That's great about the Lactaid!
Well, it's a little complicated, especially with oats.
I ate oats all my life, then one day started getting sick eating them, as in Celiac sick.
Apparently, there's actually a portion of the population who have an additional problem with oats, so I assumed that was the case with me. It wasn't as if Drs. were forthcoming with advice.
So, I stopped eating oats.
Then, a few years ago, I read about a company who said that when their son was born Celiac, they decided to make *truly* gf oats and products.
That's when I learned that the reason that so many Celiac's can't eat oats, is 2-fold.
1 - A lot of times other plants, ie: wheat, sprout among the oats, cross contaminating them.
2 - There's cross contamination in the big bags that hold them, from the tires of the harvesting equipment, and sometimes on the processing equipment.
This company claimed to check all of that, so I took a chance and tried their product. I was fine! So, I stick to their oats only, since, like rice, it is so often contaminated, and not always with the knowledge of the people who grow/market it.
It costs more to test at different stages, from field to bagged oats, but really is worth it.
So, maybe the people who make the oat milk that Erin eats truly have a gf product.
But, yes, one more factor...Celiacs have different sensitivity levels. Some can eat a certain amount of parts per billion, while others cannot eat as much.
So, perhaps she can eat something with a little more parts per billion than someone else.
My suspicion is that the more repeat exposures that you had before being dx'd, the less you can handle later on.
Unfortunately, yes, a lot of lactose-free, and gf-free items are cross contaminated. I am not allergic to a lot of what I can't eat, such as corn based cereal, or rice based items, but I have a problem with their cross contamination, so have a more limited diet than I have to.
I look for these words to be really safe: Made in a dedicated (fill in the blank with gluten free, lactose free, etc.) facility. The word 'dedicated' is music to my ears.
I also look for items that state: free of the top 8 allergens, gluten, etc. as a starting point. That's not always for sure, but it's a good point to begin with. I write to companies, and ask specific questions.
I hope this helps? Ask anything that you need to know for Erin. I'm happy to help, if I can.
Love All Life; Thank You For Posting! :)