Role of Omega-3 Fatty Acids in Maternal, Fetal, Infant and Child Wellbeing

Ellen Mozurkewich; Deborah R Berman; Julie Chilimigras

Expert Rev of Obstet Gynecol. 2010;5(1):125-138.

Abstract and Introduction

Abstract

Many pregnant women avoid dietary fish, the premier source of omega-3 fats, owing to fear of industrial contaminants. This concern, combined with a Western diet relatively deficient in omega-3 fatty acids, has created an imbalance of omega-3 compared with omega-6 fats. This imbalance may lead to a proinflammatory state that contributes to a number of complications, including preterm birth, pregnancy-induced hypertension and postpartum depression. Fetal deficiency of omega-3 fats may place infants at risk for allergic disease and suboptimum neuropsychiatric development. Although a number of studies of omega-3 fatty acid supplementation are suggestive of benefit, other studies have not shown a benefit. More research is needed to elucidate the risks and benefits of fish consumption and dietary omega-3 supplementation in pregnancy.

Introduction

Since the mid-19th Century, major dietary changes have occurred in the industrial world. There has been a significant decrease in vital micronutrients, such as omega-3 polyunsaturated fatty acids, and an increase in other fats, most notably omega-6 fatty acids.^[1] Prior to industrialization, humans obtained a significant proportion of dietary fat from fish, wild game and leaves. The modern diet, emphasizing grains, dairy products and grain-fed meats, has replaced these traditional food sources. As a result of these changes, there have been increases in total fat, saturated fat and linoleic acid.^[2] Owing to the differing biochemical derivatives of these polyunsaturated fats, the modern diet has been observed to be relatively proinflammatory. Inflammation may play an important role in a number of pregnancy-related morbidities, including preterm labor, preterm premature rupture of membranes, chorioamnionitis, cerebral palsy and depression during pregnancy and postpartum. This review summarizes existing knowledge regarding dietary omega-3 long-chain polyunsaturated fatty acids (LC-PUFA) and their current and potential applications in these aforementioned and other pregnancy-related morbidities.

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Table 1. Omega-3 fatty acids and industrial contaminants in commonly eaten fish and shellfish.
Type	EPA + DHA (mg/serving) (oz)	EPA + DHA (mg/100 g) (3.5 oz)	Mercury (µg/g) (ppm)	PCBs (ng/g) (ppb)
Anchovy	1165 (2)	2055	< 0.05
Catfish, farmed	253 (5)	117	< 0.05	< 50
Cod, Atlantic	284 (6.3)	158	0.10
Fish burger (fast food)	337 (2.2)	546	< 0.05	8
Fish sticks, frozen	193 (3.2)	214	< 0.05
Halibut	740 (5.6)	465	0.25
Herring, Atlantic	1712 (3)	2014	< 0.05
Mackerel, Atlantic	1059 (3.1)	1203	0.05
Mackerel, King	618 (5.4)	401	0.73
Mahimahi	221 (5.6)	139	0.15
Pollock, Alaskan	281 (2.1)	468	< 0.05
Salmon, farmed	4504 (6)	2648	< 0.05	15–51
Salmon, wild	1774 (6)	1043	< 0.05	0.5–5
Sardines	556 (2)	982	< 0.05	22–57
Shark	583 (3)	689	0.99
Snapper	546 (6)	321	0.19
Swordfish	868 (3.7)	819	0.98
Trout	581 (2.2)	935	0.07	11
Tuna (light/skipjack)	228 (3)	270	0.12	45
Tuna (white/albacore)	733 (3)	862	0.35	100
Clams	241 (3)	284	< 0.05	2–3
Crab	351 (3)	413	0.09	6
Lobster	71 (3)	84	0.31
Mussels	665 (3)	782	< 0.15	0.8–7
Oysters	585 (3)	688	< 0.05	0.8–17
Scallops	310 (3)	365	< 0.05
Shrimp	267 (3)	315	< 0.05	0.2–2

DHA: Docosahexaenoic acid; EPA: Eicosapentaenoic acid; PCB: Polychlorinated biphenyls; ppb: Parts per billion; ppm: Parts per million.
Adapted from.^[101]

Table 2. Results of clinical trials of omega-3 fatty acid supplementation.
Parameter	Results
Preterm birth:
< 37 weeks	No benefit*
< 34 weeks	Likely benefit^§
Intrauterine growth restriction (small for gestational age)	No benefit
Preeclampsia	No benefit
Perinatal depression:
– Prevention	No benefit
– Treatment	Conflicting results^¶
Neurodevelopmental outcomes:
– Term	Conflicting results
– Preterm	Conflicting results
Prevention of allergic disease	Conflicting results

*The majority of the available clinical trials show no benefit for the intervention.
^§The majority of the available clinical trials show a benefit for the intervention.
^¶Clinical trial results are mixed, with some trials showing benefit and others not.

Box 3. Biologic activities of omega-3 fatty acids.
Decrease proinflammatory cytokine production Precursors of resolvins and neuroprotectins Improve membrane fluidity May counter or promote apoptosis, depending on circumstance Regulate gene expression Act as antioxidants Quicken neurotransmission Modulate intracellular signaling

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