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Do oral contraceptives really cause nutrient deficiencies?

What is Oral Contraceptive?

Oral contraceptive (OC), often referred to as just “the pill”, is a form of hormonal contraception and the most commonly used drug in developed countries [1]. According to the CDC, as of 2017, about 9.1 million women aged 15-49 in the US were currently using OC [6]. Oral contraception is most often a combination of estrogen and progestin hormones, which work together to prevent ovulation, thus, preventing pregnancy [1]. When first introduced, OCs contained a much higher hormone content than they do today [4]. Now, various forms of pills, referred to monophasic or triphasic, can contain varying amounts of hormones, depending on the brand and type of pill. Because of this, early studies drew dramatic conclusions about the effect of OC on women’s health, including severe nutrient deficiencies. As time goes on and technology advances, these studies have been revisited and reconducted for the general population of OC users today.

Does OC cause weight gain?

A popular misconception is that oral contraceptive leads to weight gain. A possible explanation for this could be the effect of OC on fluid retention [1]. OC has been noted to increase fluid retention which can cause swelling around body tissues and thus, weight gain [1]. However, a 2010 study found that OC use appears to cause a slight increase in the basal metabolic rate in female monkeys. Thus, leading to a decrease in body weight and body fat percentage in obese individuals [3]. These contradictory and limited findings suggest the complexity of weight management and the variability in individual response to OC.

How does OC affect vitamin and mineral absorption?

While earlier studies from the 1960s and 1970s found significant variance in the levels of essential vitamins and minerals in OC users, it’s important to once again note that these observations were found at a time where the hormone content of OC was much higher [4]. As well, many of these studies did not provide sufficient controls for confounding factors, and thus, are weak support for any conclusive result that OC may negatively affect various vitamin and mineral statuses [4]. Such a case is for folic acid, a synthetic form of folate, a water-soluble B-vitamin, important for enzymatic reactions including amino acid metabolism, DNA synthesis, cell division, and reducing the risk of neural tube defects [1].

What does more recent evidence have to say about OC and nutrient deficiencies?

More recent evidence suggests minor effects of OC on vitamin B2, B6, B12, and iron.

Vitamin B2, also known as riboflavin, is an essential water-soluble vitamin important for vital metabolic processes, energy production, and normal cell function and growth [1]. OC use has been found to aggravate the prevalence of B2 deficiency in women of child-bearing age and low socioeconomic status [1]. However, a recent study found that B2 supplementation in women taking OC has produced significant improvements in riboflavin status, particularly where dietary intake of B2 was insufficient [1].

Vitamin B6, another essential water-soluble vitamin is important for protein metabolism and the biosynthesis of neurotransmitters such as serotonin [1]. A recent large-scale US study found the concentration of a B6 compound, plasma PLP, was significantly reduced in 75% of women taking OC [2]. PLP concentration is inversely correlated with serum CRP, an inflammation indicator noted elevated in OC users [2], which further suggests that current low dose OC may have a negative impact on B6 status [4].

Vitamin B12, also known as cobalamin, is another essential water-soluble vitamin important for cell metabolism, DNA and fatty acid synthesis, as well as energy production [1]. Little to no difference was found in holo-TC concentration (one of the two binding proteins to which B12 is attached to) in association with OC use. This may account for some reports of low serum cobalamin concentrations in women using OC as holo-TC is the protein that is tested for to determine B12 status. Some studies have also shown that OC is associated with a significantly lower haptocorrin concentration (the other of the two binding proteins) [4]. The hormones in OC are believed to affect haptocorrin production as decreased levels of the protein are also observed during pregnancy, where hormone levels are variable as well [4]. Contradictory findings may be attributed to varying estrogen concentrations in different forms of the pill, compliance with OC use, and/or diet [4].

Aside from deficiencies, there are a few nutrients that have shown improvement with OC use, two of which include iron and vitamin D. Increased serum iron levels in women using OC may be associated with decreased menstrual blood flow, as excessive blood loss is a primary cause for iron deficiency [2]. Some studies also suggest that OC increases the level of vitamin D binding protein which may protect vitamin D from damage, thus increasing the amount of vitamin D present in the blood [6].

While OC may temporarily increase vitamin D concentration, stopping OC may worsen vitamin D deficiency and adversely affect pregnancy outcomes [5]. Thus, vitamin D levels should be carefully monitored in women discontinuing OC use, especially those seeking to get pregnant.


Based on these findings, extra attention should be paid to ensure women using OC obtain sufficient amounts of B2, B6, and B12 via both incorporating particular foods in one’s diet as well as through supplementation. Vitamin D levels should also be monitored in women coming off OC and seeking to get pregnant.

Much of the speculation surrounding OC and nutrient deficiencies are based on decades-old research that is in desperate need of reevaluation, especially to account for the significantly lower hormone content in today’s versions of the pill. However, according to current research, such deficiencies are proven to be minimal and can easily be resolved through diet and/or supplementation.

Written by Vanessa Ramasammy on behalf of Supriya Lal, RD


[1] Palmery M, Saraceno A, Vaiarelli A, Carlomagno G. Oral contraceptives and changes in nutritional requirements. Eur Rev Med Pharmacol Sci. 2013 Jul;17(13):1804-13. PMID: 23852908.

[2] Dante G, Vaiarelli A, Facchinetti F. Vitamin and mineral needs during the oral contraceptive therapy: a systematic review. Int J Reprod Contracept Obstet Gynecol 2014;3:1-10.

[3] Edelman, J.T. Jensen, M. Bulechowsky, J. Cameron, Combined oral contraceptives and body weight: do oral contraceptives cause weight gain? A primate model, Human Reproduction, Volume 26, Issue 2, February 2011, Pages 330–336,

[4] Stephanie Mc Wilson, Brittney N Bivins, Katelyn A Russell, Lynn B Bailey, Oral contraceptive use: impact on folate, vitamin B6, and vitamin B12 status, Nutrition Reviews, Volume 69, Issue 10, 1 October 2011, Pages 572–583,

[5] Callegari, E., Garland, S., Gorelik, A., Reavley, N., & Wark, J. (2017). Predictors and correlates of serum 25-hydroxyvitamin D concentrations in young women: Results from the Safe-D study. British Journal of Nutrition, 118(4), 263-272. doi:10.1017/S0007114517002021

[6] Daniels K, Abma JC. Current contraceptive status among women aged 15–49: United States, 2015–2017. NCHS Data Brief, no 327. Hyattsville, MD: National Center for Health Statistics. 2018.

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