I've always heard that natural potions/mixtures cannot be patented.

I asked my friend who works in the US Patent office about this, and he told me "yes, they can be patented and gave me a couple of examples and where to find them.

He gave me a couple of examples:

Herbal remedies for treating allergies and asthma

Herbal tonic composition that improves respiration, aids in the elimination of toxins and improves overall vitality

He said that patents involving natural ingredients would be in class 424, and subclasses 725-299

here is a search for ccl/424/725
you can see a lot of patents for natural formulas.

I believe the way it works is that the individual ingredients cannot be patented, but you can patent your recipe of two or more ingredients