Pia Lund

Visual acuity and erythrocyte docosahexaenoic acid status in breast-fed and formula-fed term infants during the first four months of life

It has been recognized that preterm infants have a more rapid development of visual acuity if fed human milk or a formula enriched with the long-chain polyunsaturated fatty acid (LCPUFA) docosahexaenoic acid (DHA) compared to a standard formula devoid of LCPUFA. Few studies have addressed whether the same is also true in term infants. The aim of the present study was to follow visual acuity and fatty acid composition in red blood cells (RBC) for the first 4 mon of life in 17 breast-fed and 16 formula-fed term infants. The formula used did not contain LCPUFA, but contained 1.7 wt% α-linolenic acid, and the linoleic/α-linolenic acid ratio was 8.5. The increase in visual acuity measured by Teller acuity cards developed more rapidly in breast-fed infants compared to formula-fed infants (P<0.001). This was parallelled by a decrease in DHA of RBC in formulafed infants, and with a significantly lower level at two and four months as compared to breast-fed infants. The content of DHA in milk from the breast-feeding mothers was high compared to other Western countries. The difference in visual acuity between the two feeding groups could be due to differences in DHA status as reflected by the RBC levels, but other explanations are possible. Intervention studies are required to verify if development of visual acuity in term formula-fed infants is dependent on the DHA level of formula.

Effect of Formula Supplemented with Docosahexaenoic Acid andγ-linolenic Acid on Fatty Acid Status and Visual Acuity in Term Infants

BACKGROUND Docosahexaenoic acid is present in high concentration in retina and does not influence visual development in preterm infants. It is still under discussion whether docosahexaenoic acid is important for visual development in term infants. METHODS Thirty-seven infants fed formula for a median of 14 days were randomized at median age of 25 days to three formulas: a) DHAGF: 0.3 wt% docosahexaenoic acid and 0.5 wt% gamma-linolenic acid; b) DHAF 0.3 wt% docosahexaenoic acid; or c) STF: standard formula without long-chain polyunsaturated fatty acids and 17 breast-fed infants were observed, using blood samples and anthropometric measurements from 1 to 4 months of age. At 4 months, visual acuity was measured by swept steady-state visual evoked potential. A cross-sectional study on 25 breast-fed infants was carried out as a reference group for the analyses. RESULTS Infants fed the two docosahexaenoic acid-supplemented formula had relative docosahexaenoic acid concentrations in red blood cell phospholipids almost as high as those in breast-fed infants, whereas infants in the standard formula group had significantly lower levels. The addition of gamma-linolenic acid to the formula had a positive effect on red blood cell arachidonic acid levels, compared with levels obtained using fish oil only. Visual acuity was significantly different among all feeding groups (analysis of variance; p = 0.05, means +/- standard deviation: breast-fed, 0.37+/-0.06 logMAR; DHAF and DHAGF combined, 0.40+/-0.07 logMAR; and standard formula 0.44+/-0.07 logMAR. However, there was no statistical difference among the formula groups. In a multiple regression analysis including all formula-fed infants, weight at delivery (p = 0.002), but not type of formula, was significantly associated with visual acuity at 4 months of age. CONCLUSIONS The addition of docosahexaenoic acid resulted in concentrations in red blood cells at similar levels as those in breast-fed infants, whereas the increase in visual acuity did not reach significance. The addition of gamma-linolenic acid resulted in higher arachidonic acid concentrations in red blood cells.

