How To Achieve a Desirable Profile of Essential-Fatty Acids in Formula

How To Achieve a Desirable Profile of Essential-Fatty Acids in Formula

Introduction

This article will explore the evolution of infant formula (IF), outline current regulations on composition and examine evidence suggesting a potential association between the source of fat used in IF and infant health outcomes. The article will conclude with practical considerations for healthcare professionals (HCPs). The first 1,000 days of life provides a window of opportunity for adequate nutrition to promote healthy growth and development (1). The World Health Organisation (WHO) promotes exclusive breastfeeding as the best form of nutrition for infants throughout their first six months of life. Wherever possible, breastfeeding should be offered within the first hour of life and on demand thereafter, continuing alongside introduction of solids until the child is at least two years old (2). The composition of breastmilk is influenced by maternal and environmental factors, including maternal diet, stage of lactation and storage of breast milk (3). Table 1 compares the macronutrient composition of mature breast milk (in liquid and powder form) with milk formula containing milk fats or vegetable oils for full term infants. Table 1: The Macronutrient Composition of Mature Breast Milk (in liquid and powder form) Compared with Milk Formula Containing Milk Fats or Vegetable Oils for Full Term Infants
Breastmilk liquid (/100ml) (4) Breastmilk (as powder - Calculated) (/100g) Milk formula containing milk fat (/100g) (5) Milk formula comprised of vegetable oils (/100g) (6)
Protein (g) 1.08 8.9 10.1 9.6
Fat (g) 3.46 28.5 28 24.4
Carbohydrate (g) 7.09 58.3 56 51
Total solids (g) 11.86 97.5 97.5 97.5
  Although support should be given to all pregnant women and mothers to initiate breastfeeding, it is recognised that breastfeeding is not always possible. Infants who are not breast fed should be given an infant formula as a suitable breast-milk substitute. While European regulations mean there is little variation in the nutritional content of IFs (see Table 2), the predominant difference between commercial brands of IFs lies in the source of fats used. Over recent year’s interest in healthier lifestyles and environmental sustainability have driven a change in perspective on food quality. A recent study found the main health factors influencing consumer choice include ingredients (source and quality), nutritional content and minimal use of additives. Factors influencing consumer choice include food origin and environmentally friendly production methods (7). This shift in consumer focus is evident in the IF market, which has seen the emergence of brands focusing on natural and sustainably sourced ingredients (8).  

The Evolution of Vegetable Fat usage in IF

Development of breastmilk substitutes began in the early 19th century. The timeline below illustrates the significant changes to the fat composition of IF formulations over the past century. The origin of Vegetable fat usage in IF:
  • “Fat filled milk powder” (FFMP) (which is a blend of skimmed milk powder and vegetable fats) was developed for human consumption 100 years ago in Malaysia as a cheaper export substitute to cow’s full fat milk powder (9).
  • 1923: the USA “Filled Milk Act” banned the use of FFMP as it was deemed ‘injurious to public health’ (10).
  • 1970's: ‘Volac’, a manufacturer of FFMP in the UK, used it as feed for livestock. Brands including “Millac” sold FFMP for human consumption as an affordable alternative to exporting cow’s full fat milk powder (11).
  • 1985: IF companies incorporated FFMP into their recipes to reduce formulation costs (12).
  • 2014: A Swedish study supplemented IF with milk fat globule membranes (MGFMs), with the aim of replicating the fatty acid profile of breast milk. This resulted in similar lipid profiles between formula-fed and breast-fed infants at 12 months of age (13), although there were some study limitations (e.g., different fasting times for different groups).
  • Present: Some IFs have started to use bovine milk fat (from full cream cow’s milk); further research into infant health outcomes is indicated (14).
 

Current Guidance on the Nutritional Composition of Infant Formula

The nutritional composition of IFs is regulated by the European Food Safety Authority to safeguard nutritional intake during infancy (see table 2). Table 2: The macronutrient recommendations of infant formula (Commission Delegated EU Regulations 2016/127) (15)
Protein content (g/100 kcals) Lipids (g/100 kcals) Carbohydrate (g/100 kcals) Energy (kcals/100mls)
Minimum Requirement 1.8 4.4 9 60
Maximum Requirement 2.5 6 14 70
  Compositional requirements of IF are based on provision of energy and essential fatty acids (EFAs) to promote adequate growth and development. The EFAs may be sourced from fats of dairy or vegetable origin (16). IFs must contain the EFAs linoleic acid and alpha linolenic acid, and more recently docosahexaenoic acid (15).  

