April 2024 Issue
Omega-3s & Childhood Development
By Alexandria Hardy, RDN, LDN
Today’s Dietitian
Vol. 26 No. 4 P. 16
A Comprehensive Review of the Research and Strategies to Boost Intake
The consumption of long-chain polyunsaturated fatty acids (PUFAs), particularly omega-3 fatty acids, is essential to healthy infant and toddler growth and development. They’re integral components of the cell membrane and are crucial for the optimal functioning of various physiological processes, including brain development, vision, and immune system modulation. Given that infants and toddlers undergo rapid and critical stages of growth, ensuring that they consume an adequate quantity of omega-3 fatty acids is paramount. Scientific evidence underscores the significance of incorporating these essential nutrients into the early stages of life to support cognitive development, immune function, and overall well-being in this vulnerable population. Developing a thorough understanding of long-chain PUFAs, especially omega-3 fatty acids, is a key aspect of promoting optimal health and development during the crucial early years of life.
Omega-3 fatty acids include EPA, DHA, and alpha-linolenic acid (ALA).1 ALA, a short-chain fatty acid, can be found in plant-based oils (eg, flaxseed, soybean, canola), nuts and seeds, and plant proteins (eg, walnuts, flax, chia, and tofu). The long-chain fatty acids DHA and EPA are plentiful in seafood and fish oils.2 ALA is the only essential omega-3 fatty acid that can’t be made in the body. ALA can be converted into EPA and DHA, yet the conversion process is limited and inefficient. A more efficient way to ensure adequate intake of ALA is through foods such as flaxseeds, chia seeds, walnuts, and certain vegetable oils.2 Though many omega-3 supplements are available for all ages, the purpose of this article is to focus on dietary sources of omega−3 fatty acids (including human breastmilk) and their impact on infant and toddler growth and development.
Impact on Early Development, Disease Prevention
The first year and a half of a child’s life is a stage marked by rapid development and important accumulation of omega-3 fatty acids, specifically in the brain and eyes.3 The infant brain grows from 350 to 925 g within the first 12 months, and nutrition is one of the three primary factors that regulate its healthy development.4
During the first six months, an infant’s nutrition sources are primarily human breastmilk, infant formula, or a blend of the two. Maternal dietary intake (particularly fatty acids like DHA) can influence the composition of the milk that’s passed along to a breast-feeding infant.5 These fluctuations in composition may affect neurological outcomes and growth of the nervous system.5 This is significant as the lipids found in expressed breastmilk provide nearly half of the energy a newborn consumes.6 Serum levels of DHA rise rapidly after dietary intake, with a peak occurring at six hours postconsumption, although levels can remain high for up to 72 hours.7
As infants become toddlers, their intake of omega-3 fatty acids has a positive effect on the following body systems and is associated with prevention of disease development.
• Neurological and visual systems. Omega-3 fatty acids continue to play a role in the development of children’s brain health and functionality and are also critical for visual development.1
• Immune, endocrine, cardiovascular, and pulmonary systems. Omega-3s provide essential structure within the cell membrane and serve as signaling molecules that influence the immune, endocrine, cardiovascular, and pulmonary systems.2
• Upper respiratory and allergic disease. The anti-inflammatory effect of omega-3s may lessen a child’s risk of developing upper respiratory infections and may decrease the likelihood of the development of allergies like asthma or eczema as they age.8,9 This may be possible through their impact on the immune system.8
• Mood regulation. Regular incorporation of omega-3s, particularly omega-3 rich fish, also may positively impact mood in children.10 A study published in Nutrients assessed 52 maternal milk samples to determine if their fatty acid composition affected infant temperament.11 Temperament was assessed using the Infant Behavior Questionnaire that was filled out by a parent; both the sample and the questionnaire were obtained three months postpartum.11 Researchers found that maternal milk with a higher omega-3 composition was associated with infants who displayed fewer external signs of distress and sadness.11
• Overweight and obesity. BMI also may be influenced by dietary consumption of fatty acids at a young age.10 Environmental studies have shown that omega-3 fatty acids may cause a decrease in fat deposits in adipose tissue and an increase in beta oxidation.12 This may provide evidence that a diet rich in omega-3 fatty acids could lessen the likelihood of weight gain and may prevent overweight and obesity as a child grows.12
Impact of EPA and DHA Intake on Infant Growth
