Fish Oil Supplementation in Pregnancy Lowers F2-isoprostanes in Neonates at High Risk of Atopy

The effect of perinatal omega-3 fatty acid supplementation on inflammatory markers and allergic diseases: a systematic review

BACKGROUND

Maternal supplementation with omega-3 polyunsaturated fatty acids (n-3 PUFA) may modulate immune responses and allergy in neonates and children.

OBJECTIVE

To determine if n-3 PUFA supplementation during pregnancy and lactation reduces risk for childhood allergic disease.

SEARCH STRATEGY

We searched Medline and all evidence-based medicine reviews for randomised controlled trials comparing the effects of n-3 PUFA and placebo supplementation during pregnancy and/or lactation on childhood allergic diseases and inflammatory cytokines.

SELECTION CRITERIA

We included studies reporting on food allergy, response to the egg skin prick test (SPT), atopy and asthma in infancy and childhood as well as production of interleukin-13 and interferon-gamma, two cytokines involved in the pathogenesis of asthma. For assessment of inclusion, two authors reviewed all abstracts for suitability and independently extracted data.

DATA COLLECTION AND ANALYSIS

Two-by-two tables were constructed and odds ratios (OR) were calculated for the outcomes: response to the SPT, food allergy, atopy and asthma in childhood. The assays differed so data on inflammatory markers were reported in narrative form.

MAIN RESULTS

Five randomised controlled trials (n = 949) were included. n-3 PUFA supplementation during pregnancy reduced 12-month prevalence of positive egg SPT (two trials, 12/87 versus 32/100, OR 0.33, 95% CI 0.16, 0.70) and childhood asthma (two trials, 10/303 versus 17/179, OR 0.349, 95% CI 0.154, 0.788) and significantly reduced cord blood interleukin-13 levels. Supplementation during lactation did not prevent asthma, food allergy or atopy.

CONCLUSION

n-3 PUFA supplementation during pregnancy decreases childhood asthma and response to SPT.

The omega-3 fatty acids EPA and DHA decrease plasma F(2)-isoprostanes: Results from two placebo-controlled interventions

Omega-3 (omega3) fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), protect against cardiovascular disease. Despite these benefits, concern remains that omega3 fatty acids may increase lipid peroxidation. It has previously been shown that urinary F(2)-isoprostanes (F(2)-IsoPs) were reduced following omega3 fatty acid supplementation in humans. It is now determined whether EPA or DHA supplementation affects plasma F(2)-IsoPs. In two 6-week placebo-controlled interventions, Study A: overweight, dyslipidaemic men; and Study B: treated-hypertensive Type 2 diabetic, patients were randomized to 4 g daily EPA, DHA. Post-intervention plasma F(2)-IsoPs were significantly reduced by EPA (24% in Study A, 19% in Study B) and by DHA (14% in Study A, 23% in Study B) relative to the olive oil group. The fall in plasma F(2)-IsoPs was not altered in analyses that corrected for changes in plasma arachidonic acid, which was reduced with EPA and DHA supplementation. Neither F(3)- nor F(4)-IsoPs were observed in plasma in both studies. These results show that in humans, EPA and DHA reduce in vivo oxidant stress as measured in human plasma and urine.

Using isoprostanes as biomarkers of oxidative stress: some rarely considered issues

The measurement of F2-isoprostanes by methods utilizing mass spectrometry is widely regarded as the best currently available biomarker of lipid peroxidation. F2-isoprostanes and their metabolites can be measured accurately in plasma, urine, and other body fluids using mass spectrometric techniques, and detailed protocols have been published in several papers. However, many clinical studies and intervention studies with diets or supplements, have employed single "spot" measurements of F2-isoprostanes on either plasma/serum or urine to estimate "oxidative stress." This review examines the validity of the common assumption that plasma and urinary F2-isoprostane measurements are equivalent. It identifies scenarios where they may not be and where "spot" measurements can be misleading, with examples from the literature. We also discuss the controversial issue of whether and how F2-isoprostane levels in plasma should be standardized against lipids, and, if so, which lipids to use.

Parenteral lipid emulsions based on olive oil compared with soybean oil in preterm (<28 weeks' gestation) neonates: a randomised controlled trial

BACKGROUND

: New olive oil-based (OL) lipid emulsions (olive:soy oil = 4:1) have lower polyunsaturated fatty acid (PUFA) (20% vs 60%) and higher vitamin E content (an antioxidant) compared with traditional soybean oil (SO) emulsions.

