Nature Product gets just over 1,000 searches on Google, not 2.8 million!
When you're checking an expression containing 2+ words, always put it in quotes first.
If you don't, you'll get a count of all the results with the word "nature" and "product" SOMEWHERE on the same web page, which is ridiculously misleading!
For instance, if you search for sex yawn you get 59,000 results. However, with the quotes you get just 45 results, and these are due to justapositions such as "... sex. Yawn ..." since Google doesn't record punctuation but treats it as spaces.
It's dangerous to rely on search engine results as a guide to registering domains unless you REALLY understand what you are doing.