Polyunsaturated fatty acids and cytokine profiles: a clue to the changing prevalence of atopy?

Impact of Climate Change on Dietary Nutritional Quality and Implications for Asthma and Allergy

Asthma and allergic disorders are common in childhood with genetic and environmental determinants of disease that include prenatal nutritional exposures such as long-chain polyunsaturated fatty acids and antioxidants. Global climate change is implicated in asthma and allergic disorder morbidity with potential mechanisms including perturbations of ecosystems. There is support that environmental and climatic changes such as increasing global temperate and carbon dioxide levels affect aquatic and agricultural ecosystems with subsequent alterations in long-chain polyunsaturated fatty acid availability and nutrient quality and antioxidant capacity of certain crops, respectively. This article discusses asthma epidemiology and the influence of global climate change.

Long-Chain Polyunsaturated Fatty Acid Status at Birth and Development of Childhood Allergy: A Systematic Review

The associations of fetal fatty acids status to immune-related health parameters later in life are unclear. Our aim is to collect all available information on the relationship between fatty acid status at birth and allergy in childhood. Systematic literature search was performed on Ovid MEDLINE, Cochrane Library, and Embase. The search retrieved 897 articles without duplicates; 14 articles remained after excluding those that did not fit into our inclusion criteria. When the dichotomous parameter of suffering or not from allergic condition in childhood was analyzed, cord blood eicosapentaenoic acid (EPA) values proved to be significantly lower in allergic than non-allergic children in four comparisons from three studies. When the linear parameters of odds ratios and relative risks for allergy were taken into consideration, high cord blood EPA, but also high docosahexaenoic acid (DHA) and high total n-3 long-chain polyunsaturated fatty acid values were associated to clinically relevant reduction (at least 38%) in eight comparisons from five studies. Within the cord blood samples, higher EPA, docosapentaenoic acid, and DHA values were significantly and negatively associated in eight correlation analyses from three studies with laboratory parameters considered to reflect allergic trait. The data reported here may provide information for defining optimal fatty acid intakes for pregnant women.

Prenatal polyunsaturated fatty acids and child asthma: Effect modification by maternal asthma and child sex

BACKGROUND

Findings on prenatal polyunsaturated fatty acid (PUFA) intake and child wheeze and asthma have been inconsistent.

OBJECTIVE

We sought to examine associations between prenatal PUFA status and child wheeze/asthma and modifying effects of maternal asthma/atopy, child sex, and maternal race.

METHODS

Analyses included 1019 mother-child dyads with omega-3 (n-3) and omega-3 (n-6) PUFAs measured in second-trimester plasma; n-6/n-3 ratios were calculated. Child wheeze/asthma outcomes ascertained at age 4 to 6 years included ever physician-diagnosed asthma, current wheeze (symptoms past 12 months), current asthma (diagnosis and medication and/or symptoms past 12 months), and current diagnosed asthma. Each PUFA indicator and outcome was analyzed in separate models using modified Poisson regression with interaction terms.

RESULTS

In quartile (Q) analyses, higher n-6 PUFAs were associated with increased risk of ever (risk ratio [RR] high vs low [RR Q4 vs Q1], 1.70; 95% CI, 1.07-2.71) and current (RR Q4 vs Q1, 1.70; 95% CI, 1.07-2.71) diagnosed asthma, whereas n-3 PUFAs were associated with lower risk (RR Q4 vs Q1, 0.59; 95% CI, 0.33-1.03) of current diagnosed asthma (P_trend < .05 for all). Higher n-6 PUFAs were associated with a higher risk of all respiratory outcomes among children born to women with asthma (P_interaction < .05 for all outcomes). A significant 3-way interaction between child sex, maternal asthma, and n-6/n-3 PUFA indicated that male children born to women with asthma and a higher ratio had the highest risk across wheeze/asthma outcomes (P_interaction < .05).

CONCLUSIONS

Associations between prenatal PUFA status and childhood wheeze/asthma were modified by maternal history of asthma and child sex.

Diet and asthma in Lebanese schoolchildren: A cross-sectional study

OBJECTIVES

The causes of the global increase in asthma in children are unknown. It has been hypothesized that diet is an important factor that may play a role in the pathogenesis of the disease. The objective was to evaluate the association between diet and current asthma among Lebanese children.

