There are large regional differences regarding the use of phosphorus (P) fertilizer in global crop production. Likewise, people's accesses to crop calories and exposure to water pollution differ largely among world regions. The use of P fertilizer is needed to meet agricultural requirement and solve these inequalities. We developed a multi-objective framework for optimizing P fertilizer use that considered water quality, food security and social equality. Different optimal objectives yield contrasting results for the geographical distribution of P fertilizer use, crop calorie production and social equality. Optimized P fertilizer use without recycling P management may pose a threat to global food security. Approximately 3 %-43 % of the current global crop calorie production may be decreased, and inequality in access to crop calories may also increase. Overall, although a multi-objective framework to optimize the use of P fertilizer reduces crop calorie yield, it can help intergenerational equality of P fertilizer use and improve water quality.