HOUSTON — Snack and soda makers that are often blamed for fueling the nation’s obesity rates also play a role in educating the dietitians who advise Americans on healthful eating.Frito-Lay, Kellogg, Coca-Cola and others are essentially teaching the teachers. Their workshops and online classes for dietitians are part of a behind-the-scenes effort to burnish the images of their snacks and drinks. The practice has raised ethical concerns among some who say it gives the food industry too much influence over dietitians, who take the classes to earn education credits to stay licensed. “It’s not education. It’s PR,” said Andy Bellatti, a Las Vegas-based dietitian who helped found Dietitians for Professional Integrity, a group of about a dozen dietitians who are calling for the practice to end. With two-thirds of Americans considered overweight or obese, the makers of processed foods have shouldered much of the blame for aggressively marketing sugary and salty products. Critics say companies use the classes, which are usually free and more convenient than other dietitian courses, to cast their products in a positive nutritional light. Companies also collect the contact information of dietitians to mail them samples or coupons, in some cases to distribute to patients. Food and beverage companies say their classes are intended to inject perspective into the public debate over nutrition. At the annual Food and Nutrition Conference and Expo, the industry offered several workshops for thousands of dietitians. In Houston last fall, Frito-Lay explained to dietitians how it removed transfats from its Lay’s potato chips and other snacks. The makers of high fructose corn syrup encouraged them to question a study that ties the prevalence of the sweetener to higher rates of type II diabetes. And the company famous for its Frosted Flakes cereal taught about the benefits of fiber. “Has anyone tried our new chickpea burgers?” asked an employee of Kellogg, which also makes Special K and MorningStar veggie burgers. Cost of educationCorporate influence isn’t limited to dietitians. In 1997, the Food and Drug Administration issued guidance intended to address concerns about the role of drugmakers in continuing medical education for doctors. The guidance drew distinctions between ads and education, essentially stating that drug companies shouldn’t influence the latter. Those barriers don’t exist between food companies and dietitians. The Academy of Nutrition and Dietetics, a Chicago-based professional group with more than 75,000 members, governs the path to becoming a registered dietitian and oversees the accreditation for continuing-education providers. Glenna McCollum, the academy’s president, said dietitians are trained to question any findings that might not seem sound. “Some of the information provided may need to be challenged,” she said. “That’s part of the job.” For registered dietitians, continuing education is a requirement, not an option. After earning a bachelor’s degree in nutrition, completing an internship program and taking an exam, they must earn 75 credits of continuing education every five years. An hourlong class typically translates to one credit. Education providers, which must pay a $250 application fee and a $300 annual maintenance fee thereafter, have to abide by certain standards. Classes must be based on relevant subjects and conducted by qualified personnel. But materials for individual classes are not pre-screened. Various organizations provide continuing education, including universities and professional groups. But the classes can be costly. The ones offered by food companies are usually online and free. A call for change Teaching dietitians isn’t a new practice in the food industry. General Mills, which makes Cheerios, Lucky Charms, Yoplait yogurt, Pillsbury dough and Progresso soup, has been an education provider through its Bell Institute of Health and Nutrition for at least 15 years. The practice came under scrutiny after a report last year by public health lawyer and vocal food industry critic Michele Simon detailed the industry’s deep ties to the field. Shortly afterward, a small group formed Dietitians for Professional Integrity to call for change. A petition by the group got more than 25,000 supporters on Change.org. The academy provided an audit to The Associated Press that said only 600 of those signatures were by its members. Others also question the practice. Bill Dietz, a former director of the division of nutrition and physical activity at the Centers for Disease Control and Prevention, noted that an online class by Coke titled Understanding Dietary Sugars and Health was taught by two instructors with industry ties. One disclosed ties to the Sugar Association and companies including the candy bar maker Mars. The other disclosed ties to the Corn Growers Association on the subject of high fructose corn syrup. At one point during the online class, one instructor said he doesn’t think there should be dietary guidelines on sugar intake. Dietz said that viewpoint conflicts with the positions of many reputable groups, including the American Heart Association, which recommends that women consume no more than 6 teaspoons daily and men consume no more than 9. When classes are approved, the assumption is that the content is essentially endorsed by the Academy of Nutrition and Dietetics, Dietz said. As such, he said, the academy should be responsible for ensuring balanced perspectives. Still, he said, that doesn’t mean companies should be banned from playing a role in education. “It’s hard to be black and white about this,” he said. Outside the classroomFor companies, the classes can be a chance to spotlight new products. During culinary demonstrations at the conference in Houston, Kellogg and PepsiCo showcased recipes incorporating their products. And the educational outreach to dietitians doesn’t end in the classroom. Frito-Lay, which is owned by PepsiCo, said more than 1,000 dietitians are signed up to receive “SnackSense,” a newsletter from its online resource for health professionals. A recent issue highlighted the moderate sodium levels of a new line of Tostitos and offered recipes using the chips. At the convention, the Frito-Lay booth displayed an ear of corn, a bottle of oil and a small bowl of salt in front of a bag of Fritos. The idea was to illustrate the simple ingredients used in its snacks. Nearby, a Frito-Lay employee explained to a packed class of dietitians during a 20-minute briefing how the company removed transfats from its chips over the years. “Another thing I like to remind people about is that not all our chips are that high in sodium,” she said, noting that bread is the No. 1 source of sodium for Americans. Later, she invited them to try the company’s new barbecue-flavored chips. Attendees earned a credit for sitting in on three such sessions.