OBJECTIVE

: Compare efficacy and safety of OL with SO emulsions in preterm neonates (<28 weeks) at high risk for oxidative stress.

PATIENTS AND METHODS

: Preterm neonates (gestation 23-<28 weeks) were randomised to receive OL or SO emulsion for 5 days using a standard protocol in a tertiary perinatal centre (King Edward Memorial Hospital for Women, Perth, Western Australia). Investigators and outcome assessors were masked to allocation. Plasma F2-isoprostanes (lipid peroxidation marker), plasma, and red blood cell fatty acids were measured before and after the study. Safety was monitored by liver function tests.

RESULTS

: Forty-four of 50 participants (OL-23, SO-21) completed the study. Both emulsions were well tolerated with no significant adverse events. F2-isoprostane levels were comparable at baseline and study end. Oleic and linoleic acid levels were significantly high on day 6 in OL and SO groups, respectively. Long-chain PUFA levels were similar between groups despite the lower PUFA content of OL. The olive oil-based group had significantly higher levels of C18:4n-3, suggesting Delta6-desaturase enzyme inhibition in the SO group.

CONCLUSIONS

: Olive oil-based emulsion was safe and well tolerated by preterm neonates. Similar long-chain PUFA levels were achieved in the OL group despite significantly lower amount of PUFA content; however, there was no difference in lipid peroxidation (F2-isoprostane levels). Large trials are needed to confirm these benefits.

Flaxseed oil supplementation increases plasma F1-phytoprostanes in healthy men

Supplementation with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been reported to reduce lipid peroxidation products formed from arachidonic acid (F(2)-isoprostanes) in healthy humans, as well as in those under oxidative stress. alpha-Linolenic acid (ALA) is a precursor to EPA and DHA; however, its conversion in humans is thought to be inefficient. ALA can also undergo free radical oxidation, forming compounds known as F(1)-phytoprostanes, which are found in all plants and are in high concentrations in plant pollens. In this study, we examined the effect of ALA supplementation on plasma and urine F(1)-phytoprostane and F(2)-isoprostane concentrations in men. Thirty-six nonsmoking men, aged 20-65 y, were recruited from the general population and randomly allocated to consume 9 g/d of either flaxseed oil (62% ALA, 5.4 g/d) or olive oil (placebo) for 4 wk in a parallel design. At baseline and after 4 wk of supplementation, blood samples and a 24-h urine sample were collected for measurement of plasma and urinary F(1)-phytoprostanes and F(2)-isoprostanes and plasma fatty acids. Compared with the olive oil group, plasma phospholipid ALA was greater (P < 0.0001), as were F(1)-phytoprostanes in plasma (P = 0.049) and urine (P = 0.06) in the flaxseed oil group after 4 wk supplementation. Flaxseed oil did not affect plasma or urinary F(2)-isoprostanes. The greater plasma F(1)-phytoprostane concentration in the flaxseed oil group most likely resulted from the increased plasma concentration of the ALA substrate and/or the F(1)-phytoprostane content of the flaxseed oil. Future studies are needed to determine the physiological importance of increased plasma and urine F(1)-phytoprostanes and their relevance to heart disease prevention.

Placental Tissue Levels of Nonesterified Polyunsaturated Fatty Acids in Normal and Preeclamptic Pregnancies

OBJECTIVE

We previously reported that maternal plasma levels of nonesterified polyunsaturated fatty acids were decreased in women with preeclampsia as compared to women with normal pregnancies. Polyunsaturated fatty acids of the n-6 and n-3 families are essential dietary fatty acids. The n-6 polyunsaturated fatty acids are involved in inflammatory reactions, whereas n-3 polyunsaturated fatty acids protect against inflammation.

METHODS

In this study, we investigated the composition of nonesterified polyunsaturated fatty acids in placental tissue of normal and preeclamptic pregnancies. Linoleic (18:2) and arachidonic (20:4, AA) acids of the n-6 family and linolenic (18:3), eicosapentaenoic (20:5, EPA) and docosahexaenoic (22:6, DHA) acids of the n-3 family were analyzed.

