What do Baked Lay’s potato chips, Simply Tostitos chips and Diet Mountain Dew have in common? They’re all “guilt-free,” according to how PepsiCo categorizes them. In reporting higher global sales Wednesday, PepsiCo CEO Indra Nooyi reiterated that 45 percent of the company’s revenue now comes from such “guilt-free” products. The comment underscores how malleable claims about healthfulness can be, and how food makers are trying to position themselves. Even the Food and Drug Administration said last year that it is re-evaluating its guidelines for when companies can use the term “healthy” on packaging to reflect the latest science. For PepsiCo Inc., the definition of “guilt-free” is broad. Though PepsiCo Inc. doesn’t stamp its packages with the guilt-free label, the idea conveys the message of how they’re generally marketed. More