Why Does the Source of Fat Matter?

Lipids (fats) are the main energy source during infancy. The main difference in composition between IFs available in the UK relates to the source of fat (vegetable or dairy based). Mature human breast milk contains approximately 34%-47% saturated fatty acids (17). A significant difference between breast milk and IF is their saturated fatty acid (SFA) profile. The most common SFAs in IF and breast milk are 12, 14, 16, and 18 carbon chain lengths (17). Table 3 illustrates the similarity of fatty acid profiles between cow’s milk fat based IF and human breast milk when compared with vegetable fat-based IFs.   Table 3: Differences in fatty acid composition of human breast- milk and formulas based on cow’s milk fat or vegetable fat (18)
Fatty Acids (g/100g FA) Human Breast Milk Cow’s Milk Fat Formula* Vegetable Fat Formula**
C12:0 (Lauric acid) 4.40 3.04 13.07
C14:0 (Myristic acid) 6.27 8.62 5.43
C15:0 (Pentadecanoic acid) 0.43 0.85 0.05
C16:0 (Palmitic acid) 22.0 24.76 26.50
C18:0 (Stearic acid) 8.06 8.62 3.86
*Ingredients are cow’s milk fat and corn oil **Ingredients are palmolein, soybean oil and residual amounts of cow’s milk fat.   The structure of triglycerides in human breast milk and cow’s milk fat both differ significantly from those of vegetable fats used in IFs. In human breast milk fat and cow’s milk fats, palmitic acid (C:16:0) is predominantly esterified in the sn-2 position, whereas in vegetable fats it is found in the sn-1 and sn-3 positions. Using cow’s milk fats in IF provides a higher ratio of palmitic acid located at the sn-2 position (the typical configuration in human breast milk) than IFs which predominantly use vegetable fats (19).  

Fat Sources in IF and Effects on Health - A Review of Current Evidence

Research has highlighted a potential association with the use of palm oil in IF, leading to reduced calcium absorption, reduced bone mineralisation and harder stools (20,21,22). Additionally, a number of recent studies have focused on the health effects of the various fat sources used within IF (a summary of recent studies is displayed in Table 4). Table 4: Recent evidence relating to the source of fat in infant formula and the effects on health
Health Topic Summary of Findings Study Considerations
Cognition Three double-blind randomized controlled trial (DBRCT) found:   1. IF supplemented with lipid rich MFGMs given to infants 2-6 months old improved cognitive performance at 24 weeks old (23). 2. IF supplemented with MFGMs were given to infants <2-6 months-old. At 12 months, infants in the MFGM group achieved higher cognitive performance than controls but did not differ from the breastfed group (24).   3. IF containing MGFMs resulted in improved psycho-behavioral development in children at age two and a half, compared to those who were fed with a standard IF (25). ● Small sample size in some of these DBRCTs. ● Difficult to evaluate the effect of a single nutrient as these IFs were developed with additional human milk oligosaccharides and synbiotics. ● Difficult to assess the extent of the effect MGFM had on behavioral development due to other confounding factors including psychosocial issues ● Hard to compare these studies due to variations in the IF used and population groups studied.   At present, there is insufficient evidence for a general recommendation on IF MFGM supplementation to be made.
Improved stool consistency and reduced incidence of nighttime distress An IF containing milk fat resulted in more frequent 'soft-formed', mustard-coloured stools compared with an IF containing vegetable fat. In addition, there were fewer incidences of night-time distress in infants given IF containing milk fats. It was assumed this was secondary to reduced gut discomfort (26). ● The short study duration (7 days) is insufficient to form a conclusion in order to change clinical practice. ● Suggested benefits of IF supplemented with milk fats cannot be exclusively attributed to the effect of the fat blend due to potential confounders (e.g., source of ingredients and processing.)
Metabolism A systematic review concluded that IF made without palm oil resulted in increased absorption of fat, palmitic acid and calcium. Bone mineral content was significantly higher in infants fed with a non-palm oil containing IF (21). This is thought to be due to palm oil causing decreased absorption of palmitic acid (PA). Unabsorbed PA forms calcium fatty acid soaps, resulting in reduced calcium absorption. This can cause harder stool consistency, increased calcium losses in stools and reduced bone mineral density (21). ● Nine studies were included in this review, each reporting variability in the effect size between non-palm oil and palm oil IF groups.
A meta-analysis of nine RCTs indicated that infants fed with a non-palm oil containing IF had softer stools and similar stool frequencies compared with infants fed with palm-oil containing IF (22). ● Nine studies were included in this review, each with differences in study types and design. No studies made a comparison with human breast milk-fed infants.
A recent review examined the relationship between palm oil and fat/calcium absorption. All except one study concluded the absence of palm oil/olein as a source of fat in IF, resulted in increased fat/calcium absorption, irrespective of the protein source (27). ● Six studies is a relatively small number to form a clinical conclusion. ● Sample sizes of the studies were small (10-30 participants)
 