CONCLUSIONS

We found that total concentrations of nonesterified polyunsaturated fatty acids were lower in placental tissues from preeclamptic pregnancies than from normal pregnancies. Both n-6 and n-3 polyunsaturated fatty acids were decreased. The decrease in n-6 polyunsaturated fatty acids was due to a decrease in AA. The concentration of linoleic acid was not altered. For n-3 polyunsaturated fatty acids, DHA was decreased, with no change in linolenic acid. The percentage decrease in EPA and DHA was greater than for AA, so the ratio of n-6 to n-3 polyunsaturated fatty acids was two-fold higher in preeclampsia than normal pregnancy. Because the levels of essential fatty acids, linoleic (18:2) and linolenic (18:3), are preserved but levels of metabolites (AA and DHA) are reduced, we speculate that placental oxidative stress and increased conversion of AA to thromboxane are responsible for the decreased concentrations of polyunsaturated fatty acids in preeclampsia.

Effect of docosahexaenoic acid on oxidative stress in placental trophoblast cells

BACKGROUND

Docosahexaenoic acid (DHA) is an indispensable component of cell membranes that is required at high levels during pregnancy.

STUDY DESIGN

We investigated the effects of DHA (0 to 100 microM) in the placenta on oxidative stress using a trophoblast cell line, BeWo.

RESULTS

Oxidative stress levels (as evaluated using a fluorescent probe) and lipid peroxidation were significantly higher in cells preincubated with 100 microM of DHA. Oxidative DNA damage in cells preincubated with modest levels of DHA (1 or 10 microM) was significantly lower than for untreated cells or cells preincubated with 100 microM DHA. Survival rates of cells preincubated with modest levels of DHA after oxidative challenge (with H(2)O(2) or Xanthine plus Xanthine oxidase) were significantly higher than without DHA preincubation.

CONCLUSION

Modest levels of DHA alleviate oxidative DNA damage whereas high levels of DHA accelerate lipid peroxidation. Thus, DHA supplementation during pregnancy may exert oxidative or antioxidant properties via different mechanisms and depending on dosage.

Essential fatty acids and their metabolites could function as endogenous HMG-CoA reductase and ACE enzyme inhibitors, anti-arrhythmic, anti-hypertensive, anti-atherosclerotic, anti-inflammatory, cytoprotective, and cardioprotective molecules

Lowering plasma low density lipoprotein-cholesterol (LDL-C), blood pressure, homocysteine, and preventing platelet aggregation using a combination of a statin, three blood pressure lowering drugs such as a thiazide, a beta blocker, and an angiotensin converting enzyme (ACE) inhibitor each at half standard dose; folic acid; and aspirin-called as polypill- was estimated to reduce cardiovascular events by approximately 80%. Essential fatty acids (EFAs) and their long-chain metabolites: gamma-linolenic acid (GLA), dihomo-GLA (DGLA), arachidonic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) and other products such as prostaglandins E1 (PGE1), prostacyclin (PGI2), PGI3, lipoxins (LXs), resolvins, protectins including neuroprotectin D1 (NPD1) prevent platelet aggregation, lower blood pressure, have anti-arrhythmic action, reduce LDL-C, ameliorate the adverse actions of homocysteine, show anti-inflammatory actions, activate telomerase, and have cytoprotective properties. Thus, EFAs and their metabolites show all the classic actions expected of the "polypill". Unlike the proposed "polypill", EFAs are endogenous molecules present in almost all tissues, have no significant or few side effects, can be taken orally for long periods of time even by pregnant women, lactating mothers, and infants, children, and adults; and have been known to reduce the incidence cardiovascular diseases including stroke. In addition, various EFAs and their long-chain metabolites not only enhance nitric oxide generation but also react with nitric oxide to yield their respective nitroalkene derivatives that produce vascular relaxation, inhibit neutrophil degranulation and superoxide formation, inhibit platelet activation, and possess PPAR-gamma ligand activity and release NO, thus prevent platelet aggregation, thrombus formation, atherosclerosis, and cardiovascular diseases. Based on these evidences, I propose that a rational combination of omega-3 and omega-6 fatty acids and the co-factors that are necessary for their appropriate action/metabolism is as beneficial as that of the combined use of a statin, thiazide, a beta blocker, and an angiotensin converting enzyme (ACE) inhibitor, folic acid, and aspirin. Furthermore, appropriate combination of omega-3 and omega-6 fatty acids may even show additional benefits in the form of protection from depression, schizophrenia, Alzheimer's disease, and enhances cognitive function; and serve as endogenous anti-inflammatory molecules; and could be administered from childhood for life long.