Conjugated Linoleic Acids Reduce Body Fat in Healthy Postmenopausal Women

Isomers of conjugated linoleic acids (CLA) reduce fat mass (FM) and increase insulin sensitivity in some, but not all, murine studies. In humans, this effect is still debatable. In this study, we compared the effect of 2 CLA supplements on total and regional FM assessed by dual energy X-ray absorptiometry, changes in serum insulin and glucose concentrations, and adipose tissue (AT) gene expression in humans. In a double-blind, parallel, 16-wk intervention, we randomized 81 healthy postmenopausal women to 1) 5.5 g/d of 40/40% of cis9,trans11-CLA (c9,t11-CLA) and trans10,cis12-CLA (t10,c12-CLA) (CLA-mix); 2) cis9, trans11-CLA (c9,t11-CLA); or 3) control (olive oil). We assessed all variables before and after the intervention. The CLA-mix group had less total FM (4%) and lower-body FM (7%) than the control (P = 0.02 and < 0.001, respectively). Post hoc analyses showed that serum insulin concentrations were greater in the CLA-mix group (34%) than the control group (P = 0.02) in the highest waist circumference tertile only. AT mRNA expression of glucose transporter 4, leptin, and lipoprotein lipase was lower, whereas expression of tumor necrosis factor-alpha was higher in the CLA-mix group than in the control group (P < 0.04). In conclusion, a 50:50 mixture of c9,t11- and t10,c12-CLA isomers resulted in less total and lower-body FM in postmenopausal women and greater serum insulin concentrations in the highest waist circumference tertile. Future research is needed to confirm the insulin desensitizing effect of the CLA mixture and the effect on the mRNA expression of adipocyte-specific genes in humans.

Effect of dietary fatty acids on the postprandial fatty acid composition of triacylglycerol-rich lipoproteins in healthy male subjects.

Objective: The aim of the present study was to investigate the effect of trans-18:1 isomers compared to other fatty acids, especially saturates, on the postprandial fatty acid composition of triacylglycerols (TAG) in chylomicrons and VLDL.Design: A randomised crossover experiment where five interesterified test fats with equal amounts of palmitic acid (P fat), stearic acid (S fat), trans-18:1 isomers (T fat), oleic acid (O fat), or linoleic acid (L fat) were tested.Subjects: A total of 16 healthy, normolipidaemic males (age 23±2 y) were recruited.Interventions: The participants ingested fat-rich test meals (1 g fat per kg body weight) and the fatty acid profiles of chylomicron and VLDL TAG were followed for 8 h.Results: The postprandial fatty acid composition of chylomicron TAG resembled that of the ingested fats. The fatty acids in chylomicron TAG were randomly distributed among the three positions in accordance with the distributions in test fats. Calculations of postprandial TAG concentrations from fatty acid data revealed increasing amounts up to 4 h but lower response curves (IAUC) for the two saturated fats in accordance with previous published data. The T fat gave results comparable to the O and L fats. The test fatty acids were much less reflected in VLDL TAG and there was no dietary influence on the response curves.Conclusions: The fatty acid composition in the test fats as well as the positional distributions of these were maintained in the chylomicrons. No specific clearing of chylomicron TAG was observed in relation to time.Sponsorship: Danish Research Development Program for Food Technology.

CD4+ T-cell activation is differentially modulated by bacteria-primed dendritic cells, but is generally down-regulated by n-3 polyunsaturated fatty acids

Appropriate activation of CD4+ T cells is fundamental for efficient initiation and progression of acquired immune responses. Here, we showed that CD4+ T‐cell activation is dependent on changes in membrane n‐3 polyunsaturated fatty acids (PUFAs) and is dynamically regulated by the type of signals provided by dendritic cells (DCs). Upon interaction with DCs primed by different concentrations and species of gut bacteria, CD4+ T cells were activated according to the type of DC stimulus. The levels of CD80 were found to correlate to the levels of expression of CD28 and to the proliferation of CD4+ T cells, while the presence of CD40 and CD86 on DCs inversely affected inducible costimulator (ICOS) and cytotoxic T‐lymphocyte antigen‐4 (CTLA‐4) levels in CD4+ T cells. For all DC stimuli, cells high in n‐3 PUFAs showed reduced ability to respond to CD28 stimulation, to proliferate, and to express ICOS and CTLA‐4. Diminished T‐cell receptor (TCR) and CD28 signalling was found to be responsible for n‐3 PUFA effects. Thus, the dietary fatty acid composition influences the overall level of CD4+ T‐cell activation induced by DCs, while the priming effect of the DC stimuli modulates CD80, CD86 and CD40 levels, thereby affecting and shaping activation of acquired immunity by differential regulation of proliferation and costimulatory molecule expression in CD4+ T cells.

