Choosing a prenatal supplement.
Choosing a prenatal supplement can be quite overwhelming! There are so many to choose from and they are all quite different. Some lack important nutrients, others don't provide sufficient amounts of nutrients, some are very large and difficult to swallow (tricky for those with morning sickness) and many contain synthetic versions of nutrients which your body may struggle to absorb or utilise.
As a wholefoods dietitian, I first and foremost recommend getting your nutrients from food. This is what my book, Nurture the Seed focusses on. Your body absorbs and utilises nutrients best when they come from food. In saying this, I appreciate that for many reasons (food aversions, nausea, food availability, socioeconomic factors, lack of energy etc), it can be difficult to meet the increased nutritional needs during pregnancy. In this case, supplements can be extremely helpful and may play a crucial role in the health of you and your baby.
So let’s see what you should consider when choosing a prenatal.
Notes:
- This article does not provide individual advice. If you would like a supplement plan that is tailored to your specific needs, you can book a Prenatal Supplement Package or book a 1:1 consultation with me in clinic.
- High quality evidenced-based research is lacking in regards to prenatal supplements. It is unethical to conduct such studies so we may never have the answer as to which supplements are “best”.
- More information on wholefoods, supplements and nutritional needs during pregnancy can be found in our book, Nurture the Seed.
What to look for in a prenatal multivitamin supplement
There are many things to consider when it comes to choosing a prenatal supplement. Below is a basic guide to some nutrients.
Iron
Synthetic iron is poorly absorbed and often causes gastrointestinal (GI) issues like constipation and nausea (most noticeable in doses of >50 mcg)
Iron bisglycinate (ferrous bisglycinate chelate or iron (II) glycinate) is generally better absorbed and more gentle on the GI system
Ferrous fumarate or ferrous sulphate tend to worsen GI symptoms and are not as well absorbed (you may like to avoid this form in your prenatal)
If your body doesn't tolerate synthetic iron well (especially in the first trimester), you may want to opt for a prenatal that doesn't contain any iron, and focus on eating iron rich foods. If an iron deficiency is identified, it’s likely that you will need a therapeutic dose of iron which will be taken separately to your prenatal (prescribed by your doctor or dietitian).
Note: As per the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG), iron supplementation is not routinely recommended for every pregnancy. That being said, iron needs are 1.5 times higher in pregnancy and the majority of women I see in clinic have low iron stores.
Folate
There should be 500 mcg of folic acid or activated folate (methylated folate or folinic acid) in your prenatal
Folic acid needs to be converted into methylfolate to be utilised by your body
Some women struggle to convert all of the folic acid into useable folate due to a common gene variant (the MTHFR-gene)
Activated forms of folate are easier for your body to metabolise, however they are more expensive. They may be listed as: L-methylfolate, L-5-methyltetrahydrofolate, L-5-MTHF, Levomefolate or folinic acid.
Note: There is a lot of controversy surrounding folic acid and bioactive forms of folate (methylfolate or folinic acid). Unfortunately we do not have the research (due to ethical reasons) to compare these two forms of synthetic folate and their effects on neural tube defects (NTDs). Folic acid is the only form that is proven to prevent NTDs, however methylfolate may be a better alternative as it is already a few steps ahead of folic acid in folate metabolism (in other words, it is a metabolically active form of folate). Consult your doctor or dietitian for individual advice on the best form of folate for you.
Iodine
Dietary sources of iodine are scarce, especially if you don't eat seafood or seaweed
Therefore it is recommended that your prenatal has at least 150 mcg (this is the recommendation from RANZCOG)
Women with thyroid conditions may need more or less iodine depending on their issue, so make sure you get individual advice if you fall into this category.
Vitamin D
As a guide, 1000 IU of vitamin D is helpful in a prenatal multivitamin to maintain your vitamin D status in pregnancy (please note this will depend on the season and how much sun exposure you get)
If you have low vitamin D stores, it is unlikely that a prenatal multivitamin will provide you with a high enough dose to correct a deficiency. In this case, you will need to take an additional vitamin D supplement. Your dose will depend on how deficient you are and in what time frame you need to correct it. Consult your dietitian or doctor for further advice.
Vitamin B12
An activated form is easier for your body to metabolise, however if you regularly eat animal products then it is unlikely to be of concern as most omnivores can reach their vitamin B12 intake from food
Activated forms - methylcobalamin or adenosylcobalamin (coenzyme B12, cobamamide and dibencozide)
If you are vegan or you have a known vitamin B12 deficiency, you will need a prenatal with a higher dose of vitamin B12 (or you may need a seperate supplement or vitamin B12 injections).
Note: If you take metformin, it is recommended you get your vitamin B12 levels checked with your doctor, as metformin can cause serum vitamin B12 deficiency (Kim et al 2019).
