\documentclass[10pt]{IEEEtran}
\usepackage{longtable}
\usepackage{balance}
\usepackage[english]{babel}
\usepackage{blindtext}
\usepackage{supertabular}
\usepackage[table]{xcolor}

\newcommand*{\restorecolumns}{}
\makeatletter
\newenvironment*{OneColumn}{%
	\if@twocolumn
		\balance
		\let\restorecolumns\twocolumn
		\onecolumn
	\else
		\let\restorecolumns\@empty
	\fi
	\ignorespaces
}{%
	\nobalance	
	\restorecolumns
	\ignorespacesafterend
}
\makeatother


\begin{document}
\blindtext

\blindtext

\begin{OneColumn}
 	\begin{longtable}{@{}m{.1\columnwidth}l@{}}
	\caption{This is a test table}
	\endfirsthead \\
	& continued from previous page \endhead  \\
 	& \hspace{.4\columnwidth} continued on next page \endfoot  \\	
	\endlastfoot \\
	\hline 
	& Item 2 \hspace{.3\columnwidth} Item3 \\\hline 
	Item1
 	& \rowcolors{1}{white}{gray!20!white}
	\begin{tabular}{m{.2\columnwidth}m{.5\columnwidth}} 
		item 2 & 
		\blindtext \\
 		item 2 & 
 		\blindtext \\
 		item2 & 
 		\blindtext \\
	\end{tabular} \\\hline
	Item1
 	& \rowcolors{1}{white}{gray!20!white}
	\begin{tabular}{m{.2\columnwidth}m{.5\columnwidth}} 
		item 2 & 
		\blindtext \\
 		item 2 & 
 		\blindtext \\
 		item2 & 
 		\blindtext \\
	\end{tabular} \\\hline
	Item1
 	& \rowcolors{1}{white}{gray!20!white}
	\begin{tabular}{m{.2\columnwidth}m{.5\columnwidth}} 
		item 2 & 
		\blindtext \\
 		item 2 & 
 		\blindtext \\
 		item2 & 
 		\blindtext \\
	\end{tabular} \\\hline
	\end{longtable}
\end{OneColumn}

\blindtext

\end{document}