F2-isoprostanes in human health and diseases: from molecular mechanisms to clinical implications

Oxidative stress is implicated as one of the major underlying mechanisms behind many acute and chronic diseases, and involved in normal aging. However, the measurement of free radicals or their end products is complicated. Thus, proof of association of free radicals in pathologic conditions has been absent. Isoprostanes are prostaglandin-like bioactive compounds that are biosynthesized in vivo independent of cyclooxygenases, principally through free-radical catalyzation of arachidonic acid. Isoprostanes are now considered to be reliable biomarkers of oxidative stress, as evidenced by an autonomous study organized recently by the National Institutes of Health (NIH) in the United States. A number of these compounds have potent biologic activities such as vasoconstrictive and certain inflammatory properties. Isoprostanes are involved in many human diseases. Additionally, elevated levels of F(2)-isoprostanes have been seen in normal human pregnancy and after intake of some fatty acids, but their physiologic assignments have not yet been distinctive. This evidence indicates that measurement of bioactive F(2)-isoprostanes in body fluids offers a unique noninvasive analytic utensil to study the role of free radicals in physiology, oxidative stress-related diseases, experimental acute or chronic inflammatory conditions, and also in the assessment of various antioxidants, radical scavengers, and drugs.

Fish oil intake compared with olive oil intake in late pregnancy and asthma in the offspring: 16 y of registry-based follow-up from a randomized controlled trial

BACKGROUND

Evidence suggests that asthma is rooted in the intrauterine environment and that intake of marine n-3 polyunsaturated fatty acids (n-3 PUFAs) in pregnancy may have immunomodulatory effects on the child.

OBJECTIVE

Our aim was to examine whether increasing maternal intake of n-3 PUFAs in pregnancy may affect offspring risk of asthma.

DESIGN

In 1990, a population-based sample of 533 women with normal pregnancies were randomly assigned 2:1:1 to receive four 1-g gelatin capsules/d with fish oil providing 2.7 g n-3 PUFAs (n = 266); four 1-g, similar-looking capsules/d with olive oil (n = 136); or no oil capsules (n = 131). Women were recruited and randomly assigned around gestation week 30 and asked to take capsules until delivery. Among 531 live-born children, 528 were identified in registries and 523 were still alive by August 2006. Diagnoses from the International Coding of Diseases version 10 were extracted from a mandatory registry that recorded diagnoses reported from hospital contacts.

RESULTS

During the 16 y that passed since childbirth, 19 children from the fish oil and olive oil groups had received an asthma-related diagnosis; 10 had received the diagnosis allergic asthma. The hazard rate of asthma was reduced by 63% (95% CI: 8%, 85%; P = 0.03), whereas the hazard rate of allergic asthma was reduced by 87% (95% CI: 40%, 97%; P = 0.01) in the fish oil compared with the olive oil group.

CONCLUSION

Under the assumption that intake of olive oil in the dose provided here was inert, our results support that increasing n-3 PUFAs in late pregnancy may carry an important prophylactic potential in relation to offspring asthma.

Impact of PUFA on early immune and fetal development

It has recently been reported that the increased prevalence in childhood allergy may be linked to deviations in fetal immune development. One reason may be impaired nutrient supply. Hence, a well-differentiated placenta together with an optimal fetal nutrition via the mother are important prerequisites for the establishment of a functional immune system with normal immune responses. Fatty acids and their derivatives can influence both the early immune development and immune maturation by regulating numerous metabolic processes and the gene expression of important proteins such as enzymes and cytokines. The present review summarises the impact of nutritional fatty acids on the development of the immune system as well as the fetal development. It describes the mechanisms of action of PUFA, trans fatty acids and conjugated linoleic acids in programming the fetus with regard to its risk of acquiring atopic diseases in childhood.

Maternal fish oil supplementation in pregnancy modifies neonatal leukotriene production by cord-blood-derived neutrophils

