BH4 plays a critical role in both neurotransmitter and nitric oxide production. It can be depleted by the A1298C, DHFR, high ammonia levels (from CBS), oxidative stress, or a lack of SAMe or NADH. BH4 Assist contains Royal Jelly, which has a naturally occurring BH4. In addition, BH4 Assist contains folinic acid, (6S)-5-methyltetrahydrofolic acid, SAMe and lithium orotate to support the production of BH4.