After I was asked this question by a parent again earlier this week it prompted this post. As some background speech pathologists work with children as young as premature infants with feeding difficulties through to adults who are in their nineties and beyond! Eating and communication are two of the most basic skills we need as human beings and therefore cover the full age spectrum.
When considering how old is “old enough” to seek help I advise parents that as soon as you are concerned/unsure is the right time to seek help. There are lots of things we can do with even very young children in helping parents to know how to adapt their interactions to facilitate communication development. It is never too early to seek help and if there is nothing to be concerned about then your therapist will reassure you and provide you with information about what milestones your child should reach when.
Children learn to communicate with others from birth (probably even earlier!) so if you have any concerns seek help now.