Fish oil supplementation has been shown to reduce neutrophil production of inflammatory LTB4 (leukotriene B4) in adults. The present study is the first to examine the effects on neonatal neutrophil function following supplementation in pregnancy. Pregnant women with allergic disease (n=98) were randomized to receive either fish oil [3.7 g of n-3 long-chain PUFAs (polyunsaturated fatty acids)/day] or a placebo supplement for the final 20 weeks of pregnancy. Leukotriene production by neonatal neutrophils was measured after stimulation with the calcium ionophore A23187. This was examined in relation to supplementation, cell membrane fatty acid levels and mononuclear cytokine production. Neutrophil LTB4 production was significantly reduced in neonates whose mothers had received fish oil in pregnancy. This was most evident for isomer 2 of LTB4 (P=0.031), although this was also observed for total LTB4 (P=0.051) and isomer 1 (P=0.088). There was also a trend for lower production of other PUFA metabolites, namely 5-HETE (5-hydroxyeicosatetraenoic acid; P=0.054) in the fish oil group. Accordingly, LTB4 levels were inversely related to membrane n-3 PUFA levels. Less inflammatory products (LTB5) were only produced at very low levels, although there was a trend for higher levels of this metabolite in the fish oil group. Consistent with this, LTB5 levels were positively correlated with n-3 PUFA membrane levels, particularly EPA (eicosapentanoic acid) and negatively correlated with n-6 PUFAs. Neonates with lower neutrophil LTB4 production also had lower production of pro-inflammatory IL (interleukin)-6 responses (r=0.35, P=0.005) and regulatory IL-10 responses (r=0.37, P=0.003) by LPS (lipopolysaccharide)-stimulated neonatal mononuclear cells. In conclusion, maternal dietary changes can modify neonatal neutrophil function. This has implications for the early immune programming, which can be influenced by the inflammatory milieu of local tissues during initial antigen encounter. It also provides evidence of another pathway through which long-chain PUFAs status can influence early immune development.

Maternal fish intake during pregnancy and atopy and asthma in infancy

BACKGROUND

There is growing evidence that n-3 fatty acids have anti-inflammatory properties and may modulate immune response. Dietary intake of these nutrients during pregnancy could play a role in the risk of asthma and atopy in the offspring.

METHODS

Using data from a cohort of women (n=462) enrolled during pregnancy and whose offspring were followed up to 6 years, we evaluated the impact of fish consumption during pregnancy on the incidence of atopy and asthma. Dietary intake was assessed by food frequency questionnaire (42 items) applied by an interviewer.

RESULTS

Thirty-four percent of infants had a medical diagnosis of eczema at age 1 year, 14.3% of the children were atopic [based on skin prick test (SPT) at 6 years], and 5.7% had atopic wheeze at age 6 years. After adjusting for potential confounding factors, fish intake during pregnancy was protective against the risk of eczema at age 1 year, a positive SPT for house dust mite at age 6 years and atopic wheeze at age 6 years [odds ratio (OR)=0.73 95% confidence interval (CI) 0.55-0.98, OR=0.68, 95% CI 0.46-1.01 and OR=0.55, 95% CI 0.31-0.96, respectively]. For an increase in fish intake from once per week to 2.5 times per week, the risk of eczema at age 1 year decreased by 37%, and the risk of positive SPT at age 6 years by 35%. Stratification by breastfeeding showed that fish intake was significantly related to a decrease risk in persistent wheeze among non-breastfed children (P for interaction<0.05). No protective effect was observed among breastfed children.

CONCLUSION

Our data suggest a protective effect of fish intake during pregnancy on the risk of atopy-related outcomes.

Prenatal fatty acid status and immune development: the pathways and the evidence

This review explores the effects of dietary long chain polyunsaturated fatty acids (LCPUFA) on various aspects of early immune development and their potential role in the development or the prevention of immune disease. Modern diets have become increasingly rich in n-6 LCPUFA and relatively n-3 LCPUFA deficient. These potentially "pro-inflammatory" dietary changes have clear implications for the immature and developing fetal immune system. It is now well known that immunological abnormalities precede the development of allergic disease and are frequently evident at birth or in the first months of life. This has lead to the hypothesis that potential effects of LCPUFA could be greatest in very early life before immune responses and clinical phenotype are established. Here we summarise the evidence that patterns of LCPUFA exposure in pregnancy can influence aspects of fetal immune in ways that are consistent with the immunological properties of these nutrients in adults. Specifically, human studies have shown that higher levels of n-3 LCPUFA are associated with reduction in neonatal oxidative stress, reduced production of inflammatory leukotienne B4 (LTB4) and altered T cell function. Inverse correlations between n-3 LCPUFA levels and neonatal T cell cytokine production, are consistent with adult studies showing reduction in T cell cytokine production with fish oil supplementation. At this stage the relevance of these effects in the prevention of disease is unclear. Although there have been no effects of postnatal fish oil supplementation (from 6 months of age) on allergy prevention, preliminary studies suggest possible merits in pregnancy and there are ongoing pregnancy intervention studies to address this more definitively.

