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How to choose the best prenatal supplement for you

As a fertility & pregnancy dietitian & nutritionist I am a huge advocate for a food-first approach. However, I also highly recommend a prenatal supplement before and during pregnancy to optimise nutrient stores and meet requirements, to ensure the healthiest pregnancy possible.

It's recommended that the right prenatal supplement be started on atleast 3-6 months prior to conception so if you haven't already begun, now is the time to start!

Many women struggle to know which is the best supplement for them, and rightly so with a market flooded with options! So I thought I would break it down and highlight the key things for you to look for when choosing your prenatal supplement.


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(1) Folate/Folic Acid

Folic acid is the synthetic form of the B-vitamin folate which is essential in the first 12 weeks of pregnancy as your baby develops its neural tube. This process can be occurring before you even find out that you’re pregnant!

Supplementing with folic acid and fortification of some of our breads and cereals with folic acid has been associated with a reduction in the rates of neural tube defects in babies (e.g. spina bifida). (PMCID: PMC3257747)

You may have heard about another form of folate as well, L-methylfolate or follinic acid. These are active forms of folate and are necessary in people who have the MTHFR gene mutation which results in a reduced ability to activate folic acid.

Testing for this genetic mutation isn't widely done, but you may want to err on the side of caution and opt for a supplement that contains both forms of folate just incase.

It's also important to know that you may have different folate requirements if you have a family history of neural tube defects, have type 1 or type 2 diabetes, inflammatory bowel disease or have a high BMI. You can talk to a dietitian more about these specific situations for more personalised advice.

(2) Iodine

Iodine is a key mineral before and during pregnancy, and is commonly routinely prescribed to pregnant women, including in New Zealand. Iodine is responsible for preventing a severe condition called cretinism in your baby which results in a marked reduction in mental capacity as well as some physical abnormalities. Low iodine intake during pregnancy has also been associated with reduced IQ and academic ability in children. (PMCID: PMC6804415)

Your prenatal supplement should have at least 150 mcg (micrograms), ideally, it should contain 220 mcg. Iodine is also found in seafood, seaweed, fish and in iodised salt. A basic starting point is to make sure your household is using only iodised salt, and including fish in your diet 2-3 times each week on top of iodine supplementation.

(3) Vitamin D3

Vitamin D3 (or activated vitamin D) is important for your hormone and immune function, cell division, absorption of calcium, and bone health (for both you and your baby!). Research has shown that poor vitamin D status has been associated with pre-eclampsia (high blood pressure) and increased risk of preterm labour as well as gestational diabetes. (PMCID: PMC6832549)

One of the best ways to get enough vitamin D is through sun exposure in short, regular periods. This can be easy in summer, but when winter hits in New Zealand it can be hard to get outside let alone into the sun! This is where a supplement becomes important.

When looking at forms of vitamin D on your supplements, there are usually two different kinds.The vegetarian form is ergocalciferol and the animal-based form is known as cholecalciferol, which could be important to consider if you're vegetarian or vegan.

Before you add vitamin D to your supplement regimen, get your blood levels checked with your doctor and discuss what might be the right dose for you. Many prenatal supplements contain some vitamin D, but usually this isn't enough to meet our requirements so additional prescribed vitamin D may be helpful.

(4) Omega-3 DHA

Omega-3 fatty acids are critical in maintaining a healthy pregnancy, and have been shown to increase your chances of conceiving too! DHA is the most important player when it comes to choosing your omega-3, as this is the compound associated with most benefits.

Pregnant women with a good omega-3 status have shown a 10x lower risk of going into early labour. Omega-3 status has also been linked with healthier, higher birth weight babies compared to those who had more omega-6 fatty acids in their diet and an imbalanced omega 3:6 ratio.

I recommend choosing an omega-3 supplement that provides atleast 1000mg of EPA + DHA combined (with atleast 200mg of that coming from DHA). Most prenatal supplements won't contain this amount so this is something that you may need to be taking separately.

If you don't eat fish, then supplementation is even more important. If you do eat fish, then aim to include this in your diet atleast 2-3 times each week to boost omega-3 intake even further.

