Any from a big store like walmart, costco etc... There are random lab analysis done by independat labs on the big stores always trying to catch a good story. I have seen this in my journals. If you eating large amounts of calories, I strongly believe that you should take one tab twice daily. Micronutrients within these vitamins do help transport, digestion and other processes. The studies are all over the place. I take omegas for obvious reasons and Im getting past your question (sorry). Big store, not internet.