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There is a 26 step process for determining whether an export license is required. It can be found here: http://www.access.gpo.gov/bis/ear/pdf/732.pdf
My general review of these and other regulations indicates that most likely you will not require an export license for shipping dietary supplements to Ghana. However, it would be best to get an export import lawyer's second opinion or for you to follow the steps stated based on your detailed knowledge of what you are shipping and arrive at an independent decision.
You may find a lawyer in your area to assist you by going to http://www.lawyers.com/ or http://www.martindale.com/
See also this link above.