I suggest the Khmer to fix the problem of iodine deficiency. Forget about drinking lemonade. Forget about having your skin pretty, iodine deficiency makes you dumb for the whole life.
You can get recommended amounts of iodine by eating a variety of foods, including the following: Fish (such as cod and tuna), seaweed, shrimp, and other seafood, which are generally rich in iodine.
But Khmers cannot afford to eat cod, tuna, seaweed, shrimp and other seafood. Khmers are dirty poor. You should see what a typical Cambodian garment worker eat for lunch, costing an average of 50 cents a meal. It's mostly rice with vegetables and little to no meat. Such a life.And that's why Khmers are inferior to Vietnamese.