The role of dietary fats during pregnancy

The role of dietary fats during pregnancy

Dietary fats play an important role in our health, providing a concentrated form of energy, enabling the absorption of certain nutrients, and providing essential fatty acids that the body cannot make. This article covers the different types of fat in the diet, and practical steps to helping pregnant women include essential fats to support the development of their baby.
  1. Different types of fats
  2. Essential fatty acids
  3. Role of essential fats in pregnancy
  4. Sources of essential fats in pregnancy
  5. Omega 3 supplements
Different types of fats A small amount of fat is an essential part of a healthy balanced diet at any stage of life, including pregnancy. Dietary fat helps the body to absorb vitamins A, D, E and K – these are known as fat-soluble vitamins, and without fat the body cannot utilise these nutrients (1). There are 2 main types of fat found in food: saturated fat and unsaturated fat. Saturated fats are mainly found in fatty cuts of meat, meat products, some savoury snacks, chocolate, biscuits, cakes and pastries (1). Higher intakes of saturated fats have been associated with an increase in LDL cholesterol in the blood, which in turn is associated with an increased risk of heart disease. Unsaturated fats have been associated with lowering cholesterol level and reducing the risk of heart disease (2). Unsaturated fats can be divided further into mono-unsaturated and poly-unsaturated, depending on the chemical structure. Mono-unsaturated fats can be found in olive oil, rapeseed oil, avocados, and some nuts, such as brazil nuts, almonds and pecans. Poly-unsaturated fats can be mainly found in vegetable oils, and oily fish (1). Essential fatty acids There are 2 main types of poly-unsaturated fatty acids: Omega-3 and Omega-6. The body can make most of the fatty acids it needs from other fats that are consumed, except for two, which are deemed essential fatty acids: alpha linolenic acid (ALA omega-3) and linoleic acid (LA omega-6). These fatty acids must be provided by the diet (3). LA omega-6 fatty acids can be found in certain plant foods, such as vegetable oils and some nuts. ALA omega-3 fatty acids can be found in linseed/flaxseed oil, rapeseed oil and walnuts (1). These essential fatty acids are precursors to long-chain polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), which have important roles in the growth, development and health of the foetus (3). As well as being made by the body from ALA, DHA can be found in food sources, the richest being oily fish such as salmon, mackerel, sardines and trout (1,3). Role of essential fats in pregnancy During pregnancy, dietary intake of essential fats, contribute to the health and development of the foetus, in particular the development of the brain, eyes and nervous system (4). Fat is the main source of energy for a developing baby’s and makes up almost 60% of their brain (5). Omega 3 fatty acids are also an important structural components of cell membranes and are essential to the formation of new tissues (4). Because the body cannot make the omega-3 fats needed, it is essential that they come from the maternal diet. Dietary intake during pregnancy must be sufficient to meet both the mother’s requirements as well as those of the developing foetus. Some studies have also shown that a deficiency in these essential fatty acids can be linked to complications in pregnancy (6), with some research suggesting that diets rich in seafood, in particular oily fish, may result in fewer preterm births (7). There is also some evidence to suggest that mothers who use omega-3 supplementation during pregnancy and breastfeeding may protect their children against certain allergies (8,9) However, the research in this area is varied and not strong enough to warrant a change in recommendations. What is clear is that the levels of fatty acids in babies at birth, are closely correlated to levels of the mother (4). In practice, emphasis should be on ensuring adequate intake during pregnancy, particularly for mothers carrying multiple babies, or having pregnancies in quick succession. Sources of DHA in pregnancy The most concentrated food sources of DHA are found in oily fish – salmon, sardines, mackerel, and trout. During pregnancy it is recommended to limit the consumption of oily fish to no more than 2 portions a week, as oily fish can also contain low levels of pollutants that can build up in the body (3). Other forms of omega-3 that can be converted by the body to DHA can be found in nuts and seeds (walnuts, pumpkin and chia seeds) and some vegetables oils such as rapeseed and flaxseed oil. Omega-3 supplements in pregnancy For women consuming adequate omega-3 fatty acids in the diet, the benefits of taking an additional supplement during pregnancy are not well supported by research (4,10). If women do decide to take a supplement, it is important to ensure that it is suitable for pregnancy, as some fish oil supplements contain a high amount of vitamin A (such as cod liver oil), which should be avoided (3). An omega 3 supplement should provide the same amount of omega-3 as would be consumed in 2 portions of oily fish per week – that’s about 450-500mg EPA (another type of omega-3 fatty acid) and DHA per dose. (11, 12) Algal-oil omega-3 supplements are available for those who do not consume animal products.
About the Author: Katie Angotti is a Registered Public Health Nutritionist, specialising in maternal, infant and child health. Katie has worked with children and families in the NHS, in the baby food industry and now works in private practice with pregnant women and parents.   References
  1. NHS (2021) Fat: The Facts. [online] Accessed at: https://www.nhs.uk/live-well/eat-well/different-fats-nutrition/
  2. SACN (2019) Saturated Fats and Health. [online] Accessed at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/814995/SACN_report_on_saturated_fat_and_health.pdf
  3. British Nutrition Foundation (2021). Fat. [Online] Accessed at: https://www.nutrition.org.uk/healthy-sustainable-diets/fat/
  4. British Nutrition Foundation (2006). Nutrition in Pregnancy. Nutrition Bulletin 31
  5. Chang CY, Ke DS, Chen JY. (2009) Essential fatty acids and human brain. Acta Neurol Taiwan.18(4):231-41
  6. Irwinda R, Hiksas R, Siregar AA, Saroyo YB, Wibowo N. (2021) Long-chain polyunsaturated fatty acid (LC-PUFA) status in severe preeclampsia and preterm birth: a cross sectional study. Sci Rep. 19;11(1)
  7. Olsen SF, Østerdal ML, Salvig JD, Weber T, Tabor A, Secher NJ. (2007) Duration of pregnancy in relation to fish oil supplementation and habitual fish intake: a randomised clinical trial with fish oil. Eur J Clin Nutr. 61(8):976-85
  8. Swanson D, Block R, Mousa SA. (2012) Omega-3 fatty acids EPA and DHA: health benefits throughout life. Adv Nutr. 3(1):1-7.
  9. Olsen SF, Østerdal ML, Salvig JD, Mortensen LM, Rytter D, Secher NJ, Henriksen TB. (2008) Fish oil intake compared with olive oil intake in late pregnancy and asthma in the offspring: 16 y of registry-based follow-up from a randomized controlled trial. Am J Clin Nutr. 88(1):167-75
  10. Serra R, Peñailillo R, Monteiro LJ, Monckeberg M, Peña M, Moyano L, Brunner C, Vega G, Choolani M, Illanes SE. (2021) Supplementation of Omega 3 during Pregnancy and the Risk of Preterm Birth: A Systematic Review and Meta-Analysis. Nutrients.13(5)
  11. British Dietetic Association (2021) Omega 3. [Online] Accessed at: https://www.bda.uk.com/resource/omega-3.html
  12. Plant Based Health Professionals (2021) A Healthy Vegan Pregnancy. [Online] Accessed at: https://plantbasedhealthprofessionals.com/wp-content/uploads/Healthy-Pregnancy-Poster-A4-5.pdf
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