METHODS

A cross-sectional study was conducted on 1000 children recruited from public and private schools in Lebanon. Of the total enrolled participants, 107 children were diagnosed with current asthma and were analyzed. The food frequency questionnaire was used to assess participants' dietary habits.

RESULTS

The consumption of sweets ≥3 times weekly (ORa = 5.42), white bread ≥3 times weekly (ORa = 26.38), and olive oil daily (ORa = 9.80) were associated with higher odds of current asthma. Drinking carbonated beverages occasionally (ORa = 0.25) and ≥3 times per week (ORa = 0.03) was significantly associated with lower odds of current asthma. Adhering to Mediterranean diet (occasional, >3 times weekly and daily) was significantly associated with lower odds of current asthma compared to never consuming Mediterranean diet (ORa = 0.23 and ORa = 0.22, respectively). The occasional consumption of bread was significantly associated with higher odds of current asthma (ORa = 8.2), whereas daily consumption was significantly associated with lower odds (ORa = 0.336). Moreover, the occasional, ≥3 times weekly and daily consumption of meat were significantly associated with higher odds of current asthma (ORa = 9.6; ORa = 5.1 and ORa = 4.5), respectively. An occasional consumption of junk food was significantly associated with lower odds of current asthma (ORa = 0.044), whereas a daily consumption was associated with higher odds.

CONCLUSION

Adhering to certain diets might be associated with higher odds of current asthma.

Maternal prenatal and/or postnatal n-3 long chain polyunsaturated fatty acids (LCPUFA) supplementation for preventing allergies in early childhood

BACKGROUND

Allergies have become more prevalent globally over the last 20 years. Dietary consumption of n-3 (or omega 3) long chain polyunsaturated fatty acids (LCPUFA) has declined over the same period of time. This, together with the known role of n-3 LCPUFA in inhibiting inflammation, has resulted in speculation that n-3 LCPUFA may prevent allergy development. Dietary n-3 fatty acids supplements may change the developing immune system of the newborn before allergic responses are established, particularly for those with a genetic predisposition to the production of the immunoglobulin E (IgE) antibody. Individuals with IgE-mediated allergies have both the signs and symptoms of the allergic disease and a positive skin prick test (SPT) to the allergen.

OBJECTIVES

To assess the effect of n-3 LCPUFA supplementation in pregnant and/or breastfeeding women on allergy outcomes (food allergy, atopic dermatitis (eczema), allergic rhinitis (hay fever) and asthma/wheeze) in their children.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (6 August 2014), PubMed (1966 to 01 August 2014), CINAHL via EBSCOhost (1984 to 01 August 2014), Scopus (1995 to 01 August 2014), Web of Knowledge (1864 to 01 August 2014) and ClinicalTrials.gov (01 August 2014) and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) evaluating the effect of n-3 LCPUFA supplementation of pregnant and/or lactating women (compared with placebo or no treatment) on allergy outcomes of the infants or children. Trials using a cross-over design and trials examining biochemical outcomes only were not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility and trial quality and performed data extraction. Where the review authors were also investigators on trials selected, an independent reviewer assessed trial quality and performed data extraction.

MAIN RESULTS

Eight trials involving 3366 women and their 3175 children were included in the review. In these trials, women were supplemented with n-3 LCPUFA during pregnancy (five trials), lactation (two trials) or both pregnancy and lactation (one trial). All trials randomly allocated women to either a n-3 LCPUFA supplement or a control group. The risk of bias varied across the eight included trials in this review with only two trials with a low risk of selection, performance and attrition bias.N-3 LCPUFA supplementation showed a clear reduction in the primary outcome of any allergy (medically diagnosed IgE mediated) in children aged 12 to 36 months (risk ratio (RR) 0.66, 95% confidence interval (CI) 0.44 to 0.98; two RCTs; 823 children), but not beyond 36 months (RR 0.86, 95% CI 0.61 to 1.20; one RCT, 706 children). For any allergy (medically diagnosed IgE mediated and/or parental report), no clear differences were seen in children either at 12 to 36 months (RR 0.89, 95% CI 0.71 to 1.11; two RCTs, 823 children) or beyond 36 months of age (RR 0.96, 95% CI 0.84 to 1.09; three RCTs, 1765 children).For the secondary outcomes of specific allergies there were no clear differences for food allergies at 12 to 36 months and beyond 36 months, but a clear reduction was seen for children in their first 12 months with n-3 LCPUFA (both for medically diagnosed IgE mediated and medically diagnosed IgE mediated and/or parental report). There was a clear reduction in medically diagnosed IgE-mediated eczema with n-3 LCPUFA for children 12 to 36 months of age, but not at any other time point for both medically diagnosed IgE mediated and medically diagnosed IgE mediated and/or parental report. No clear differences for allergic rhinitis or asthma/wheeze were seen at any time point for both medically diagnosed IgE mediated, and medically diagnosed IgE mediated and/or parental report.There was a clear reduction in children's sensitisation to egg and sensitisation to any allergen between 12 to 36 months of age when mothers were supplemented with n-3 LCPUFA.In terms of safety for the mother and child, n-3 LCPUFA supplementation during pregnancy did not show increased risk of postpartum haemorrhage or early childhood infections.

