I’ve just learned about a organization called ISSN.
Here is their link.
Hope this helps.
The best course is the presicion nutrition course. The cours only opens up twice per year and is limited, but the program is second to none. Dr Berardi is the mastermind behind the program and also authored ISSA’s Fitness Nutrition Course which is a great course as well. If you are looking for just a CEC you should look at Nancy Clark, Berdot’ Advanced Nutrition, or Power Eating…cant remember who authored it. I believe all of these can be found on either DSW Fitness or Exercise Etc.
These are the two main places I go for my CEC’s
There’s nothing that’s really recognized by clients except for a degree or even more importantly a registered dietitian. That’s probably more than you want. I’ve found that if you know enough then they believe you. It would be a good idea to take a couple courses at your local university or community college. After that read, read, read. You can’t read too much about nutrition. Read things you do and don’t agree with.