Clinical Guidelines and Position Statement on Fats used in Infant Formulas

A recent position paper by the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) examined IFs containing palm oil or beta-palmitate. Comparison between formulas using palm oil and formulas using other fat sources (i.e., cow’s milk fats) were limited. The paper concluded “There is insufficient evidence to suggest that palm oil should be avoided as a source of fat in infant formulas for health reasons” (28). This was later challenged in a rebuttal statement which stated that in view of multiple studies having demonstrated the use of palm oil in IF impairs fat and calcium absorption and reduces bone density, caution should be exercised when adding palm oil to IF (29). ESPGHAN responded by stating evidence against the use of palm oil in IF is not conclusive. The committee has suggested further evidence in the form of well-designed RCTs is needed to examine the possible long-term health effects of palm oil-based IFs (30). The European Food Safety Authority (EFSA) states palm oil may contain glycidyl fatty acid esters (GE) and 3-monochloropropanediol [3-MCPD], which can be carcinogenic. EFSA suggested that exclusively formula-fed infants may slightly exceed the recommended daily intake of 2μg/kg/day of 3-MCPD. IFs containing other vegetable or cow’s milk fats have relatively low concentrations of 3-MCPD. However, the EFSA notes that oil blends used in IF contain levels of 3-MCPD and GE within toxicity regulations (31).  

Practical Considerations for Clinical Practice

The decision on how to feed an infant is one of the most important decisions parents can make. HCPs should educate and support parents to make an informed decision regarding their chosen method of infant feeding (i.e., exclusive breastfeeding or formula feeding). Non-judgmental discussions on the benefits of breastfeeding and effective support should be provided to parents to enable exclusive breastfeeding for the first six months of life where possible (2). Although breastfeeding is best for infants, it is not always possible. Parents should be given adequate education and support with the introduction of formula feeding, including education in how to safely prepare IF and responsive bottle feeding (32). It is the role of the HCP to acknowledge and overcome common challenges parents face when selecting an appropriate IF. The HCP should acknowledge the wide range of information available, variation in price point of IFs and the guilt often experienced by mothers who do not breastfeed. It is helpful to reiterate that, if able, providing even a small amount of breastmilk is beneficial (32). Dietitians have a responsibility to translate nutritional science to parents and provide reassurance that all IF available in the UK meet compositional regulations; the highest price point is not necessarily representative of the best product. Paediatric dietitians are well-placed to educate parents on interpretation of ingredient labels and nutritional claims when selecting an IF. It is helpful to encourage parents to start thinking holistically about infant nutrition. Discussions could explore the parent’s cultural, ethical and dietary requirements. Caution should be exercised to ensure that all HCPs are working within the ‘WHO code of marketing of breastmilk substitutes’ (33). An understanding of the IF market, with specific focus on the compositional differences, for example the source of lipids (fats) used and how it may benefit specific patient cohorts would enable HCPs to help parents make an informed decision regarding their choice of IF if breastfeeding is not possible.  

Conclusion

The complex lipid (fat) profile of human breast milk continues to be the focus of scientific research. Comparison of the composition of human breast-milk fat, cow’s milk fat and vegetable fats and their implications for infant health remain the subject of debate. Using cow’s milk fats in IF provides a higher ratio of palmitic acid located at the sn-2 position (the typical configuration in human breast milk) than IFs which predominantly use vegetable fats (19). Despite emerging evidence suggesting the benefits of transitioning from vegetable fats to cow’s milk fats as the principal fat source of IFs, further research is needed. In order to help families navigate different IF brands, clinical guidelines should continue to be updated according to the evolving evidence base. HCPs should be encouraged to critically analyse ingredients used within IFs and translate this into accessible information to help parents choose a formula that meets the needs of their child. About the Author: Annina is a UK Registered Dietitian with experience in gastrointestinal disorders, diabetes and weight management and in adult and paediatric settings. About the Editor: Clare Thornton-Wood is a qualified dietitian with a specialist interest in paediatric nutrition, registered with the British Dietetics Association, and a member of the BDA Freelance Dietitians Group.

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