In Vivo and in Vitro Lipid Peroxidation of Arachidonate Esters: The Effect of Fish Oil ω-3 Lipids on Product Distribution

The effect of lipid composition on the distribution of free radical oxidation products derived from arachidonic acid (20:4) esters has been studied in vitro and in vivo. Pro-inflammatory prostaglandin (PG) F2-like compounds, termed F2-isoprostanes (IsoPs), are produced in vivo and in vitro by the free radical-catalyzed peroxidation of arachidonic acid. Controlled free radical oxidation of mixtures of fatty acid esters in vitro showed that the formation of IsoPs from arachidonate is dramatically influenced by the presence of other fatty acid esters in the reaction mixture. Thus, three lipid mixtures containing the same arachidonate concentration but different amounts of other fatty esters (16:0; 18:1; 18:2; 20:5, and 22:6) were oxidized, and the product yields were determined by GC and LC/MS/MS analysis. The yield of F2-IsoP formed after 1 h of oxidation was 18% (based on arachidonate consumed) for mixtures containing arachidonate as the only oxidizable PUFA, but yields of these biologically active compounds dropped to 6% in polyunsaturated fatty acid (PUFA) mixtures typical of those found in tissues of fish oil-fed animals. F2-IsoP levels were also monitored in the livers of mice on diets supplemented with eicosapentaenoic acid (C20:5 omega-3; EPA), the PUFA most abundant in fish oil. While the level of arachidonic acid present in livers was not significantly different from that in control animals, levels of IsoPs in the liver were reduced in the EPA-fed mice compared to those in controls under conditions of oxidative stress (60 +/- 25% reduction, n = 5) or at baseline (48 +/- 14% reduction, n = 5). These results suggest that dietary omega-3 PUFAs may influence the formation of bio-active peroxidation products derived from omega-6 PUFAs by channeling the free radical pathway away from the F2-IsoPs.

Essential fatty acids: biochemistry, physiology and pathology

Essential fatty acids (EFAs), linoleic acid (LA), and alpha-linolenic acid (ALA) are essential for humans, and are freely available in the diet. Hence, EFA deficiency is extremely rare in humans. To derive the full benefits of EFAs, they need to be metabolized to their respective long-chain metabolites, i.e., dihomo-gamma-linolenic acid (DGLA), and arachidonic acid (AA) from LA; and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from ALA. Some of these long-chain metabolites not only form precursors to respective prostaglandins (PGs), thromboxanes (TXs), and leukotrienes (LTs), but also give rise to lipoxins (LXs) and resolvins that have potent anti-inflammatory actions. Furthermore, EFAs and their metabolites may function as endogenous angiotensin-converting enzyme and 3-hdroxy-3-methylglutaryl coenzyme A reductase inhibitors, nitric oxide (NO) enhancers, anti-hypertensives, and anti-atherosclerotic molecules. Recent studies revealed that EFAs react with NO to yield respective nitroalkene derivatives that exert cell-signaling actions via ligation and activation of peroxisome proliferator-activated receptors. The metabolism of EFAs is altered in several diseases such as obesity, hypertension, diabetes mellitus, coronary heart disease, schizophrenia, Alzheimer's disease, atherosclerosis, and cancer. Thus, EFAs and their derivatives have varied biological actions and seem to be involved in several physiological and pathological processes.

Fish consumption during the first year of life and development of allergic diseases during childhood

BACKGROUND

Fish consumption during infancy has been regarded as a risk factor for allergic disease but later evidence suggests a protective role. However, methodological limitations in the studies make conclusions uncertain. The aim of this study was to assess the association between fish consumption during the first year of life and development of allergic diseases by age 4.

METHODS

A prospective birth cohort of 4089 new-born infants was followed for 4 years using parental questionnaires at ages 2 months, 1, 2 and 4 years to collect information on exposure and health effects. The response rate at 4 years was 90%. A clinical investigation was performed at age 4 years, which included blood sampling for analysis of specific IgE to common food and airborne allergens.

RESULTS

Parental allergic disease and onset of eczema or wheeze during the first year of life delayed introduction of fish in the child's diet. After exclusion of such children to avoid disease-related modification of exposure, regular fish consumption during the first year of life was associated with a reduced risk for allergic disease by age 4, OR(adj) 0.76 (95% CI 0.61-0.94) and sensitization, OR(adj) 0.76 (0.58-1.0). The reduced risk appeared most pronounced for multiple disease, OR(adj) 0.56 (0.35-0.89). IgE-sensitization to fish was only present among 18 of the 2614 children.

CONCLUSION

Regular fish consumption before age 1 appears to be associated with a reduced risk of allergic disease and sensitization to food and inhalant allergens during the first 4 years of life.

