National Health Services of Mexico (SENASICA) has guidelines on what is allowed, regulated and prohibited to bring across the border. The following is an overview of some of those items. Detailed information can be found on the SENASICA website.
Allowed imports may be brought in quantities for personal consumption if they are no risk of introducing a pest or disease. They are subject to inspection.
Regulated imports may be brought into Mexico according to their origin and manufacturing process and they have fulfilled the importation requirements.
Prohibited imports are those at risk of introducing a pest or disease into Mexico and under no circumstances can be imported.
The above information is courtesy of SENASICA.