Here's a method I've cooked up and have been using for a while to get health supplements/vitamins from WF.
WF has always had a really lenient return policy. You can return a mostly drank bottle of water for a full refund if you want. We can leverage this to get our health needs taken care of.
1 - Buy supplements, ideally with cash to reduce the possibility of tracking. For extra plausible deniability, buy a snack or something along with the supplement you want for free. Keep your receipt.
2 - Use up the supplements or empty them into another container (for pills, remember to keep the gel pack because pills WILL get moldy without them.)
3 - Refill the original container with something similar to what was originally inside. If you're like me, you probably have a bunch of old pills of stuff that you don't use anymore, just put some of that in the pill bottle. For liquids, you can just fill it up with water.
4 - Return the items. You can say they didn't work for you or caused a negative reaction or something like that.
I have done this many times and I think they have only looked in the bottle once. You can also do this with protein powders and body wash/shampoo if you have something similar to replace it with. You could probably even put dirt in a protein powder container but I've never been bold enough to try that.
If you don't have any pills to use, try asking friends or even on Craigslist if anyone has any extra pills they need to get rid of. Get creative.
This isn't the most lucrative strategy, but it can come in handy if you're buying supplements/vitamins already, or want to try out some stuff to address your health concerns on the dime of the richest man on earth.
Other stores I've tried had me sign a form with your phone number when I've returned supplements. You can still do it, but they track it more closely than WF. WF also has a 90 day return policy which is very convenient for this sort of stuff.