Marine oil, and other prostaglandin precursor, supplementation for pregnancy uncomplicated by pre-eclampsia or intrauterine growth restriction

BACKGROUND

Population studies have shown that higher intakes of marine foods during pregnancy are associated with longer gestations, higher infant birthweights and a low incidence of pre-eclampsia. It is suggested that the fatty acids of marine foods may be the underlying cause of these associations.

OBJECTIVES

To estimate the effects of marine oil, and other prostaglandin precursor, supplementation during pregnancy on the risk of pre-eclampsia, preterm birth, low birthweight and small-for-gestational age.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (December 2005), The Cochrane Central Register of Controlled Trials (The Cochrane Library 2005, Issue 2) and MEDLINE (1966 to April 2005).

SELECTION CRITERIA

All randomised trials comparing oral marine oil, or other prostaglandin precursor, supplementation during pregnancy with either placebo or no treatment. Trials were excluded if their aim was to treat women with established pre-eclampsia or suspected intrauterine growth restriction.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, data extraction and trial quality.

MAIN RESULTS

Six trials, involving 2783 women, are included in this review. Three of these were rated as high quality, including the largest trial with 1477 women. Women allocated a marine oil supplement had a mean gestation that was 2.6 days longer than women allocated to placebo or no treatment (weighted mean difference (WMD), 2.55 days, 95% confidence interval (CI) 1.03 to 4.07 days; 3 trials, 1621 women). This was not reflected in a clear difference between the two groups in the relative risk (RR) of birth before 37 completed weeks, although women allocated marine oil did have a lower risk of giving birth before 34 completed weeks' gestation (RR 0.69, 95% CI 0.49 to 0.99; 2 trials, 860 women). Birthweight was slightly greater in infants born to women in the marine oil group compared with control (WMD 47 g, 95% CI 1 g to 93 g; 3 trials, 2440 women). However, there were no overall differences between the groups in the proportion of low birthweight or small-for-gestational age babies. There was no clear difference in the relative risk of pre-eclampsia between the two groups.

AUTHORS' CONCLUSIONS

There is not enough evidence to support the routine use of marine oil, or other prostaglandin precursor, supplements during pregnancy to reduce the risk of pre-eclampsia, preterm birth, low birthweight or small-for-gestational age.

Assessment of Tocopherol Metabolism and Oxidative Stress in Familial Hypobetalipoproteinemia

Background: Vitamin E supplementation has been recommended for persons with familial hypobetalipoproteinemia (FHBL), a rare disorder of lipoprotein metabolism that leads to low serum α-tocopherol and decreased LDL-cholesterol and apolipoprotein (apo) B. We examined the effect of truncated apoB variants on vitamin E metabolism and oxidative stress in persons with FHBL.

Methods: We studied 9 individuals with heterozygous FHBL [mean (SE) age, 40 (5) years; body mass index (BMI), 27 (10) kg/m2] and 7 normolipidemic controls [age, 41 (5) years; BMI, 25 (2) kg/m2]. We also studied 3 children—2 with homozygous FHBL (apoB-30.9) and 1 with abetalipoproteinemia—who were receiving α-tocopherol supplementation. We used HPLC with electrochemical detection to measure α- and γ-tocopherol in serum, erythrocytes, and platelets, and gas chromatography–mass spectrometry to measure F2-isoprostanes and tocopherol metabolites in urine as markers of oxidative stress and tocopherol intake, respectively.

Results: Compared with controls, persons with FHBL had significantly lower fasting plasma concentrations of total cholesterol [2.4 (0.2) vs 4.7 (0.2) mmol/L], triglycerides [0.5 (0.1) vs 0.9 (0.1) mmol/L], LDL-cholesterol [0.7 (0.1) vs 2.8 (0.3) mmol/L], apoB [0.23 (0.02) vs 0.84 (0.08) g/L], α-tocopherol [13.6 (1.0) vs 28.7 (1.4) μmol/L], and γ-tocopherol [1.0 (0.1) vs 1.8 (0.3) μmol/L] (all P &lt;0.03). Erythrocyte α-tocopherol was decreased [5.0 (0.2) vs 6.0 (0.3) μmol/L; P &lt;0.005], but we observed no differences in lipid-adjusted serum tocopherols, erythrocyte γ-tocopherol, platelet α- or γ-tocopherol, urinary F2-isoprostanes, or tocopherol metabolites.

Conclusion: Taken together, our findings do not support the recommendation that persons with heterozygous FHBL receive vitamin E supplementation.

Obesity and asthma, what are the links?

