Evidence Level
Vitamin B6 (Pyridoxine) is well-documented for its role in addressing morning sickness during pregnancy. The American College of Obstetricians and Gynecologists (ACOG) recommends pyridoxine at doses of 10-25 mg three times daily as a first-line treatment, supported by the FDA-approved combination drug Diclegis (doxylamine/pyridoxine), which has been validated in multiple randomized controlled trials (RCTs). For premenstrual syndrome (PMS), Wyatt et al. (1999) conducted a systematic review of nine RCTs involving 940 participants, demonstrating that B6 at doses of 50-100 mg/day significantly improved overall PMS symptoms and depressive symptoms compared to placebo (OR=2.32 for overall symptoms and OR=1.69 for depressive symptoms).
In the realm of neurology, Hvas et al. (2004) found that B6 supplementation improved mood in individuals with marginal B6 deficiency. However, chronic high doses exceeding 200 mg/day have been associated with neuropathy, leading to the establishment of a tolerable upper intake level (UL) of 100 mg/day for adults.
Research into other potential benefits and risks includes studies on sleep and dreaming, cognitive function, and cardiovascular health. Adventure-Heart et al. (2018) reported that 240 mg of B6 increased dream recall in a randomized, double-blind, placebo-controlled study of 100 participants, though it did not affect sleep quality or dream vividness. Malouf and Grimley Evans (2003) conducted a systematic review of 109 trials, finding mixed effects on cognition in healthy older adults but no evidence linking B6 to cognitive impairment or dementia. Aybak et al. (1995) explored the impact of pyridoxine on blood pressure in hypertensive patients, while Sermet et al. (1995) examined its effects on platelet sensitivity.
Overall, Vitamin B6 is a versatile nutrient with established benefits for pregnancy-related nausea and PMS, though caution is advised regarding high doses to prevent neuropathy.