Washington, Sept. 28 -- : Endorsing the body butter of her brand 'Goop,' 'Iron Man' actor Gwyneth Paltrow marked her 48th birthday with a bold nude picture of herself on Sunday (local time).

The 'Goop' founder took to Instagram to share a picture of herself wearing nothing "but her birthday suit," and thanked fans for all the birthday wishes in the caption.

The picture features, the 'Contagion,' actor posing naked amid a lush green background near a tree with a bright smile on her face.

"In nothing but my birthday suit today... thank you all so much for the birthday wishes and thank you to @goop's insanely amazing brand new body butter for making me think I can still get my kit off," she wrote in the caption.

Fans and friends of the ...