Influence of dietary source of docosahexaenoic and arachidonic acids on their incorporation into membrane phospholipids of red blood cells in term infants

The Impact of Linoleic Acid on Infant Health in the Absence or Presence of DHA in Infant Formulas

Both linoleic acid (LA) and α-linolenic acid (ALA) are essential dietary fatty acids, and a balanced dietary supply of these is of the utmost importance for health. In many countries across the globe, the LA level and LA/ALA ratio in breast milk (BM) are high. For infant formula (IF), the maximum LA level set by authorities (e.g., Codex or China) is 1400 mg LA/100 kcal ≈ 28% of total fatty acid (FA) ≈ 12.6% of energy. The aims of this study are: (1) to provide an overview of polyunsaturated fatty acid (PUFA) levels in BM across the world, and (2) to determine the health impact of different LA levels and LA/ALA ratios in IF by reviewing the published literature in the context of the current regulatory framework. The lipid composition of BM from mothers living in 31 different countries was determined based on a literature review. This review also includes data from infant studies (intervention/cohort) on nutritional needs regarding LA and ALA, safety, and biological effects. The impact of various LA/ALA ratios in IF on DHA status was assessed within the context of the current worldwide regulatory framework including China and the EU. Country averages of LA and ALA in BM range from 8.5-26.9% FA and 0.3-2.65% FA, respectively. The average BM LA level across the world, including mainland China, is below the maximum 28% FA, and no toxicological or long-term safety data are available on LA levels > 28% FA. Although recommended IF LA/ALA ratios range from 5:1 to 15:1, ratios closer to 5:1 seem to promote a higher endogenous synthesis of DHA. However, even those infants fed IF with more optimal LA/ALA ratios do not reach the DHA levels observed in breastfed infants, and the levels of DHA present are not sufficient to have positive effects on vision. Current evidence suggests that there is no benefit to going beyond the maximum LA level of 28% FA in IF. To achieve the DHA levels found in BM, the addition of DHA to IF is necessary, which is in line with regulations in China and the EU. Virtually all intervention studies investigating LA levels and safety were conducted in Western countries in the absence of added DHA. Therefore, well-designed intervention trials in infants across the globe are required to obtain clarity about optimal and safe levels of LA and LA/ALA ratios in IF.

Human Milk Lipid Profiles around the World: A Systematic Review and Meta-Analysis

Reported breast milk lipid concentrations may vary with geographical region, postnatal age, and year of sample collection. In this review, we summarized data on the concentrations of total fat, total phospholipids, cholesterol, and fatty acids in human milk worldwide and their variation according to lactation stage, study area, and sample collection year. A systematic literature search was performed using the PubMed, Embase, Web of Science, and Medline databases for English-language papers and Wanfang and China National Knowledge Infrastructure databases for Chinese-language papers. A total of 186 studies evaluating the human milk lipid profiles were included. According to random-effects models based on worldwide data, the summarized means (95% CIs) as percentages of total fat were 42.2% (41.1%, 43.3%) for SFAs, 36.6% (35.6%, 37.5%) for MUFAs, and 21.0% (19.3%, 22.7%) for PUFAs. However, the study heterogeneity was high for most types of fatty acids (I2 > 99%). Human milk from Western countries had higher concentrations of MUFAs and 18:1n-9 (ω-9), but lower concentrations of PUFAs, 18:2n-6, 20:4n-6, 18:3n-3, 20:5n-3, 22:6n-3, and total n-6 PUFA compared with those from non-Western countries (P < 0.001-0.011). Significant lactation stage differences were observed for total fat and some individual fatty acids. The concentrations of SFAs and 16:0 were significantly negatively correlated with sampling year (P < 0.001-0.028). In contrast, a significant positive correlation between the concentrations of 18:2n-6 and 18:3n-3 and sampling year was observed (P < 0.001-0.035). Our results suggest that the pooling of data on human milk lipid profiles in different studies should be done with caution due to the high between-study heterogeneity. The concentration of lipids, including total fat, cholesterol, and specific fatty acids, differs in human milk according to lactation stage, geographical region, and year of sample collection.

Human milk fatty acid profile across lactational stages after term and preterm delivery: A pooled data analysis

BACKGROUND

Lipids in human milk (HM) provide the majority of energy for developing infants, as well as crucial essential fatty acids (FA). The FA composition of HM is highly variable and influenced by multiple factors. We sought to increase understanding of the variation in HMFA profiles and their development over the course of lactation, and after term and preterm delivery, using a pooled data analysis.

OBJECTIVE

To review the literature and perform a pooled data analysis to qualitatively describe an extensive FA profile (36 FAs) in term and preterm colostrum, transitional - and mature milk up to 60 days postpartum.

DESIGN

A Medline search was conducted for HMFA profile data following term or preterm delivery. The search was confined to English language papers published between January 1980 and August 2018. Studies reporting original data, extensive FA profiles in HM from healthy mothers were included. Weighted least squares (WLS) means were calculated from the pooled data using random or fixed effect models.