AUTHORS' CONCLUSIONS

Overall, there is limited evidence to support maternal n-3 LCPUFA supplementation during pregnancy and/or lactation for reducing allergic disease in children. Few differences in childhood allergic disease were seen between women who were supplemented with n-3 LCPUFA and those who were not.

Effects of dietary habits and risk factors on allergic rhinitis prevalence among Turkish adolescents

BACKGROUND

Allergic rhinitis (AR) is a global health problem affecting many people from childhood to adulthood. The aim of this study was to evaluate the prevalence of AR and related symptoms, and to assess the risk factors, dietary habits and the Mediterranean diet affecting AR.

METHODS

In a cross-sectional study design, 9991 children, aged 13-14 years in 61 primary schools in 32 districts of Istanbul were evaluated. The prevalence of AR symptoms among the children was evaluated using the ISAAC protocol.

RESULTS

In our study, total of 10,984 questionnaires were distributed to 13-14yr-old schoolchildren to 61 schools in 32 district of Istanbul and 9991 questionnaires were suitable for analysis with an overall response of 91.7%. The rates of lifetime rhinitis, rhinitis in last 12 months and lifetime doctor diagnosed AR prevalence were 53.5%, 38.3% and 4.5%, respectively. The variation among districts in the prevalence of doctor diagnosed AR was very high. The highest prevalence was about 10 times higher than in the district with the lowest prevalence (range: 1.4-14.5) of Istanbul. A family history of atopy, mother with a university degree, presence of cat at home during last 12 months and adenoidectomy were significant for increased doctor diagnosed AR risk. Additionally, although fish and other sea foods, fermented drinks made from millets and various seeds, animal fats and butter were independent risk factors for doctor diagnosed AR, fish oil and hamburger were protective foods for doctor diagnosed AR. The MD was not associated with the prevalence of doctor diagnosed AR.

CONCLUSIONS

This study shows that that there are wide variations for the prevalence of AR related symptoms in 13-14yr-old schoolchildren among districts of Istanbul in Turkey. Socio-economical, environmental factors, some dietary habits, but not Mediterranean diet may affect the prevalence of AR.

The impact of long-chain n-3 polyunsaturated fatty acids on human health

A considerable literature has been published on the health benefits of fish, oil-rich fish and fish oils and their constituent long-chain (LC) n-3 PUFA. Evidence from epidemiological studies highlights the cardioprotective attributes of diets rich in fish, especially oil-rich fish. Data from intervention trials are consistent in suggesting that LC n-3 PUFA lower the risk of CVD, probably by the multiple mechanisms of lowering serum triacylglycerols, improving the LDL:HDL ratio, anti-arrhythmic effects on heart muscle, improved plaque stability, anti-thrombotic effects and reduced endothelial activation. Research indicates LC n-3 PUFA provision has an impact during development, and there is preliminary evidence that docosahexaenoic acid supplementation during pregnancy could optimise brain and retina development in the infant. LC n-3 PUFA are also postulated to ameliorate behavioural and mental health disturbances such as depression, schizophrenia, dementia and attention deficit hyperactivity disorder. However, despite some positive evidence in each of these areas, use of LC n-3 PUFA in these conditions remains at the experimental stage. In the case of immune function, there is little doubt that LC n-3 PUFA have a positive effect. Although intervention trials in rheumatoid arthritis show strong evidence of benefit, evidence for efficacy in other inflammatory conditions, including Crohn's disease, ulcerative colitis, psoriasis, lupus, multiple sclerosis, cystic fibrosis and asthma, is inconsistent or inadequate. More promising evidence in some conditions may come from studies which attempt to modify the fetal environment using LC n-3 PUFA supplementation during pregnancy.

