The ins and outs of prenatal supplements

Dietitian and pregnancy nutrition expert, Claudia Vavasour, from Fertility Nutrition, discusses the ins and outs of prenatal supplements and what your body and baby actually need.

One of the most common questions I’m asked in my practice as a fertility and prenatal dietitian, is around supplements. In particular, “Which supplements should I be taking in pregnancy, and are folic acid and iodine really enough?”.

Firstly, eating a healthy diet during pregnancy is important to ensure you're consuming an abundance of vitamins and minerals. But as your nutrient requirements soar, you may need to opt for nutrition supplements to fill any possible nutritional gaps for both you and your unborn baby.

Remember that as well as needing to get enough nutrients, you also need to be careful of exceeding your requirements. Everyone’s needs are different based upon their dietary intake, size, nutritional stores, physical activity, genetic history, medical history and lifestyle, so it’s best to speak to a dietitian about which nutrients you can meet through your diet, and which you may need to supplement.

To help guide you, here is a breakdown of the most common nutrition supplements that you may need during pregnancy. It’s important to remember that you should always seek advice from your midwife, doctor or dietitian before taking any supplements.

FOLATE NEEDS ARE HIGH IN PREGNANCY

Folate, put simply, is required for growth and development. It’s needed every time your cells divide. It’s an essential B vitamin that’s well established for it’s role in reducing the risk of neural tube defects (NTDs), the most common one being spina bifida. Not only is folate needed for preventing NTDs, but insufficient folate in pregnancy is associated with preterm birth, low birth weight, and poor foetal growth.

Folate is an umbrella term given to all the different forms, of which there are many. Folic acid and folate are often used interchangeably – in fact, there’s even a lot of confusion among professionals about the difference. Let me explain…

We measure folate in dietary folate equivalents (DFEs) because folate from food is less biologically active compared to synthetic folate such as folic acid, folinic acid, or methylated folate (50% versus 85%, respectively). Our needs for folate increase by approximately 30% in pregnancy, going from 400 to 600 micrograms per day of DFEs. Unfortunately data from nutrition surveys show that NZ women are coming up short on their folate intake. Supplementing with 400 micrograms (equivalent to 680 ug DFE) of folic acid/day is sufficient to reduce the risk for women who have no history of NTDs. However, only 800 micrograms and 5 miligram tablets of folic acid are currently available on prescription in NZ. Herein lies the confusion!

What about the other forms of folate I hear you say… Before hitting your bloodstream, your body converts folate into the biologically active form called methyl folate. However, there is very strong evidence demonstrating that 400 micrograms of folic acid per day is really effective at reducing NTDs. Research has shown that methyl folate increases blood folate just as effectively as folic acid, however, as it currently stands, we do not have enough evidence to confidently state that supplemental methyl folate alone will prevent neural tube defects. It is technically possible to obtain this much folate from food alone, but that would mean eating an awful lot of spinach and broccoli. And that can be really challenging, especially in the first trimester, when pregnancy symptoms leave us craving beige carbohydrates (despite best intentions)! If you or someone in your family has one of the following you may need higher doses of supplemental folate: (Speak to your healthcare professional for individually tailored advice.)

+  History of a NTD affected pregnancy

+  A family history of NTDs

+  Taking anticonvulsant drugs

+  High BMI

+  Coeliac disease

+  Inflammatory bowel disease

+  Insulin dependent diabetes

+  MTHFR gene defect

Concerns have been raised about the safety of higher doses of folic acid, due to the chronic build-up of unmetabolised folic acid. In the past, researchers have linked these high supplemental doses to increased cancer rates. However, to date, the research is reassuring and there is not yet a clear link between unmetabolised folic acid and adverse health outcomes. It makes sense to use methylated folate when choosing a high dose 5 mg supplement, to avoid the chronic build-up of unmetabolized folic acid and possible health implications.

Furthermore, it's estimated that 10% of the population have a MTHFR gene defect, whereby they have reduced capacity to convert folic acid into the methylated form, which hits the bloodstream. They will still be able to convert some folic acid, but higher doses more than 1 mg/day should be from methylated folate only.

To summarise, a minimum of 400 micrograms of folic acid is recommended for at least 1 month prior to pregnancy and throughout in addition to a folate-rich diet. Foods that are high in folate include dark leafy greens, broccoli, avocado, citrus, legumes, and nuts and seeds. If you require higher doses of folate for more than 3 months, or have a known MTHFR gene defect, methylated folate is the right choice for you, in addition to 400 micrograms Folic Acid/day.

