The Pill & Nutrient Depletion: How your vitamin levels can be impacted by Hormonal Contraception

Reviewed by Dr. Harriet Connell

It is no exaggeration to say that the oral contraceptive pill revolutionised life for women. Introduced in the UK on the NHS in 1961 the combined oral contraceptive (COC) was one of the most significant medical advances of the twentieth century and is now used by over 3.1 million women in the UK.¹ Besides preventing unwanted pregnancy the combined oral contraceptive pill (combining the hormones oestrogen and progesterone) can also help alleviate symptoms of certain conditions such as PMS, PMDD, PCOS and endometriosis. Other benefits include increasingly regular periods, easing period pain and a reduced risk of ovarian, colon and womb cancers.,² There have been well-documented health concerns linking it to a small increased risk of breast cancer, cervical cancer³ and blood clots⁴ and it is not recommended for all women where other forms of contraception may be more appropriate but the COC pill remains the most popular form of prescribed contraception in the UK and many women take it for years, even decades.⁵

Food for thought

No medication, however, is without side effects and the oral contraceptive pill is no exception. Eight out of 10 women report side effects (most commonly mood changes, weight gain, nausea and breast tenderness)⁶ and five out of 10 women stop taking it within 12 months.⁷ In recent years there have also been growing concerns linking some types of oral contraceptives to depression.⁸

One of the lesser known side effects however – but one which the World Health Organisation (WHO) acknowledge is one of ‘high clinical relevance’ and should ‘receive great attention’ – is that taking the COC pill can lead to the depletion of some essential vitamins and minerals.⁹,¹⁰

**How does the combined oral contraceptive pill deplete nutrients?**

The exogenous hormones in the combined oral contraceptive pill appear to interfere with how the body metabolises nutrients in a number of ways and due to a combination of factors including:

1. Accelerated metabolism of active nutrients. Evidence indicates that exogenous hormones like HRT and hormonal contraception accelerate the metabolic pathways that consume nutrients such as Vitamin C, leading to lower levels available for storage and use¹¹.

2. Impaired absorption through reduced capacity of transfer proteins. Vitamin B12, vital for DNA synthesis and energy metabolism, is likely depleted through mechanisms that involve reduced binding capacity of a protein essential for B12 absorption in the stomach

3. Reductions in co-enzymes responsible for forming active nutrient compounds. Vitamin B6 levels are reduced due to the induction of enzymes like tryptophan oxygenase, leading to decreased availability of B6.¹¹

4. Excretion of key micronutrients. Exogenous oestrogens can lead to sodium retention and fluid accumulation. The increased sodium retention can disrupt the balance of electrolytes such as magnesium and zinc, as these minerals are often excreted at higher rates to compensate for sodium accumulation.¹¹

5. The loss of certain nutrients can trigger cascading effects on others. Nutrients such as magnesium are essential for over 300 enzymes to function properly¹². Exogenous hormones like HRT can lower magnesium levels, potentially disrupting enzymatic processes, leading to deficiencies in other compounds. For example, vitamin B6 and magnesium are interdependent in several enzymatic reactions, meaning reductions in one can exacerbate deficiencies in the other.

Which vitamins and minerals are at risk of depletion?

Research shows the key nutrients at risk of depletion when using the combined oral contraceptive pill are folic acid, vitamins B2, B6, B12, C and E and the minerals magnesium, selenium and zinc.¹³¹⁴ These nutrients are important to both your general well-being and hormonal health and a lack of them can cause fatigue, brain fog and low mood.

B vitamins – these are water soluble vitamins, meaning they are not stored in the body and are lost through sweat and urine so need to be regularly ‘topped up’ through food and/or supplementation. Some of the B vitamins which appear to be at particular risk when taking the contraceptive pill include:

Vitamin B12 – a nutrient found in red meat, fish, liver, eggs and dairy products which is essential for nerve health, energy production and cell repair. Women taking the COC pill have been shown to have lower levels of B12 than women who did not take it.¹⁵ This is a vitamin which is found primarily in animal products and you may not be getting high enough amounts if you are on a plant-based diet so supplementation is generally recommended.

Vitamin B9 also known as folic acid or folate is found naturally in dark leafy greens and wholegrains like brown rice and quinoa. This is a nutrient that is essential in early pregnancy as low folate levels are linked to an increased risk of birth defects. Studies from the 1960s onwards show that the pill may impair folate metabolism and a meta-analysis of 17 studies from 2015¹⁶ showed a significant reduction in folate levels for women of reproductive age who were taking the COC. If you coming off the pill because you want to get pregnant it is recommended you take a prenatal supplement or one designed specifically for women taking combined hormonal contraception to ensure you are not deficient in folate.

Vitamin B2 also known as Riboflavin, found in eggs, milk and meat. This is a vitamin which many women of reproductive age already appear to be low in and a fall in vitamin B2 levels has been consistently associated with taking the COC pill (plus the longer you take it the worse this depletion can become).¹⁷

Vitamin B6 also known as Pyridoxine, is found in beef, tuna, salmon, poultry, chickpeas, cereals and vegetables. Studies have shown that women on the combined contraceptive pill have significantly depleted levels of B6 with one US study revealing that three quarters of women taking it had significantly reduced levels.¹⁸ In a large cross sectional study researchers have also found that inadequate amounts of vitamin B6 were related to an increased risk of depression and anxiety in women.¹⁹ Significantly, these are often reported side effects of women taking the COC.

