I think its just the standard cya statement you'll find on ANY otc med or supplement.
I take them, and they DO have the added benefit of increasing supply for me. Another board I'm on where many nursing moms take it had mixed results.
In that vein, start slowly with the dosage. I started out taking too many, and ended up engorged with a series of plugged ducts until I figured it out. The bottle probably lists dosage at 2 capsules. But if you bought the oil, dosage would like be 1 TBSP. We figured it out, and the equivilant in capsules would be 14!!! I take 9 a day, split into 3 doses. And I don't take ANY after about 5 pm, since dd sleeps all night, and I don't need milk at midnight.
It'd be interesting if you start them if you notice the supply increase--let us know.