IODINE

Iodine is essential for your baby’s brain and nervous system development. Iodine needs increase in pregnancy due to the marked change in thyroid function, which is responsible for the regulation of body temperature, blood cell production, metabolic rate, growth and muscle function. Women who have a thyroid condition should speak with their healthcare professional to ensure iodine is safe to take. But most women are recommended to take an iodine supplement containing 150 micrograms daily from 3 months pre-conception, during pregnancy and breastfeeding. Something you may not be aware of is that most pregnancy multivitamins already contain iodine, so you should always check the label and DO NOT take an iodine supplement in addition as this can interfere with your thyroid function and lead to toxicity.

CHOLINE

This B vitamin-like nutrient has gained more attention in recent years. It’s been found to be important for your foetus’s brain development and may also help prevent some common birth defects. Alarming research from Australia found that only 1% of women of reproductive age have an adequate intake of choline. Experts advise 440 mg choline is needed a day and getting enough dietary choline is really important because most prenatal vitamins do not contain choline.

The best sources of choline include eggs, beef, chicken, milk, soy products and peanuts, with 2 eggs providing you with 50% of your daily needs. Whilst our body can produce some choline on its own, it doesn’t make enough to meet all your needs while you’re pregnant. The availability of choline in plant-based food sources is limited, therefore, if you are following a plant-based diet or unable to meet your choline needs through diet alone, it may be beneficial to consider a choline supplement.

IRON

Iron is involved in growth and development and is needed to make haemoglobin; a protein that carries oxygen around your body. Demand for iron increases during pregnancy and insufficient intake or poor absorption of iron can result in iron deficiency and anaemia.

It is necessary during pregnancy to increase iron stores as your baby draws on these during the first 5-6 months after birth. Most women struggle to get enough iron in their diet, so it’s useful to have your ferritin (iron stores) tested throughout  your pregnancy to determine your need for supplements. Supplementing iron daily during your pregnancy reduces the risk of maternal iron deficiency and anaemia, as well as low birth weight. However taking supplements without the guidance of a healthcare professional isn’t recommended as they can cause side effects such as constipation, vomiting, and diarrhoea, and can interfere with absorption of other minerals such as zinc and calcium. Focus on eating iron-rich foods such as red meat, legumes, green leafy vegetables and wholegrains.

There are differing forms of iron supplements available. If you do have a deficiency, it’s essential you take the dose as recommended by your healthcare professional, in order to correct the deficiency. If you experience side effects, there are others forms of iron which are gentler on your tummy, but are not available on prescription (non-subsidised/over the counter). 

CALCIUM

Calcium is a mineral necessary for forming your foetus’s bones and teeth. It's important that you consume enough calcium to meet both your requirements, because the calcium demands of a foetus trump that of the mother. Insufficient dietary intake will result in a reduction of maternal bone mass, placing you at risk for osteoporosis later in life.

Recommended dietary intake of calcium is 1000 mg/day and it’s very achievable to meet your calcium requirements through your foods. The best sources are milk and other dairy products, such as cheese and yoghurt. For those who have difficulty digesting milk products, you can get calcium from other sources, such as broccoli, fortified foods (cereals, breads, and juices), almonds and sesame seeds, sardines or anchovies with the bones, and dark green leafy vegetables. But you may also like to discuss getting a calcium supplement from your healthcare professional. Here’s why…

Low calcium intake has been linked with pre-eclampsia and preterm birth. Those on a low or dairy-free diet (with calcium intakes <600mg/day), twin or triplet pregnancies, or with a history of high blood pressure or pre-eclampsia, may benefit from a calcium supplement. 

VITAMIN D

This ‘sunshine vitamin’, vitamin D, works alongside phosphate and calcium to help the foetus’s bones and teeth develop. It’s essential for healthy skin and eyesight and has been connected to reduced rates of eczema and preterm births.

During pregnancy, women at higher risk of becoming deficient in vitamin D are those who:

+  Have darker skin – this includes many women from Africa, the Indian subcontinent and the Middle East as well as some Māori and Pacific women.

+  Completely avoid sun exposure for religious, personal or medical reasons, for example, women who are covered by veils and clothing over the whole body because they have had skin cancer, skin damage from the sun or are on photosensitising medications.

+  Have liver or kidney disease, or are on certain medications (eg some anticonvulsants) that affect vitamin D levels.

+  Live in southern regions of New Zealand in winter (ie, south of Nelson-Marlborough) – they're more likely to be vitamin D deficient in late winter or early spring.

Women who are 'at higher risk' should be supplementing with 400 IU/day. But if levels are low (<50 nmol/mol), then a supplement plan should be tailored to the individual. The subsidised monthly 50,000 IU capsule prescribed in NZ is not recommended for pregnant women, due to a lack of evidence on its safety in pregnancy.