RESULTS

Our pooled data analysis included data from 55 studies worldwide, for a total of 4374 term milk samples and 1017 preterm milk samples, providing WLS means for 36 FAs. Patterns in both term and preterm milk were apparent throughout lactation for some FAs: The most abundant FAs (palmitic, linoleic and oleic acid) remained stable over time, whereas several long-chain polyunsaturated FAs (including ARA and DHA) seemed to decrease and short- and medium-chain FAs increased over time.

CONCLUSIONS

High heterogeneity between individual studies was observed for the reported levels of some FAs, whereas other FAs were remarkably consistent between studies. Our pooled data suggests that specific FA categories fluctuate according to distinct patterns over the course of lactation; many of these patterns are comparable between term and preterm milk.

The Concentration of Omega-3 Fatty Acids in Human Milk Is Related to Their Habitual but Not Current Intake

This study determined fatty acid (FA) concentrations in maternal milk and investigated the association between omega-3 fatty acid levels and their maternal current dietary intake (based on three-day dietary records) and habitual dietary intake (based on intake frequency of food products). Tested material comprised 32 samples of human milk, coming from exclusively breastfeeding women during their first month of lactation. Milk fatty acids were analyzed as fatty acid methyl ester (FAME) by gas chromatography using a Hewlett-Packard 6890 gas chromatograph with MS detector 5972A. We did not observe any correlation between current dietary intake of omega-3 FAs and their concentrations in human milk. However, we observed that the habitual intake of fatty fish affected omega-3 FA concentrations in human milk. Kendall’s rank correlation coefficients were 0.25 (p = 0.049) for DHA, 0.27 (p = 0.03) for EPA, and 0.28 (p = 0.02) for ALA. Beef consumption was negatively correlated with DHA concentrations in human milk (r = −0.25; p = 0.046). These findings suggest that current omega-3 FA intake does not translate directly into their concentration in human milk. On the contrary, their habitual intake seems to markedly influence their milk concentration.

An updated review of worldwide levels of docosahexaenoic and arachidonic acid in human breast milk by region

OBJECTIVE

We aimed to evaluate the DHA and arachidonic acid (AA) levels in human breast milk worldwide by country, region and socio-economic status.

DESIGN

Descriptive review conducted on English publications reporting breast-milk DHA and AA levels.

SETTING

We systematically searched and identified eligible literature in PubMed from January 1980 to July 2015. Data on breast-milk DHA and AA levels from women who had given birth to term infants were included.

SUBJECTS

Seventy-eight studies from forty-one countries were included with 4163 breast-milk samples of 3746 individuals.

RESULTS

Worldwide mean levels of DHA and AA in breast milk were 0·37 (sd 0·11) % and 0·55 (sd 0·14) % of total fatty acids, respectively. The breast-milk DHA levels from women with accessibility to marine foods were significantly higher than those from women without accessibility (0·35 (sd 0·20) % v. 0·25 (sd 0·14) %, P<0·05). Data from the Asian region showed the highest DHA concentration but much lower AA concentration in breast milk compared with all other regions, independent of accessibility to marine foods. Comparison was made among Canada, Poland and Japan - three typical countries (each with sample size of more than 100 women) from different regions but all with high income and similar accessibility to fish/marine foods.

CONCLUSIONS

The current review provides an update on worldwide variation in breast-milk DHA and AA levels and underlines the need for future population- or region-specific investigations.

Dietary Crude Lecithin Increases Systemic Availability of Dietary Docosahexaenoic Acid with Combined Intake in Rats

Crude lecithin, a mixture of mainly phospholipids, potentially helps to increase the systemic availability of dietary omega-3 polyunsaturated fatty acids (n-3 PUFA), such as docosahexaenoic acid (DHA). Nevertheless, no clear data exist on the effects of prolonged combined dietary supplementation of DHA and lecithin on RBC and plasma PUFA levels. In the current experiments, levels of DHA and choline, two dietary ingredients that enhance neuronal membrane formation and function, were determined in plasma and red blood cells (RBC) from rats after dietary supplementation of DHA-containing oils with and without concomitant dietary supplementation of crude lecithin for 2–3 weeks. The aim was to provide experimental evidence for the hypothesized additive effects of dietary lecithin (not containing any DHA) on top of dietary DHA on PUFA levels in plasma and RBC. Dietary supplementation of DHA-containing oils, either as vegetable algae oil or as fish oil, increased DHA, eicosapentaenoic acid (EPA), and total n-3 PUFA, and decreased total omega-6 PUFA levels in plasma and RBC, while dietary lecithin supplementation alone did not affect these levels. However, combined dietary supplementation of DHA and lecithin increased the changes induced by DHA supplementation alone. Animals receiving a lecithin-containing diet also had a higher plasma free choline concentration as compared to controls. In conclusion, dietary DHA-containing oils and crude lecithin have synergistic effects on increasing plasma and RBC n-3 PUFA levels, including DHA and EPA. By increasing the systemic availability of dietary DHA, dietary lecithin may increase the efficacy of DHA supplementation when their intake is combined.

