Health officials in the Land Down Under are cracking down on a popular supplement. Australia’s Therapeutic Goods Administration (TGA) announced this week that it will roll out new sales restrictions and labeling rules for vitamin B6 products, warning that prolonged high doses can cause potentially dangerous side effects. “You can have too much of a good thing,” Dr. Oliver Jones , a chemistry professor at RMIT University in Melbourne, who was not involved in the new policy, said in a statement .