Why yes they are! In fact, quite a few health plans cover this service. Check with your health insurance provider to see if you have coverage. Essentially, a dietitian is covered the same way it would be with your massage therapist or physio. Each health plan is different, so be sure to find out.
At the end of the day, it’s important to do your homework when selecting a dietitian. You want to make sure that you are finding the right fit for you. There are a variety of specializations out there. So, keep that in mind when you are looking for help with something specific, i.e. sports nutrition.