Brad & Angelina Worried About Twins' Health

Angelina Jolie Vivienne Marcheline

Brad and Angelina's twins have been in hiding lately, and health problems are why.

Brad Pitt and Angelina Jolie have maintained a noticably low profile with their 11-month-old twins Knox and Vivienne—especially compared to the mega-limelight presence of the other four mini-celebrities in their brood—and now reports explain why. According to Life & Style, the babies are suffering "serious" digestive disorders that are affecting their growth and eating patterns.

Their systems are "hypersensitive," according to a family insider. Knox spits up after almost every meal, and Vivienne suffers from allergies. Even on a gluten-free, lactose-free diet, she's reportedly underweight and not improving. 

Speculations about the twins' health have surfaced recently among the public, as the only mainstream photos of them that exist date back to last January when they were being rushed through an airport in Tokyo.  Some reports suggest that Brad and Angie have turned to genetic testing in search of the root and solution, and until they find the results, they'll keep the babies in private. "Because of their delicate state, Knox and Vivienne need to be kept away from anything they could possibly be allergic to," the family insider explains. "That's a lot easier to do when they're home and in a controlled environment."

Knox and Vivienne will celebrate their first birthday on July 12...with a gluten-free cake.