In some adults, thiamine (vitamin B1) deficiency shows up first in the gut, with anorexia, nausea, early satiety, abdominal discomfort, constipation, or a sense that “the stomach and intestines just are not moving right.” Case reports and small series in humans describe improvement in nausea, constipation, dysphagia, and intestinal dysmotility after thiamine supplementation, which supports a causal role for deficiency in disordered gastrointestinal motor and secretory function. The practical takeaway is that, when patients have otherwise unexplained appetite loss and upper or lower GI symptoms in the setting of poor intake, alcohol use, or critical illness, it is important to consider and correct possible thiamine deficiency as part of the evaluation. This medication is commonly used for Contraception.
Prakash S. Gastrointestinal beriberi: a forme fruste of Wernicke's encephalopathy? BMJ Case Rep. 2018 Jul 6;2018:bcr2018224841. Duca J, Lum C. Rare Presentation of Thiamine Deficiency as Gastrointestinal Syndrome. Hawaii J Med Public Health. 2014 Sep;73(9 Suppl 1):46. PMCID: PMC4175961. Overton E, Emelyanova A, Bunik VI. Thiamine, gastrointestinal beriberi and acetylcholine signaling. Front Nutr. 2025 Apr 9;12:1541054. A. Meckley et al. Suspected Thiamine Deficiency Secondary to Chronic. HCA Healthcare Journal of Medicine (2024) 5:2 Gastrointestinal Illness: A Case Report.
Some side effects may be linked to nutrient depletion caused by this medication.
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 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.
Studies suggest that women using oral contraceptives might have lower levels of vitamin C within their white blood cells (leukocytes) and platelets. This depletion could be linked to reduced activity of antioxidant enzymes like glutathione peroxidase (GPx) and glutathione reductase (GR) in the blood. These enzymes play a role in protecting cells from damage. Research also shows that supplementing with vitamin C, alongside vitamin E, can significantly increase the activity of these antioxidant enzymes in women taking OCs. This suggests that vitamin C supplementation might be beneficial for women on birth control pills.
Research suggests that oral contraceptives (OCs) may play a role in vitamin B6 deficiency. A deficiency is concerning because vitamin B6 plays a crucial role in mood regulation and blood sugar control. Some women using OCs experience symptoms like depression and impaired glucose tolerance, which could potentially be linked to this vitamin B6 deficiency. Low vitamin B6 levels are independently associated with an increased risk of blood clots in both arteries and veins (venous and arterial thromboembolism, or TE). This association suggests that the B6 deficiency caused by OCs might partly explain the higher risk of TE observed in women using birth control pills. This highlights the importance of ensuring adequate vitamin B6 intake for women on OCs and therefore supplementation should be considered.
Research suggests a potential decrease in magnesium levels in women using Oral Contraceptives (OCs). Studies have shown that women taking OCs have significantly lower serum magnesium compared to those not using them. Interestingly, the type of pill or duration of use doesn't seem to influence the degree of magnesium depletion. The observed decrease in magnesium with OC use might be associated with an increased risk of blood clots. Supplementation with magnesium should be considered during oral contraceptives 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.
Oral contraceptives (OCs) have been linked to a decrease in Vitamin B12 levels. Studies have shown a significant reduction in serum B12, the vitamin circulating in the blood, in women taking OCs for extended periods. One US study found a 40% decrease in B12 levels after five years of OC use. This decrease is concerning because vitamin B12 plays a crucial role in converting a form of folate (N-methyltetrahydrofolic acid) into its active form (tetrahydrofolic acid). This active folate is essential for healthy red blood cell production and other bodily functions. Due to the vital role of vitamin B12, supplementation when using OCs long-term should be considered.