From the article:

Billions of dollars are given and spent on aid and development by individuals and companies each year. Despite this generosity, we simply do not allocate enough resources to solve all of the world's biggest problems. In a world fraught with competing claims on human solidarity, we have a moral obligation to direct additional resources to where they can achieve the most good. And that is as true of our own small-scale charitable donations as it is of governments' or philanthropists' aid budgets.

...

Guided by their consideration of each option's costs and benefits, and setting aside matters like media attention, the experts identified the best investments: those for which relatively tiny amounts of money could generate significant returns in terms of health, prosperity, and community advantages. These included: increased immunization coverage, initiatives to reduce school dropout rates, community-based nutrition promotion, and micronutrient supplementation.

Their conclusion? Micronutrients for people in poor countries. No, I don't think SIAI was considered as an option.