bp_media_allowed_mimes( Array $mime_types )

function bp_media_allowed_mimes( $mime_types ) {

	//Creating a new array will reset the allowed filetypes
	$mime_types = array(
		'jpg|jpeg|jpe' => 'image/jpeg',
		'gif'          => 'image/gif',
		'png'          => 'image/png',
		'bmp'          => 'image/bmp',
	);

	return $mime_types;
}