするため** のサプリメント.