Effects of butter oil blends with increased concentrations of stearic, oleic and linolenic acid on blood lipids in young adults

Objective: The aim of this present project was to evaluate a more satisfactory effect on plasma lipoprotein profile of spreads based on dairy fat.Design: This study was designed as a randomised cross-over experiment with a three-week treatment separated by a three-week wash-out period. Sixty five grams of the fat content of the habitual diets was replaced by either butter/grapeseed oil (90:10) (BG); butter oil and low erucic rapeseed oil (65:35) (BR) or butter blended in a 1:1 ratio with a interesterified mixture of rapeseed oil and fully hydrogenated rapeseed oil (70:30) (BS).Subjects: Thirteen healthy free-living young men (age 21–26 y) fulfilled the study.Interventions: At the beginning and end of each diet period two venous blood samples were collected. Triacylglycerol and cholesterol concentrations in total plasma and VLDL, LDL, IDL and HDL fractions were measured, as were apo A-1 and apo B concentrations. Fatty acid composition of plasma phospholipids, plasma cholesterol ester and platelets was also determined.Results: Significantly (P<0.05) lower total and LDL-cholesterol concentrations were observed after the BR and BS period, compared to BG. The effect of BR and BS did not differ. BG and BR resulted in equal concentrations of HDL-C, but significantly higher than BS. Consequently, a significantly lower LDL-C/HDL-C ratio was seen after the BR treatment compared to BG and BS. Apo A-1 concentrations were not significantly different, but Apo B was significantly increased after BG.Conclusions: Partially replacing milk fat with rapeseed oil seems to yield a more healthy spread. Stearic acid had a HDL-C lowering effect compared to milk fat, but did not affect LDL-C significantly. The addition of stearic acid did not improve the plasma lipoprotein profile for young men with low cholesterol levels.Sponsorship: Danish Food Research Programme (FØTEK I) and Danish Dairy Research Foundation.

Effect of randomization of mixtures of butter oil and vegetable oil on absorption and lipid metabolism in rats.

Background The nutritional effect of the regiospecific distribution of fatty acids in edible fats is currently discussed due to an increased use of interesterification of fats for human consumption. However, disagreeing results have been reported which may be due to the varying composition of the dietary fats compared. Data on the fate of such lipids beyond the bloodstream is rather scarce and animal model studies are needed. Aim of the study To compare the metabolism of butter oil and mixtures of butter and rapeseed oil, native or randomized, in a rat model. The regiospecific fatty acid distribution present in dietary fats was followed through absorption, chylomicron formation, and deposition in adipose tissue and in different liver lipids (triacylglycerols, phospholipids, and cholesterol esters). Methods Rats were fed for 6 weeks from weaning either butter oil (BO), a butteroil-rapeseed oil mixture 65:35 w/w (BR) or a randomized mixture of BR (tBR). Half of the animals were used for organ analysis, the rest for a postprandial study with the same fats and isolation of chylomicrons. The regiospecific distribution of the fatty acids present in the dietary fats was followed during metabolism by analyses of chylomicrons, depot fat and liver lipids, using regiospecific cleavage followed by TLC separation and quantification by GC. Results Randomization of edible fat mixtures leading to equal distribution of fatty acids between TG positions is directly reflected in the composition of chylomicrons. During clearing by lipoprotein lipase this positional distribution is abolished and the regiospecific composition of triacylglycerols in adipose tissue is completely identical for BR and tBR. Chylomicron remnants, which are taken up by the liver, are correspondingly fully degraded to free fatty acis by hepatic lipase, and distribution of fatty acids in liver triacylglycerols phospholipids and cholesterol esters are identical for the groups fed either BR or tBR. The group fed BO with a low content of linoleic acid is on the borderline of essential fatty acid-deficiency. Conclusion Randomization (interesterification) of butter oil with rapeseed oil (65:35 w/w) for use as edible fat did not have any impact on the fatty acid composition beyond the chylomicron step when compared to the native mixture.