PURPOSE OF REVIEW

Obesity is a major cause of morbidity accounting for approximately 300 000 deaths each year and about 7% of the health care budget with an economic impact greater than US dollar 100 billion annually in the United States. Obesity and its sequelae such as cardiovascular disease, diabetes, arthritis or cancer have been on the rise over the last decades. The parallel time trend with an increasing prevalence of asthma has induced a lively debate about a potential link between both conditions.

RECENT FINDINGS

A number of prospective studies have shown that weight gain can antedate the development of asthma. Effect modification by sex may occur as some studies have shown effects of body mass index on asthma only among females. However, sex differences are not consistent. Several hypotheses have been proposed to explain the epidemiological associations including alterations in airway mechanics and immune responses, hormonal influences and genetic factors.

SUMMARY

There is evidence that obesity and overweight are associated with the development of asthma. Yet, the mechanisms underlying this relation are unclear. Weight reduction among asthmatic patients can result in improvements of lung function demonstrating the potential clinical impact of the findings.

Effect of fish and fish oil-derived omega-3 fatty acids on lipid oxidation

There is evidence that omega-3 (omega3) fatty acids derived from fish and fish oils reduce the risk of cardiovascular disease via mechanisms underlying atherosclerosis, thrombosis and inflammation. Despite these benefits, there has been concern that these fatty acids may increase lipid peroxidation. However, the in vivo data to date are inconclusive, due in part to limitations in the methodologies. In this regard, our findings using the measurement of F(2)-isoprostanes, a reliable measure of in vivo lipid peroxidation and oxidant stress, do not support adverse effects of omega3 fatty acids on lipid peroxidation.

N-3 fatty acids and pregnancy outcomes

PURPOSE OF REVIEW

To discuss new data from the literature on the relationship between the supply of n-3 polyunsaturated fatty acids during pregnancy and pregnancy outcomes, evaluated as the fatty acid composition of blood and breast milk, fetal and infantile development and maternal health.

RECENT FINDINGS

Supplementation of alpha-linolenic acid in high doses or docosahexaenoic acid in low doses did not result in a significant enhancement of the blood docosahexaenoic acid status of the offspring. In contrast, supplementation of docosahexaenoic acid in relatively high doses led to significant increases in infantile docosahexaenoic acid values and to a significant enhancement of breast milk docosahexaenoic acid content. Electroretinogram data obtained during the first week of life and pattern-reversal visual evoked potentials investigated at 50 and 66 weeks postconception were significantly associated with the docosahexaenoic acid status of the infant at birth. Children whose mothers received docosahexaenoic acid supplementation during pregnancy and lactation scored better in mental processing tests carried out at 4 years than children whose mothers received placebo.

SUMMARY

Beneficial health outcomes are more likely to result from supplementation with docosahexaenoic acid itself, rather than its precursor alpha-linolenic acid. Trials have shown that a higher maternal docosahexaenoic acid intake during pregnancy may be favourable for the visual and cognitive development of the offspring. The significant positive association between maternal docosahexaenoic acid intake during pregnancy and the children's mental processing scores at 4 years suggest that optimization of the docosahexaenoic acid status of expectant women may offer long-term developmental benefits to their children.

Omega-3 fatty acids and inflammation

Dietary omega-3 (n-3) fatty acids have a variety of anti-inflammatory and immune-modulating effects that may be of relevance to atherosclerosis and its clinical manifestations of myocardial infarction, sudden death, and stroke. The n-3 fatty acids that appear to be most potent in this respect are the long-chain polyunsaturates derived from marine oils, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and this review is restricted to these substances. A variety of biologic effects of EPA and DHA have been demonstrated from feeding studies with fish or fish oil supplements in humans and animals. These include effects on triglycerides, high-density lipoprotein cholesterol, platelet function, endothelial and vascular function, blood pressure, cardiac excitability, measures of oxidative stress, pro- and anti-inflammatory cytokines, and immune function. Epidemiologic studies provide evidence for a beneficial effect of n-3 fatty acids on manifestations of coronary heart disease and ischemic stroke, whereas randomized, controlled, clinical feeding trials support this, particularly with respect to sudden cardiac death in patients with established disease. Clinically important anti-inflammatory effects in man are further suggested by trials demonstrating benefits of n-3 fatty acids in rheumatoid arthritis, psoriasis, asthma, and inflammatory bowel disorders. Given the evidence relating progression of atherosclerosis to chronic inflammation, the n-3 fatty acids may play an important role via modulation of the inflammatory processes.