A longitudinal study published in the journal Child: Care, Health, and Development evaluated the effects of maternal dietary fat consumption (particularly DHA and EPA) and its impact on growth during the first 12 months of life in 215 Iranian mothers and their infants.13 Participating mothers provided hind milk (milk expressed during the latter part of a breast-feeding session that typically contains a higher fatty acid concentration than fore milk expressed earlier in the feeding) samples when their infants were 6 to 12 weeks old and had their food intake evaluated via three-day dietary records.13 Their infants had their head circumference, length, and weight recorded every two months from birth to 6 months of age and at 12 months.13 At four months, EPA in the mother’s breastmilk was negatively correlated with infant weight.13 Similarly, at 12 months, the DHA in the mother’s breastmilk was negatively correlated with infant weight, though maternal dietary fat intake and the length of the infant were significantly correlated.13 This association also was found at six months but existed between maternal dietary fat intake and the weight of the infant.13 These findings suggest that the composition of breast milk, influenced by maternal dietary choices, may play a functional role in shaping early infant growth—specifically length and weight.13 However, the recommendation for longer follow-up indicates the need for continued research to better understand the implications of maternal diet on infant development beyond the observed time points.
FINS-KIDS, a randomized controlled trial published in BMC Medicine, evaluated fine motor functionality and the cognitive impact of feeding a lunch of fatty fish three times per week to Norwegian preschoolers compared with traditional meat proteins.14 The experimental group consisted of 105 children, who ate 978 g of herring or mackerel three times per week, and the control group consumed 850 g of lamb, chicken, or beef as their primary proteins for 16 weeks.14 The children were evaluated using the Wechsler Preschool and Primary Scale of Intelligence, third edition, for cognitive reasoning and the Nine-Hole Peg Test, which studied their fine motor skills.14 By the conclusion of the study, children in the experimental group showed a significant increase in their red blood cell omega-3 fatty acid levels and an improvement in overall scores on the cognitive function and fine motor assessments.14 The authors concluded that though there was no significant difference between the fish and meat groups, the dietary intake of DHA likely helped improve processing and coordination found in the fish group.14
Areas of Future Research
There’s a lack of long-term, randomized controlled trials on the effects of dietary omega-3 consumption in infancy through toddlerhood. More research is needed to determine what impact consuming dietary sources of omega-3s (vs supplementation) can have on infant and child growth and development. Much research exists on the impact of DHA and EPA intake in adults, but it’s yet to be determined if an increased dietary intake of omega-3s early in life can be similarly extrapolated. More specifically, the second year of a child’s life (aged 12 to 24 months) is considered a time of considerable physical and mental growth and maturation, and there’s evidence that dietary shifts can impact this development.3 To confer the most robust and long-lasting benefits, regular consumption of dietary sources of omega-3 fatty acids may be necessary.3 Translating future research into a population-based intervention could be a helpful tool to better provide education and recommendations for omega-3 intake throughout the life span.5
Current Recommendations and Average Intakes
Omega-3 fatty acids like EPA and DHA are primarily present in seafood, such as shellfish, salmon, herring, and different types of algae.1 Consuming servings of seafood two to three days per week will help adults meet their goal of 250 mg to 500 mg of EPA and DHA per day. The American Heart Association recommends two servings (3 oz cooked or 3/4 cup flaked) of fish weekly for adults.15 A 1-oz serving of fish is appropriate for children aged 1 to 3. Children also are encouraged to consume two servings of omega-3-rich fish per week. For children and adults who eat a plant-based diet, 1 T of flaxseed or canola oil or 1 oz of chia seeds or flaxseeds and walnuts will help them meet their needs.2 Adequate intake for omega-3 fatty acids is 0.5 g to 0.7 g for children aged 1 to 3 and 0.9 g for children aged 4 to 8.2 Adequate intake for infants includes sources of ALA, DHA, and EPA (essential and nonessential fatty acids), while the toddler-specific adequate intake references only ALA as an essential fatty acid.2
Increasing Intake in Infants and Toddlers
Examples of seafood naturally rich in omega-3 fatty acids include sardines, herring, anchovies, mackerel, black cod, salmon, bluefin tuna, clams, oysters, and striped bass; they range from 0.10 g to 1.83 g of DHA and EPA per serving.2,15
Plant-based sources of omega-3 fatty acids include chia seeds, walnuts, flaxseeds, edamame, algae, and seaweed. It’s important to note that plant-based omega-3s (with the exception of seaweed like kelp, nori, and algae) are technically ALA, which must be converted to DHA and EPA in the body. One tablespoon of flaxseed oil contains 7.26 g of ALA, and 1 oz of chia seeds boasts 5.06 g. ALA may confer heart health benefits, improved cognitive functioning, anti-inflammatory properties, a decreased risk of developing age-related macular degeneration, and contribute to cell membrane integrity.
