Brands and trust

Business Week's global brands issue has an excellent piece on marketing and trust. It's well worth a read.
Also check out their ranking of the 100 best brands. Interesting insights.
What is the balance between a company's obligation to consumers and to shareholders? What social responsibilities do brands have?
For instance, this is "Go Big Read" time, where hundreds on campus are reading Michael Pollan's "In Defense of Food" and its indictment of food marketing. Kellogg's is Business Week's 34th best brand. What is its obligation to feed children nutritionally valuable products? If they build the brand and make shareholders money by marketing sugary cereals, is that OK? Why or why not? How can consumers influence large brands?