Grocers including Kroger and Safeway are jumping on the bandwagon of offering nutritional advice to customers. Many shops are using the NuVal system, which ranks foods based on their nutritional values. But some manufacturers disagree with the rankings, which can influence consumer purchases. Wal-Mart is set to launch a nutrition program this summer. Hy-Vee, Kroger and Wegmans have hired registered dietitians to help customers make food choices.