Ask the Pharmacist
“I’ve been on birth control for years and keep seeing posts saying it drains your vitamins. Is that true? Should I be taking something?”
This is one of the questions we hear most often at the counter, and it’s a good one. Birth control nutrient depletion is a real, well-studied drug-nutrient interaction, and that makes it squarely pharmacist territory.
The short answer: yes, hormonal contraception can shift the levels of certain nutrients. But the evidence is stronger for some than others, a lower number on a lab report doesn’t always mean a true deficiency, and a few nutrients actually go up. Here’s what we want you to know.
Birth control and nutrient depletion: a note on the research
Most studies on birth control nutrient depletion looked at combined oral contraceptives, the pills containing both an estrogen and a progestin. Many of them are also decades old and involved higher-dose formulations than most people take today. We know much less about progestin-only pills, the patch, the ring, or hormonal IUDs.
Estrogen is thought to drive many of these changes. It affects how the liver makes certain proteins, including the carrier proteins that transport vitamins and minerals in the blood. That matters, because it means some “low” lab values reflect a change in how a nutrient is carried, not necessarily a shortage in the body’s tissues.
Birth control nutrient depletion, ranked by strength of evidence
Vitamin B6: consistent evidence
B6 is the most consistently reported change. In a large analysis of U.S. national survey data, about three in four women using oral contraceptives who weren’t taking B6 supplements had blood levels below the adequacy cutoff. B6 supports neurotransmitter production, energy metabolism, and homocysteine regulation.
What we don’t know yet is how often this translates into symptoms. Mood changes are commonly linked to low B6, but the connection in pill users hasn’t been firmly established.
Folate: moderate evidence, highest stakes
Studies have found lower folate levels in pill users, though results vary. Why this one gets our attention: if you stop the pill to conceive, you want folate status to be solid before pregnancy, since folate is essential for early neural tube development, which happens before many people know they’re pregnant.
The U.S. Preventive Services Task Force recommends 400 to 800 mcg of folic acid daily for anyone who could become pregnant, pill or not. Some contraceptive brands now include a form of folate for exactly this reason.
Vitamin B12: lower on paper, less clear in practice
Serum B12 often reads lower in pill users. However, research suggests this largely reflects changes in the proteins that carry B12 in the blood, rather than true tissue deficiency. Functional markers like methylmalonic acid (MMA) are often normal.
This is a great example of why context matters when reading labs. That said, B12 is worth a closer look if you also follow a vegan or vegetarian diet, take acid-reducing medications or metformin, or have digestive conditions affecting absorption.
Magnesium and zinc: mixed evidence
Some studies report lower magnesium and zinc levels in pill users; others don’t. Both minerals are also tricky to measure accurately. Serum magnesium reflects only a tiny fraction of the body’s stores, and plasma zinc shifts with time of day, recent meals, and inflammation.
Interestingly, copper tends to rise with estrogen use, which can shift the zinc-to-copper balance.
Riboflavin, vitamin C, vitamin E, and selenium: limited evidence
These show up on many “nutrients depleted by birth control” lists, but the supporting research is older, smaller, and inconsistent. We don’t consider them a reason on their own to start supplementing.
Vitamin D: not depleted (and here’s the twist)
Estrogen-containing contraception is associated with higher vitamin D levels, roughly 20% higher in one large study, likely because estrogen raises vitamin D binding protein. Levels may drop after stopping. That’s worth knowing if you’re coming off the pill to try to conceive, especially here in Maine, where low vitamin D is already common through the long winter months.
Iron: often improves
Because the pill typically makes periods lighter, iron status often gets better, not worse.
A quick note on the shot
The injectable contraceptive (Depo-Provera) carries an FDA boxed warning about bone mineral density loss with long-term use. If you use it, calcium and vitamin D intake deserve a conversation with your provider.
At a glance
| Nutrient | Evidence | What it means |
|---|---|---|
| Vitamin B6 | Consistent | Most reliable change reported |
| Folate | Moderate | Most important if planning pregnancy |
| Vitamin B12 | Mixed | May reflect carrier proteins, not true deficiency |
| Magnesium, Zinc | Mixed | Hard to measure accurately |
| B2, C, E, Selenium | Limited | Not a strong reason to supplement alone |
| Vitamin D | Increases | Levels may drop after stopping |
| Iron | Often improves | Lighter periods mean less loss |
When does testing for nutrient depletion make sense?
We don’t recommend testing everyone on the pill. We do think it’s worth considering if:
- You’re planning to stop the pill to conceive. This is the best time to check folate, B12, vitamin D, and iron.
- You’ve been on hormonal contraception long term and have symptoms like fatigue, low mood, or poor energy that haven’t been explained.
- You have other risk factors, such as a plant-based diet, digestive conditions, heavy alcohol use, or other medications that affect nutrient absorption.
A few testing tips we share with patients:
- Tell whoever orders or reads your labs that you’re on the pill. Some reference ranges don’t account for contraceptive use.
- For B12, a serum level alone can mislead. Adding MMA or homocysteine gives a clearer picture.
- Homocysteine is a useful functional marker that reflects B6, B12, and folate working together.
- For B6, plasma PLP (the active form) is the standard test.
Test first, then supplement
When it comes to birth control nutrient depletion, it can be tempting to grab a ‘birth control support’ supplement and call it done. Our approach is to test first, then supplement. Targeted support based on your actual levels is more effective, avoids unnecessary products, and helps you avoid taking too much of any one nutrient. More isn’t always better, and B6 is a good example: long-term high doses have been linked to nerve problems.
For many people, a quality B-complex or a food-first approach covers the bases. For others, labs point to something more specific.
One important note: nothing here is a reason to stop or change your birth control. That’s a conversation for you and your prescriber.
How we can help
Our pharmacists can review your medications, check for birth control nutrient depletion and other interactions, and help you decide whether testing makes sense. We don’t diagnose or prescribe; we work alongside your primary provider to give you clear, evidence-based guidance. Consultations are available in person at 29 Marginal Way in Portland or via telehealth.
Stop by the pharmacy or book a consult to talk it through with us.
References
- Palmery M, Saraceno A, Vaiarelli A, Carlomagno G. Oral contraceptives and changes in nutritional requirements. Eur Rev Med Pharmacol Sci. 2013;17(13):1804-1813.
- Morris MS, Picciano MF, Jacques PF, Selhub J. Plasma pyridoxal 5′-phosphate in the US population: the National Health and Nutrition Examination Survey, 2003-2004. Am J Clin Nutr. 2008;87(5):1446-1454.
- McArthur JO, Tang H, Petocz P, Samman S. Biological variability and impact of oral contraceptives on vitamins B6, B12 and folate status in women of reproductive age. Nutrients. 2013;5(9):3634-3645.
- Sütterlin MW, Bussen SS, Rieger L, Dietl J, Steck T. Serum folate and vitamin B12 levels in women using modern oral contraceptives containing 20 µg ethinyl estradiol. Eur J Obstet Gynecol Reprod Biol. 2003;107(1):57-61.
- Harmon QE, Umbach DM, Baird DD. Use of estrogen-containing contraception is associated with increased concentrations of 25-hydroxy vitamin D. J Clin Endocrinol Metab. 2016;101(9):3370-3377.
- US Preventive Services Task Force. Folic acid supplementation to prevent neural tube defects: US Preventive Services Task Force reaffirmation recommendation statement. JAMA. 2023;330(5):454-459.
- Depo-Provera CI (medroxyprogesterone acetate) prescribing information, boxed warning: loss of bone mineral density. Pfizer.