Complex sentence: While Romania imports substantial quantities of grain, it is largely self-sufficient in other agricultural products and food stuffs, because food must be regulated for sale in the Romania retail market, and hence imports almost no food products from other countries.
Split into simpler sentences: While Romania imports substantial quantities of grain, it is largely self-sufficient in other agricultural products and food stuffs. Food must be regulated for sale in the retail market, therefore Romania imports almost no food products from other countries.