Gwyneth Paltrow controls her children's diets because her son has eczema.

The 40-year-old actress has hit back at her critics for calling her a ''bad mom'' after she recently revealed that her daughter Apple, eight, and son Moses, seven, have gluten and dairy free diets but she insists it is only because he suffers with inflamed and irritated skin.

The blonde beauty, who released her new healthy eating cookbook 'It's All Good' last week, said: ''What it is, is that my son [Moses] has very bad eczema and he's allergic to gluten and he's allergic to cow dairy. I try at home to make everything gluten-free for him because the difference in his comfort is unbelievable when he's sticking to what he's meant to be eating.''

The 'Iron Man 3' star, who is married to Coldplay frontman Chris Martin, also claimed that their children are very normal and enjoy occasional treats.

She told Dr. Mehmet Oz on 'The Dr. Oz Show': ''I don't know where they get some of this stuff! They say I don't give my kids carbs, and I'm feeding them seaweed...I have no idea. But they eat Oreos, too, and they're normal kids.''

Gwyneth recently revealed she treats her children with a 'Coke of the week' to give them a break from their healthy-eating regime.

She said: ''They love a brown rice stir-fry, but they also love their 'Coke of the week'.

''My daughter gravitates toward fresh fruit and raw nuts but will inhale a bag of hot Cheetos at the airport. It's all about balance.

''I try to make sure that what is on their plate at home is nutritious and tasty, and then I loosen way up on the reigns when we are out.''