Novel challenges for the allergist

The last years have witnessed novel findings with exciting developments in the field of allergy-related diseases including asthma, bronchial hyperresponsiveness, eczema, and atopy that have enormously increased over the past few years. This issue of the Reviews is timely dedicated to comprehensive articles discussing the current trends in the study of these conditions. In particular, the impact of new data in genomics, environmental factors through epigenetics and proteomics will be reviewed and critically discussed.

Fish allergy in childhood

Fish and its derived products play an important role in human nutrition, but they may also be a potent food allergen. Fish can be an ingested, contact, and inhalant allergen. Gad c I, a Parvalbumin, the major allergen in codfish, is considered as fish and amphibian pan-allergen. Prevalence of fish allergy appears to depend on the amount of fish eaten in the local diet. In Europe, the highest consumption occurs in Scandinavian countries, Spain and Portugal. In Spain, fish is the third most frequent allergen in children under 2 yr of age after egg and cow's milk. An adverse reaction to fish may be of non-allergic origin, due to food contamination or newly formed toxic products, but the most frequent type of adverse reactions to fish are immunologic-mediated reactions (allergic reactions). Such allergic reactions may be both IgE-mediated and non-IgE-mediated. Most cases are IgE-mediated, due to ingestion or contact with fish or as a result of inhalation of cooking vapors. Some children develop non-IgE-mediated type allergies such as food protein induced enterocolitis syndrome. The clinical symptoms related to IgE-mediated fish allergy are most frequently acute urticaria and angioedema as well as mild oral symptoms, worsening of atopic dermatitis, respiratory symptoms such as rhinitis or asthma, and gastrointestinal symptoms such as nausea and vomiting. Anaphylaxis may also occur. Among all the species studied, those from the Tunidae and Xiphiidae families appear to be the least allergenic.

Fatty acids in cord blood plasma, the relation to soluble CD23 and subsequent atopy

Atopy is suggested to be linked to the balance between levels of n-6 and n-3 series of long chain polyunsaturated fatty acids (PUFAs) in the diet. In a nested case-control study, levels of fatty acids, IgE and soluble low affinity IgE receptor (sCD23) were measured in cord blood in 35 children who subsequently developed allergic sensitisation and atopic dermatitis before the age of 3, and similarly in 35 matched children without a history of atopy. We found a tendency to lower levels of the n-3 PUFAs eicosapentaenoic acid (EPA) and alpha-linolenic acid (ALA) in the cord blood plasma of atopics compared to non-atopics. Levels of sCD23 were negatively correlated to levels of n-3 series of PUFAs and n-9 eicosenoic acid, and levels of n-9 eicosenoic acid was negatively correlated to levels of IgE. There was no association between the levels of sCD23 and n-6 PUFAs. Lower levels of n-3 PUFAs in cord blood may be associated with the development of atopy in children. A possible mechanism may be through the regulation of CD23, thereby influencing IgE synthesis.

Limited effect of eicosapentaenoic acid on T-lymphocyte and natural killer cell numbers and functions in healthy young males

OBJECTIVE

Greatly increasing the amount of long-chain omega-3 polyunsaturated fatty acids in the diet has been reported in some studies to decrease T-lymphocyte and natural killer functions. However, dose-response relations have not been identified. The objective of this study was to determine the effect of supplementing the diet of young male subjects with different amounts of an oil rich in eicosapentaenoic acid (EPA) on T-lymphocyte proliferation, cytokine production by T lymphocytes, and natural killer cell activity.

METHODS

In a placebo-controlled, double-blind, parallel study, healthy young (18 to 42 y) males were randomized to one of four supplements. These were placebo (no additional omega-3 polyunsaturated fatty acids) or different amounts of an EPA-rich oil that provided 1.35, 2.7, or 4.05 g/d of EPA for 12 wk. Blood samples were taken at baseline and after 12 wk.