Vitamin C – another water-soluble vitamin this nutrient is known for its immune boosting benefits, it also has antioxidant properties and is necessary for collagen synthesis and healthy skin and gums. There have been some noted discrepancies between the vitamin C status of women on the COC and women who don’t take it but deficiency of vitamin C is rare and any shortfall is usually rectified by eating enough vitamin C-rich fruit and veg such as citrus fruits, peppers and green leafy vegetables like spinach and watercress.

Vitamin E – a fat soluble vitamin found in sunflower seeds, nuts, some vegetable oils and dark green leafy vegetables. It is also an antioxidant which helps protect cells from oxidative stress and is important for skin, immune health and heart health.

Magnesium – research shows levels of this mineral (essential for healthy muscles, bone health, heart health and improving mood and sleep) can be reduced by taking the COC pill. Researchers also suggest that the increased risk of blood clots could, in part, be related to these changes in magnesium status (magnesium depletion alters the magnesium/calcium ratio in the body leading to an increased risk of thrombosis or blood clots).²⁰ Levels of magnesium can also be depleted by stress and high intensity exercise so it is important to consider supplementing with additional magnesium.

Dietary sources of magnesium include bananas; green leafy vegetables such as broccoli, cabbage and spinach; nuts and seeds; pulses and seafood.

Zinc – this is a mineral which is key to immunity and fertility health. Studies have shown those who take the contraceptive pill have lower levels of it in their blood because they do not appear to absorb it as effectively. Hence an increased need to keep your zinc blood levels topped up through food or a supplement containing it.

Dietary sources of zinc include shellfish (oyster are particularly high in zinc but few of us eat them on a regular basis); meat; pulses; nuts and seeds; eggs and wholegrains such as quinoa.

Selenium – this mineral is important for immunity, thyroid function and also for helping antioxidants (substances which help to ‘mop up’ free radicals which can cause damage to cells and DNA). Low levels of selenium are already a growing problem in the UK due to low levels of it in the soil and over half of females over 11 are already getting below the recommended levels. Evidence also shows taking the pill can interfere with selenium absorption making women even more potentially at risk of low levels or potential deficiency.²¹

Dietary sources of selenium include Brazil nuts; fish and shellfish; beef, pork and poultry.

**Nutrients that can increase when taking hormonal contraception**

Conversely, research shows that some vitamins and minerals can be increased by taking oral contraceptives so you should avoid taking any additional supplements (either singly or as part of a multivitamin and mineral).

It is well documented that levels of the trace mineral copper are elevated in women who use combined oral contraception.²²,²³ These raised levels are usually not considered toxic but some research suggests it could lead to damage to cells and tissues – resulting in oxidative stress in the body. Serum copper levels usually return to normal after around four to six weeks of stopping COCs.

Getting the nutrients you need

The research (much of which has been around for decades) clearly shows that taking the combined oral contraceptive pill has the potential to deplete, or lead to an imbalance of many essential nutrients. How can you optimise your nutrient levels when taking, or coming off it (a particular concern if you are hoping to become pregnant)?

Diet. You can adapt your diet to compensate - eating a healthy, balanced diet which includes a range of the key dietary sources mentioned above – such as the Mediterranean diet. This should help to secure the nutrients you need for general health and to support healthy hormone regulation.

Supplements. For many reasons, sometimes we just don’t eat as well as we should and this is where taking a multi vitamin supplement, especially one formulated specifically to target hormo-nutrient health for women using hormonal contraception can usefully support any nutritional gaps. Significantly too, by addressing any nutrient depletions with a multivitamin and mineral supplement you could also reduce some of the side effects of taking the pill. In one randomised, placebo-controlled trial women given a dietary supplement that provided them with more than 100% of the recommended daily allowances (RDA) of nutrients reported a 58% improvement in their mood, an 80% improvement in nausea (a common side effect of COC use) and 64% said they were more likely to go on taking it.²⁴ The report concluded: ‘Since women who take oral contraceptives do not always have an adequate diet, may have an unhealthy lifestyle or may suffer from pathologies of malabsorption, the possibility to prevent vitamin and mineral deficiencies by taking appropriate dietary supplements should be considered a first-line approach by clinicians.’

Improving gut microbiome. Including regular amounts of prebiotic foods (such as onions, garlic, leeks and Jerusalem artichokes) and probiotic ones (live yogurt, kefir, miso, fermented vegetables like sauerkraut etc) in your diet or taking a probiotic supplement can also help to encourage a flourishing gut microbiome which should help your body to absorb the vitamins and minerals and minerals it needs from the food you eat.

Nutrient testing. If you want reassurance that you do not have a vitamin or mineral deficiency a blood test can diagnose this. There are tests which can be done at home using a finger prick blood sample or you can visit your GP and ask for one. Low levels of B12 or folate are particularly concerning and need to be diagnosed and treated as soon as possible for although most symptoms improve with treatment, some problems caused by deficiency cannot be reversed.²⁵