Long chain omega-3 fats (DHA + EPA)
If you don't eat oily fish (salmon, mackerel, sardines) or oysters 2-3 times/week, you will need to supplement your diet with long chain omega-3 fats known as DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid)
Not many prenatal supplements contain DHA and EPA, as they are 'bulky' which means they are difficult to fit into a capsule. Prenatals that do contain DHA/EPA are often large or the dose is quite small.
It may be easier to supplement with DHA/EPA separately to your prenatal (if you need to). 300 - 500 mg is suitable for pregnancy, more than this may be indicated preconception or postpartum.
The most common form of supplement is fish oil. For a vegan friendly option, opt for algae oil.
Choline
Choline is also a ‘bulky’ nutrient, and hence it is often left out of prenatals or used in small amounts
If you eat food rich in choline daily (egg yolks and salmon), then this is may not be an issue for you
If you don't, find a prenatal with at least 200mg equivalent choline, or supplement separately.
Other considerations
Take your supplements with food as most nutrients are absorbed better this way and it's more gentle on your digestive system
If you can't tolerate large tablets, you may prefer to take a prenatal that is split into 6-8 smaller doses over the day, or find one that comes in a liquid or chewable form
If you are suffering from nausea/vomiting, take your supplements at the time of day that you feel best. And don’t worry if you miss a few days.
Take home messages:
There is no such thing as a ‘one-stop-shop’ supplement; they all have their pros and cons.
You are unique, and hence you nutrient needs are also unique. What works for your friend may not work for you.
See a prenatal dietitian for individual advice (for a personalised supplement plan, check out my Prenatal Supplement Package)
Written by Renee Jennings, prenatal dietitian, APD (updated 19/09/2024)
References:
1. Ahmed M. Abbas, Safaa A. Abdelbadee, Ahmed Alanwar & Sayed Mostafa (2019) Efficacy of ferrous bis-glycinate versus ferrous glycine sulfate in the treatment of iron deficiency anemia with pregnancy: a randomized double-blind clinical trial, The Journal of Maternal-Fetal & Neonatal Medicine, 32:24,4139-4145
2. Melamed N, Ben-Haroush A, Kaplan B, Yogev Y. Iron supplementation in pregnancy--does the preparation matter? Arch Gynecol Obstet. 2007 Dec;276(6):601-4.
3. The Royal Australian and New Zealand College of Obstetricians and Gynaecologists, Vitamin and mineral supplementation and pregnancy, 2008 (reviewed 2019), accessed 25 September 2023.
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6. Tsang BL, Devine OJ, Cordero AM, Marchetta CM, Mulinare J, Mersereau P, Guo J, Qi YP, Berry RJ, Rosenthal J, Crider KS, Hamner HC. Assessing the association between the methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism and blood folate concentrations: a systematic review and meta-analysis of trials and observational studies. Am J Clin Nutr. 2015 Jun;101(6):1286-94.
7. Greenberg, James A, and Stacey J Bell. Multivitamin Supplementation During Pregnancy: Emphasis on Folic Acid and l-Methylfolate. Reviews in obstetrics & gynecology vol. 4,3-4 (2011): 126-7.
8. Robert P. Heaney, Robert R. Recker, James Grote, Ronald L. Horst, Laura A. G. Armas, Vitamin D3 Is More Potent Than Vitamin D2 in Humans, The Journal of Clinical Endocrinology & Metabolism, Volume 96, Issue 3, 1 March 2011, Pages E447–E452.
9. Shieh A, Chun RF, Ma C, et al. Effects of High-Dose Vitamin D2 Versus D3 on Total and Free 25-Hydroxyvitamin D and Markers of Calcium Balance. J Clin Endocrinol Metab. 2016;101(8):3070-3078.
10. Kim J, Ahn CW, Fang S, Lee HS, Park JS. Association between metformin dose and vitamin B12 deficiency in patients with type 2 diabetes. Medicine (Baltimore). 2019 Nov;98(46):e17918. doi: 10.1097/MD.0000000000017918. PMID: 31725641; PMCID: PMC6867725.
11. Koletzko B, Cetin I, Brenna JT; Perinatal Lipid Intake Working Group; Child Health Foundation; Diabetic Pregnancy Study Group; European Association of Perinatal Medicine; European Association of Perinatal Medicine; European Society for Clinical Nutrition and Metabolism; European Society for Paediatric Gastroenterology, Hepatology and Nutrition, Committee on Nutrition; International Federation of Placenta Associations; International Society for the Study of Fatty Acids and Lipids. Dietary fat intakes for pregnant and lactating women. Br J Nutr. 2007 Nov;98(5):873-7.