Infants who aren’t yet eating solid foods depend on breastmilk and fortified formula primarily to meet their omega-3 fatty acid needs.1 The Mental Development Index determined that formulas containing at least 0.35% DHA result in healthier brain development.1 For breast-fed infants, the higher the mother’s levels of plasma DHA, the better the outcomes for the infant.1,16 Weekly fish intake is positively associated with higher DHA levels in breastmilk and should be encouraged above plant-based sources if fish fits within the mother’s budget as well as cultural and personal preferences.7
Mothers who consume a vegan diet tend to have significantly higher levels of unsaturated fatty acids and total omega-3 fatty acids in their breastmilk and a lower omega-6 to omega-3 ratio than omnivorous and vegetarian mothers, though DHA concentrations in breastmilk were low across all maternal diet patterns. This is attributed to low seafood intake and supplement use, as DHA is commonly found in marine sources.17 These findings underscore the impact of maternal diet on the nutritional composition of breastmilk. While vegan breastmilk demonstrated certain advantages in terms of unsaturated fats and omega-3s, the lower DHA concentrations indicate a potential need for supplementation or dietary adjustments to ensure optimal infant development. As always, it’s important for mothers, regardless of dietary pattern, to consult with their health care professionals for personalized guidance on nutrition during breast-feeding.17
Counseling Strategies for Dietitians
The typical Western diet isn’t naturally high in omega-3 fatty acids and favors omega-6 fatty acids found in sesame, soy, and corn oils.3 This can be problematic since both omega-3 and omega-6 fatty acids share enzymes for their conversion, particularly delta-6 desaturase. A higher intake of omega-6 fatty acids can lead to increased production of arachidonic acid, an omega-6 fatty acid, at the expense of EPA and DHA synthesis from ALA. Dietitians can help educate clients on the different types of cooking oils available and help them understand how to best incorporate omega-3-rich varieties like canola, flaxseed, or soybean oil into their dietary patterns and preferences. Research shows that consuming a balanced ratio of omega-3 to omega-6 fatty acids can positively impact cognitive function and memory.3 It’s important to note that clients with higher disposable incomes and levels of education are more likely to incorporate dietary sources of omega-3 fatty acids into their diets, while those with a lower socioeconomic status and less education may be less inclined to select foods abundant in omega-3s.3
Many pregnant and lactating women in the United States consume a traditional Western diet and are unlikely to pass adequate amounts of omega-3 fatty acids on to their infants through breastmilk without education.16 A meta-analysis conducted in 2007 found that while the international average of DHA in breastmilk was 0.32%, breast-feeding mothers in the United States typically have lower levels (0.20%).18 The following year, international dietary recommendations were established for the pregnant and lactating population that encouraged daily consumption of 200 mg of DHA.18 The International Breastfeeding Journal published a community-based study on fatty acid education to explore if these recommendations would prompt behavior change in 60 new breast-feeding mothers.18 The researchers discovered that upon receiving education about their own levels of DHA alongside the recommended intake for lactating mothers, there was an increase in the DHA concentration of their breastmilk within a month.18 Due to the study’s small sample size and the homogeneous population, it’s difficult to extrapolate the data to the general public. But the positive response the educational session produced should encourage dietitians.18 For those who work with pregnant or breast-feeding women or with a pediatric population, it may be worthwhile to create simple resources to use during a nutrition education session.
