Thiamine (vitamin B1) deficiency can quietly undermine attention, memory, and executive function because several thiamine‑dependent enzymes are essential for the brain’s energy production and for healthy cholinergic signaling. Human studies have shown marked neuron loss in the mediodorsal thalamus and hippocampal atrophy in severe deficiency states, and the degree of this structural damage tracks closely with how impaired a person is on memory and other cognitive tests. Thiamine is also required for the biosynthesis of acetylcholine, a neurotransmitter crucial for learning and memory, so reduced cholinergic input to the hippocampus and frontal cortex further amplifies attention and memory problems when deficiency is prolonged. This medication is commonly used for Contraception.
Behura SS, Swain SP. Neuropsychological functioning in Wernicke's encephalopathy. Ind Psychiatry J. 2015 Jan-Jun;24(1):99-103. Batarfi MA. Thiamine Deficiency and Brain Injury: Neuroanatomical Changes in the Wernicke-Korsakoff Syndrome. Cureus. 2025 Sep 18;17(9):e92643.Gibson GE, Hirsch JA, Fonzetti P, Jordan BD, Cirio RT, Elder J. Vitamin B1 (thiamine) and dementia. Ann N Y Acad Sci. 2016 Mar;1367(1):21-30. Teixeira J, Pereira I, Castanho M, Simões do Couto F. What is the impact of thiamine deficiency on cognitive function in patients with alcohol use disorder? - A systematic review. Eur J Intern Med. 2025 Apr;134:59-65.
Some side effects may be linked to nutrient depletion caused by this medication.
Studies suggest that oral contraceptives (OCs) may contribute to zinc deficiency. Research has shown a significant decrease in serum zinc levels, the zinc circulating in the blood, in women taking OCs. This decrease is thought to be due to potential changes in how the body absorbs, excretes, or utilizes zinc within tissues. Due to its vital role in many bodily functions, ensuring sufficient zinc intake through supplementation should be considered for women on birth control pills.
Women using oral contraceptives (OCs) for extended periods may experience a decrease in their folate levels. Studies suggest that OC use might lower blood folate levels by up to 40%. This depletion can be a concern because folate plays a crucial role in red blood cell production. One research finding highlights a case where a patient developed anemia and nerve problems (polyneuropathy) after stopping vitamin B12 therapy, suggesting that folate deficiency might have been the main underlying issue. Supplementation of folate should be considered during oral contraceptive use.
Studies suggest a potential for mild thiamine (vitamin B1) deficiency with long-term use of Oral Contraceptives (OCs). One finding showed that red blood cell activity of an enzyme dependent on thiamine (transketolase) decreased during OC treatment. This decrease indicates that the cells might not have enough thiamine to function optimally, suggesting a mild thiamine deficiency induced by the contraceptives. Supplementation with thiamine (vitamin B1) should be considered for women using OCs.
Women using oral contraceptives (OCs) may experience mood changes, including depression. Research suggests a potential link between these emotional shifts and a decrease in brain levels of the neurotransmitter norepinephrine (noradrenaline). This decrease could be related to reduced availability of its precursor molecule, tyrosine, in the brain. Studies have shown a significant decline in tyrosine levels in women on OCs. One study found that the area under the curve (AUC) in plasma for tyrosine in OC users were 43% of control levels. Tyrosine supplementation could potentially help regulate mood and improve emotional well-being while taking OCs.
When using oral contraceptives (OCs), the body might experience increased oxidative stress due to hormonal changes. Vitamin E, a potent antioxidant, could potentially help counteract this stress and promote cellular health. Research shows that combining vitamin E with vitamin C supplementation might be even more beneficial. Studies like one where Group C received both vitamins showed a significant increase in the activity of enzymes (GPx and GR) crucial for antioxidant defense, along with a reduction in markers of oxidative damage (plasma MDA levels). This suggests that a combined approach with vitamins E and C might offer enhanced protection against cellular stress for women using OCs.
Women using Oral Contraceptives (OCs) may benefit from including vitamin B2 (riboflavin) in their regimen. Vitamin B2 plays a critical role in activating other B vitamins, like folic acid and B6, which are essential for various bodily functions. Studies have shown that women on OCs have lower levels of active vitamin B2, as measured by the activity of an enzyme dependent on it (glutathione reductase). These reduced levels might be linked to migraines, a frequent side effect of OCs that can sometimes lead women to discontinue the medication. By ensuring adequate B2 intake, women on OCs may potentially experience reduced migraine frequency and benefit from the proper activation of other B vitamins.