From section D, part vii: 'The world is yet to ensure x food for all.' 'The world' refers to a unique entity (Rule 8). 'Food' in this general context (food for all) is uncountable and unspecified, so no article.
Class 6 › English Grammar and Composition › Chapter 3: Articles: a, an, the › Topic: Introduction to articles: a, an, the
Aligned to the NCTB national curriculum.