bp_document_get_download_content_type( string $file_path )

function bp_document_get_download_content_type( $file_path ) {
	$file_extension = strtolower( substr( strrchr( $file_path, '.' ), 1 ) );
	$ctype          = 'application/force-download';

	foreach ( get_allowed_mime_types() as $mime => $type ) {
		$mimes = explode( '|', $mime );
		if ( in_array( $file_extension, $mimes, true ) ) {
			$ctype = $type;
			break;
		}
	}

	return $ctype;
}