(5) Vitamin B12

Vitamin B12 is found in any animal-based product or by-product (e.g. dairy & eggs). B12 is important for our nervous system and also plays an important role in the metabolism of folate which is important during pregnancy.

B12 helps with the formation of DNA and red blood cells and helps with brain and nervous system function too. When checking your prenatal supplement, looks for one that contains vitamin B12 (cobalamin), especially one with activated B12 (methylcobalamin). Some people need more B12 than others- so if you are taking metformin or acid-supressing medications for managing reflux, then B12 might be particularly important. You can have your B12 levels tested with your doctor and speak to them or your dietitian about supplementation if you are taking other medications.

(6) Iron

Iron is a key nutrient during pregnancy, both for baby's growth and development and for your health. Usually we see iron levels dip in the second and third trimester as blood volume increases rapidly to support your growing baby. Your iron requirements are almost double during pregnancy compared to pre-pregnancy. If you are vegetarian or avoid red meat then you may need additional iron to meet your needs. It is wise to get your iron levels checked before conceiving to ensure that you top-up your stores to avoid fatigue and iron-deficiency anaemia in the first and second trimester.

Adequate iron levels are not only important for pregnancy, but have also been shown as important for fertility too. Women who take iron supplements and eat iron from some dietary sources have been shown to have a lower risk of ovulatory infertility (PMID: 17077236). Some animal studies have also shown a reduction in the ability to conceive when iron deficient.

However, blanket supplementation or iron when trying to conceive and during pregnancy isn't necessarily the best approach. Some women struggle with constipation from iron supplementation, in which case looking for iron as amino acid chelate or ferrous glycinate could reduce the impact on your bowels. Too much iron isn't necessarily a good thing either and has been linked to a higher risk of gestational diabetes in pregnancy. It is therefore important that your iron supplementation advice is tailored to your specific needs.

It can be best to take your iron supplement at a different time of day compared to your prenatal supplement, as iron can be inhibited by other nutrients commonly found in prenatals like zinc and calcium.

(7) Choline

Choline is almost as important/ just as important as folic acid! It's responsible for baby's neural tube development and brain development so is important during the early stages of pregnancy. It's found commonly in eggs, meat, legumes, beans and mushrooms. Your daily requirement during pregnancy is ~440mg/day which can increase as your pregnancy progresses. 1 egg can provide around 150mg/day, which shows just how great a source of choline eggs are! If you don't eat eggs then a supplement would definitely be important for you to consider.

(8) Niacin (Vitamin B3)

Niacin (also known as vitamin B3 and listed on supplements as nictoinamide or nicotinic acid) is important for foetal brain development and has been shown to help in reducing the risk of miscarriage in the first trimester. There is also some research that it could help with digestion and reduce nausea- bonus!

Look for a prenatal that contains about 18mg of niacin as this is your requirement during pregnancy. If your supplement doesn't contain this, then consider switching if you have a history of miscarriage as niacin is particularly important for this. Otherwise, focus on boosting your niacin intake through diet. Foods rich in niacin include sunflower seeds, chia seeds, tuna, poulty, and beans.

(9) Other Nutrients:

Some other nutrients that you may like to look out for in your prenatal vitamin, include: selenium, vitamin K, magnesium and calcium. These ones aren't necessary for everyone, and usually we recommend them on a case by case basis depending on your intake, pregnancy and fertility history, and symptoms. Calcium requirements don't increase in pregnancy but adequate intake is important to maintain bone health, and has been linked with a reduced risk of developing gestational diabetes (PMCID: PMC5645148). Your requirement of calcium is 1000mg/ day. To put this into perspective; 1 glass of milk contains around 300-320mg of calcium. Most prenatal supplements don't contain alot of calcium so make sure to focus on consuming enough calcium from dairy products, fish with bones, and fortified soy products to meet your requirements.

Please note: This blog is for general information purposes only and does not replace individualised advice provided to you by your doctor or dietitian.

Book your express supplement consultation today and save 45%!

Get expert advice from a fertility and prenatal dietitian & nutritionist to tailor your regime to you in just 30 minutes, use THIS EXCLUSIVE LINK to book now and save 45%!


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