Natural Food Sources
Dietitians also can provide nutrition education on natural sources of omega-3 fatty acids and help clients determine how to access these foods and make them relevant to their current intake. For example, if a client typically uses olive oil when cooking, switching to canola or flaxseed oil may be an opportunity to increase omega-3 intake without dramatically altering the taste of the food. Chia seeds are another plant-based food that provide an omega-3 boost. Clients can sprinkle chia seeds onto oatmeal, yogurt, and baked goods. Other inexpensive and shelf stable sources of omega-3s include tinned fish (eg, sardines, tuna, salmon, and mackerel), soybeans, and walnuts.10
For infants and toddlers, clients can introduce salmon or tuna burgers or cod nuggets to familiarize them with omega-3-rich foods.10 One important factor to note is that certain fish, which are excellent sources of omega-3 fatty acids, are also high in mercury, a neurotoxin that can be harmful to the developing nervous system. These include swordfish, tilefish, king mackerel, and bigeye tuna and should be avoided by pregnant women and young children. Therefore, babies and toddlers and pregnant and lactating women should vary the type of fish they consume to minimize the risk of mercury poisoning. According to the Joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives, a tolerable intake of 1.6 μg/kg body weight per week has been established for methylmercury for in utero infants and children.19 Low mercury seafood choices include clams, oysters, scallops, pollock, flounder, salmon, tilapia, and cod.20 Plant-based ideas for incorporating omega-3s into a toddler’s diet can be as simple as mixing a teaspoon of flaxseed oil into smoothies or nut butter and stirring ground flaxseed into oatmeal, applesauce, or soups.10
Bottom Line
Omega-3 fatty acids are crucial for the healthy development of the central nervous system, vision, and mental health, and also may support the immune system in infants and toddlers.1,8 Foods rich in omega-3 fatty acids are readily available at various price points to meet many different dietary patterns and can be adapted to suit a variety of ages and cultural preferences.
Lactating mothers who may provide the sole source or majority of an infant’s nutrition should be mindful that the quality of their diet can affect which fatty acids are present and passed on to their infant.20 Parents, whose infants and toddlers consume table food in addition to or instead of breastmilk or infant formula, are encouraged to provide a variety of omega-3-rich foods to their children to support healthy neural and body development as they mature.
— Alexandria Hardy, RDN, LDN, is a nutrition educator and the owner of Pennsylvania Nutrition Services, an insurance-based private practice located in Lancaster, Pennsylvania. She’s a freelance writer and speaker and volunteers as a coordinator for the Power Packs Project, a nonprofit dedicated to ending hunger in local schools.
References
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12. Simopoulos AP. An increase in the omega-6/omega-3 fatty acid ratio increases the risk for obesity. Nutrients. 2016;8(3):128.
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16. Barrera C, Valenzuela R, Chamorro R, et al. The impact of maternal diet during pregnancy and lactation on the fatty acid composition of erythrocytes and breastmilk of Chilean women. Nutrients. 2018;10(7):839.
17. Perrin MT, Pawlak R, Dean LL, Christis A, Friend L. A cross-sectional study of fatty acids and brain-derived neurotrophic factor (BDNF) in human milk from lactating women following vegan, vegetarian, and omnivore diets. Eur J Nutr. 2019;58(6):2401-2410.
18. Juber BA, Jackson KH, Johnson KB, Harris WS, Black ML. Breastmilk DHA levels may increase after informing women: a community-based cohort study from South Dakota USA. Int Breastfeed J. 20166;12:7.
19. Bose-O’Reiliy S, McCarty KM, Steckling N, Lettmeier B. Mercury exposure and children’s health. Curr Probl Pediatric Adolesc Health Care. 2010;40(8):186-215.
20. Marshall NE, Abrams B, Barbour LA. The importance of nutrition in pregnancy and lactation: lifelong consequences. Am J Obstet Gynecol. 2022;226(5):607-632.