Grammar girl here, listen to this sentence from a news story about whether vegetable oils

can really lower your cholesterol as much as people say they can.

We're often told to substitute saturated animal fats for healthier vegetable oils.

You might be thinking I'm going to comment on the use of healthier instead of more

healthful, but I'm not.

Healthier is just fine and you can find out more about that usage question in the link

I'll put in the transcript, or in my book 101 Troublesome Words, you'll master in

no time.

Whoops, I guess I did comment on healthier after all, but what I actually want to talk

about is the verb substitute.

So back to the sentence with substitute.

We're often told to substitute saturated animal fats for healthier vegetable oils.

Now here's another sentence with substitute, which I got from the corpus of contemporary

American English.

If every American substituted something meatless for one chicken dish every week, it would

save as much carbon dioxide as taking 500,000 cars off the road.

Did you hear the difference?

In substituted saturated animal fats for healthier vegetable oils, the verb substitute has the

pattern substitute old for new saturated animal fats for healthier vegetable oils.

In substitute something meatless for one chicken dish, the verb substitute has the pattern

substitute new for old, something meatless for one chicken dish.

What's going on here, which one is right?

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