RESULTS

Eicosapentaenoic acid was incorporated in a linear dose-response fashion into mononuclear cell phospholipids. EPA did not alter the proportions of T lymphocytes, helper T lymphocytes, cytotoxic T lymphocytes, B lymphocytes, or natural killer cells in the bloodstream. T-lymphocyte proliferation in response to concanavalin A and the production of the cytokines interleukin-2, interferon-gamma, and interleukin-10 were not affected by the different treatments. However, interleukin-4 production was increased with increasing intake of EPA. Natural killer cell activity was little affected by the treatments, although there was a trend for EPA to increase activity at a low effector-to-target cell ratio.

CONCLUSION

T-lymphocyte and natural killer cell numbers and function in healthy young males are little affected by supplemental EPA intakes up to 4 g/d.

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.

Allergic sensitisation and allergic rhinitis are associated with n-3 polyunsaturated fatty acids in the diet and in red blood cell membranes

OBJECTIVE

Due to inconsistent results based on dietary intake data, unsaturated fatty acids in red blood cell (RBC) membranes and diet were used to investigate their association with allergic sensitisation and allergic rhinitis.

DESIGN

Cross-sectional, population-based study.

SETTING

Bavarian Nutrition Survey II (2002-03), Germany.

SUBJECTS

A total of 568 adult participants, 325 women and 243 men.

METHODS

By means of logistic regression models, the relation of fatty acids to (i) allergic sensitisation as defined by means of specific serum immunoglobulin E analysis (CAPSX1 class > or = 2), and (ii) self-reported allergic rhinitis was examined.

RESULTS

A high cell membrane level of eicosapentaenoic acid (EPA, 20:5 n-3) was inversely associated with allergic sensitisation, the adjusted odds ratio (OR) and 95% confidence interval (95% CI) were 0.52 (0.30-0.90) for the highest (vs lowest) quartile. A similar effect was observed for allergic rhinitis with an OR (95% CI) of 0.50 (0.24-1.03; P = 0.027 for trend). A higher dietary intake of alpha-linolenic acid (ALA, 18:3 n-3) was associated with a decreased risk of allergic sensitisation and allergic rhinitis with ORs (95% CIs) of 0.51 (0.28-0.93) and 0.43 (0.20-0.93), respectively, in the highest quartiles. No other dietary or cell membrane unsaturated fatty acid was significantly associated with the outcome variables, nor was the n-6/n-3 ratio. The strongest effects were observed among subjects under the age of 40 y.

CONCLUSIONS

In this cross-sectional study among adults, a high content of n-3 fatty acids in RBC membranes (EPA) or in the diet (ALA) is associated with a decreased risk of allergic sensitisation and allergic rhinitis.

Determinants of neonatal IgE level: parity, maternal age, birth season and perinatal essential fatty acid status in infants of atopic mothers

OBJECTIVE

The hygiene hypothesis suggests that the protective 'siblings effect' against atopic diseases such as atopic dermatitis, allergic asthma and hay fever is a result of recurrent infections during early childhood. A recent study and review have indicated that this protective effect may already arise in utero. Lower n-3 essential fatty acid (EFA) status is associated with increased parity, and EFA status has also been related to atopy. The present study confirms the negative association between parity and neonatal immunoglobulin E (IgE) levels and further unravel the role of perinatal EFA status.

METHODOLOGY

In a prospective cohort study in 184 atopic mothers and their neonates, we simultaneously measured serum total IgE and EFA levels in plasma phospholipids, both in the mother at 34-36 weeks of gestation and in the neonate at the age of 1 week. Linear regression analysis was used to estimate the effect of parity on maternal and neonatal IgE and EFA status, and the independent effects of parity and EFA status on IgE, controlling for confounding factors such as maternal age and birth season.

RESULTS

Parity was associated with lower neonatal IgE level (P < 0.01), as well as with lower docosahexanoic acid (DHA, 22:6n-3) status of the mother (P = 0.01) but not of the neonate (P > 0.69). In the multivariate analysis, higher parity, higher maternal IgE, lower maternal age and birth in the first 3 months of the year were independently associated with neonatal IgE level. No association was detected between maternal or neonatal EFA status and neonatal IgE.

CONCLUSIONS

As neonatal total serum IgE is predictive of later atopy, our results support the hypothesis that the sibling effect in atopy is already being programmed in utero. Our data also confirm earlier findings that DHA status is lower in multiparous women, but this did not confound the relation between parity and neonatal IgE.