Upvote:17
On arrival in the EU, be sure you comply with the regulations for bringing food into France. In particular, it seems that you are required to have a plant health certificate from the country of the nuts' origin. There are also additional regulations to comply with if you are bringing betel leaves in addition to the nuts. If in doubt, bring the nuts for inspection through the red ("goods to declare") channel when you arrive for confirmation that you have complied with the regulations.
However, it is illegal to bring betel into Saudi Arabia. It is not quite clear if this prohibition also applies to goods merely in transit, but I would very much advise against taking the risk. Better to avoid the chance of breaking the laws of such a strict regime if at all possible.