Marine omega-3 phospholipids: metabolism and biological activities

The biological activities of omega-3 fatty acids (n-3 FAs) have been under extensive study for several decades. However, not much attention has been paid to differences of dietary forms, such as triglycerides (TGs) versus ethyl esters or phospholipids (PLs). New innovative marine raw materials, like krill and fish by-products, present n-3 FAs mainly in the PL form. With their increasing availability, new evidence has emerged on n-3 PL biological activities and differences to n-3 TGs. In this review, we describe the recently discovered nutritional properties of n-3 PLs on different parameters of metabolic syndrome and highlight their different metabolic bioavailability in comparison to other dietary forms of n-3 FAs.

Age dependent incorporation of 14C-DHA into rat brain and body tissues after dosing various 14C-DHA-esters

INTRODUCTION

The omega-3 fatty acid docosahexaenoic acid (DHA) accounts for 10% of fatty acids in human brain and is critical for neuronal function and brain development. Mechanisms of transport, accumulation and conservation of DHA in the brain are unclear. The objective of the study was to quantify the age dependent DHA incorporation into the brain of 2-, 4- or 10-week-old rats after a bolus dose of different DHA-esters.

METHODS

Rats were gavaged with (14)C-DHA-TAG, (14)C-DHA-PL or (14)C-DHA-TAG+PL at 2 mg DHA/kg BW. After 24h the distribution of radioactivity in body and brain regions was determined using quantitative whole body autoradiography (QWBA). Radiolabeled compounds were extracted from the brains to determine the identity of the radiolabeled compounds.

RESULTS

Accumulation of orally ingested (14)C-DHA in rat brain was less than 1% of the dose and decreased with age. Ester specific differences were seen only in 10-week-old rats, where oral (14)C-DHA-PL delivered a 2-fold higher accretion of radioactivity in the brain.

CONCLUSIONS

Less than 1% of a dietary achievable DHA dose reached the rat brain within 24h. Optimal efficacy of DHA-PL may occur in older age groups.

Milk Fat Globule structure & function; nanosciece comes to milk production

The biological process of fat globule assembly and secretion produces highly complex globule compositions and structures with many properties now recognized to be the direct result of these structures. During homogenization, fat globules are broken down and subsequently structures and surfaces different than the native state are formed. This process alters the milk fat globule unique macrostructure and the effects associated to their structure would be expected to be lost. In the present overview, the need for continued research of the fundamental aspects of the mechanism involved in milk fat globules synthesis secretion and size distribution, as well as establishing ways to regulate those processes are highlighted. Ultimately these insights will guide food technology to developing a new generation of structure based functional foods and as highlighted in this overview, dairy functional products should be the pioneering commodity.

Antineoplastic unsaturated fatty acids from Fijian macroalgae

Phytochemical analysis of Fijian populations of the green alga Tydemania expeditionis led to the isolation of two unsaturated fatty acids, 3(zeta)-hydroxy-octadeca-4(E),6(Z),15(Z)-trienoic acid (1) and 3(zeta)-hydroxy-hexadeca-4(E),6(Z)-dienoic acid (2), along with the known 3(zeta)-hydroxy-octadeca-4(E),6(Z)-dienoic acid (4). Investigations of the red alga Hydrolithon reinboldii led to identification of a glycolipid, lithonoside (3), and five known compounds, 15-tricosenoic acid, hexacosa-5,9-dienoic methyl ester, beta-sitosterol, 10(S)-hydroxypheophytin A, and 10(R)-hydroxypheophytin A. The structures of 1-3 were elucidated by spectroscopic methods (1D and 2D NMR spectroscopy and ESI-MS). Compounds 1, 2, and 4, containing conjugated double bonds, demonstrated moderate inhibitory activity against a panel of tumor cell lines (including breast, colon, lung, prostate and ovarian cells) with IC(50) values ranging from 1.3 to 14.4 microM. The similar cell selectivity patterns of these three compounds suggest that they might act by a common, but unknown, mechanism of action.

Docosahexaenoic and arachidonic acid concentrations in human breast milk worldwide

Concentrations of the long-chain polyunsaturated fatty acids (LCPUFAs) docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6) in human breast milk are important indicators of infant formula DHA and AA concentrations, and recent evidence suggests that neural maturation of breastfed infants is linked to breast-milk LCPUFA concentrations. We report a descriptive meta-analysis that considered 106 studies of human breast milk culled to include only studies that used modern analysis methods capable of making accurate estimates of fatty acid (FA) profiles and criteria related to the completeness of reporting. The final analysis included 65 studies of 2474 women. The mean (+/-SD) concentration of DHA in breast milk (by wt) is 0.32 +/- 0.22% (range: 0.06-1.4%) and that of AA is 0.47 +/- 0.13% (range: 0.24-1.0%), which indicates that the DHA concentration in breast milk is lower than and more variable than that of AA. The highest DHA concentrations were primarily in coastal populations and were associated with marine food consumption. The correlation between breast-milk DHA and AA concentrations was significant but low (r = 0.25, P = 0.02), which indicates that the mean ratio of DHA to AA in regional breast milk varies widely. This comprehensive analysis of breast-milk DHA and AA indicates a broad range of these nutrients worldwide and serves as a guide for infant feeding.