Pregnant women who are not 'at risk' may also benefit from a daily vitamin D supplement of between 400-600 IU throughout their pregnancy especially in the third trimester. Doses at this level are considered safe and are below the upper limit of 4000 IU/day. 

OMEGA 3s

Omega 3 fatty acids are important for babies' developing eyes, brain and nervous system. New research has found they may also lower your risk for pre-eclampsia, postnatal depression and preterm delivery. Omega 3 fatty acids are found naturally in many kinds of fish such as salmon, sardines, anchovies and tuna. Smaller amounts are found in flaxseeds, chia, hemp seeds, and walnuts. Whilst not everyone is a seafood lover (especially with food aversions in pregnancy), unfortunately seeds alone won’t give you enough omega 3 fats.

You should aim for 500 mg DHA/day (DHA stands for docosahexaenoic acid), you don’t need more than 1000 mg of DHA + EPA/day to help you have a full length pregnancy and for your baby to grow to a healthy weight in the womb. More won’t give you any additional benefit. Algae oil supplements are an alternative to fish oil supplements for vegetarians and vegans. Be sure to stop any omega 3 supplement by 36 weeks gestation and recommence post-partum.

For those of you who enjoy fish, eat at least two servings of fish or shellfish per week before getting pregnant, while pregnant, and while breastfeeding. Some types of fish have higher levels of mercury than others. Mercury is a metal that has been linked to birth defects. Do not eat Cardinal fish, Dogfish (excluding rig), Lake Rotomahana trout, Lake trout from geothermal regions, school shark (Greyboy, Tope), Marlin (striped), Southern bluefin tuna or Swordfish any more than one serve per fortnight. You can check the Ministry of Health website for up to date information on safe fish varieties to consume in pregnancy.

A WORD ON PROBIOTICS

Probiotics have been touted as beneficial for all sorts of medical conditions. Research has found certain strains of probiotics taken in pregnancy to be effective for reducing atopic eczema in infants and reducing severity of postnatal depression. A 2018 systematic review and meta-analysis found no evidence that taking probiotics during pregnancy either increased or decreased the risk of preterm birth or other infant and maternal adverse pregnancy outcomes – great news! However, in 2021 a Cochran review found that low quality evidence from 6 trials have not clearly identified the effect of probiotics on the risk of gestational diabetes. And alarmingly, high-quality evidence suggests that probiotics probably increase the risk of pre-eclampsia.

As it currently stands, there are eight SPRING ongoing studies that may help to clarify the role that probiotics play in pregnancy. I recommend you avoid self-supplementing with probiotics in pregnancy at this stage, particularly if you have a higher risk of developing pre-eclampsia, and that you seek advice from your healthcare provider.

PRENATAL

Folate is the only micronutrient that is recommended to be supplemented during pregnancy worldwide. However, as micronutrients are essential during pregnancy, taking a prenatal vitamin can often be beneficial.

Most women will just choose a pregnancy multivitamin based on marketing, or the advice of their friends or doctors. Unfortunately, most doctors typically recommend prenatal multivitamins based on marketing as well.

Only dietitians have the skills to individually tailor supplement prescriptions during pregnancy. When it comes to supplementation during pregnancy, it is important to remember that more does not always mean better. In fact, excessive amounts of some nutrients can be harmful to the developing baby.

Dr Lisa Houghton from the University of Otago's human nutrition department recommends that women who are taking a multivitamin supplement, choose one that contains folic acid, potassium iodate, and iron and should avoid one which exceeds 10,000 IU of Vitamin A from retinol/day. The American College of Obstetricians and Gyneacologists recommend to eat healthy foods and take a prenatal vitamin to supply you with all the vitamins and minerals that you need.

Unfortunately, there is no universal prenatal vitamin that is suitable for everyone, therefore, the gold standard recommendation is that a prenatal supplement regime should be personalised based upon a women’s nutrient needs, and modified throughout pregnancy as her needs change. What’s most important is that your prenatal  supplement contains 400 micrograms of folic acid, and, IF it contains iodine, do not consume an additional iodine supplement.

SUMMARY

It's important to remember that there is no one-size-fits-all approach for nutrition and supplementation. People have different diets, lifestyles, and medical history, therefore what works for your friends and colleagues may not necessarily work best for you. I hope this breakdown helps to inform your decision making process, and remember – before deciding what supplements to take, always seek advice from your healthcare professional.

Claudia Vavasour is a NZ registered dietitian and leading expert in fertility and pregnancy nutrition. Her practice, Fertility Nutrition, has a team of specialised registered dietitians who are dedicated to helping women and couples improve their fertility, have healthy pregnancies and give their babies the best start in life through evidence-based nutrition. Find her at fertilitynutrition.co.nz and on social media – Facebook @fertilitynutritionnz,   Instagram @fertility_nutrition_dietitians.