Early Introduction of Novel and Less-Studied Food Allergens in the Plant-Based Era: Considerations for US and EU Infant Formula Regulations.

Early life feeding practices may affect the long-term health of individuals, particularly in terms of the development of non-communicable diseases, such as metabolic and allergic diseases. Accumulating evidence suggests that the interplay of breastfeeding and/or formula feeding followed by the introduction of solids plays a role in the occurrence of non-communicable diseases both in the short and long term. International food allergy guidelines recommend that breastfeeding women do not need to avoid food allergens and do not recommend any infant formula for allergy prevention. Guidelines regarding solid food introduction for food allergy prevention recommend the introduction of well-cooked eggs and peanuts around 4-6 months of age, and not to delay the introduction of other food allergens. There is also an increasing trend to feed infants a plant-based or plant-forward diet and have access to infant formulas based on plant-based ingredients. The use of novel plant-based infant formulas raises a few questions reviewed in this paper: (1) Do fortified, plant-based infant formulas, compliant with US Food and Drug Administration (FDA) regulations and European Food Safety Authority (EFSA) (European) guidelines, support adequate infant growth? (2) Are plant-based infant formulas suitable for the management of cow's milk allergy? (3) Does feeding with novel, plant-based infant formulas increase the risk of food allergies to the food allergens they contain? (4) Does feeding infants plant-based food allergens in early life increase the risk of allergic and severe allergic reactions? The review of the literature indicated that (1) plant-based formulas supplemented with amino acids and micronutrients to comply with FDA regulations and EFSA guidelines, evaluated in sufficiently powered growth studies, can support adequate growth in infants; (2) currently available plant-based infant formulas are suitable for the management of CMA; (3) an early introduction and continuous intake of food allergens are more likely to prevent food allergies than to increase their risk; and (4) an early introduction of food allergens in young infants is safe.

Nutritional Strategies for the Prevention and Management of Cow's Milk Allergy in the Pediatric Age.

Cow's milk allergy (CMA) is one of the most common pediatric food allergies. The prevalence and severity of CMA have increased dramatically in the last decades, under the pressure of environmental factors in genetically predisposed individuals. Among the environmental influences, nutritional factors play a crucial role. Diet is the most modifiable factor, representing a potential target for the prevention and treatment of CMA. In this review, we report the most scientific-based nutritional strategies for preventing and managing pediatric CMA. In addition, we propose the most complete supplement of compounds able to prevent nutrient deficiencies in CMA pediatric patients and to positively influence the disease course.

Prevention of food allergy in infancy: the role of maternal interventions and exposures during pregnancy and lactation.

There is increased focus on the role of maternal interventions in the prevention of food allergy in infancy. There is no role for maternal dietary modifications during pregnancy or lactation, such as allergen avoidance, as a means of infant allergy prevention. Although exclusive breastfeeding is the recommended infant nutrition source globally, the effect of breastfeeding on infant allergy prevention remains unclear. There is emerging evidence that irregular cow's milk exposure (ie, infrequent formula supplementation) might increase the risk of cow's milk allergy. Although further studies are required, there is also emerging evidence that maternal peanut ingestion during breastfeeding along with early peanut introduction in infancy might have a preventive role. The effect of maternal dietary supplementation with vitamin D, omega-3, and prebiotics or probiotics remains unclear.

The role of milk feeds and other dietary supplementary interventions in preventing allergic disease in infants: Fact or fiction?

Exclusive breastfeeding ideally up to 6 months of life is the feed of choice for infants and should be promoted by healthcare professionals. However, when human milk is not sufficient or not available, infant formula, generally cow's milk-based, meeting strictly regulated nutritional and safety requirements, are recommended. Human breastmilk feeding has a positive health impact for both mother and child, but there is limited evidence that it has a long-term protective effect on the development of allergic disease. Some studies have found an association of an increased risk to develop cow's milk allergy with early exposure to cow's milk protein in formula milk. As a result, over the last 30 years, partially hydrolyzed formulas (pHF) have gained popularity and, more recently, become embroiled in a debate about their role in the primary prevention of allergic outcomes. Similar debates exist in regards to the potential preventative effects of pre-, pro- and synbiotics as well as nutritional factors, notably vitamin D and omega-3 fatty acids. This paper aims to critically address these aspects, drawing information from published data interpreted by an international expert group in paediatrics, allergy, gastro-intestinal diseases and nutrition. This group of experts emphasize that human milk is the optimal source of infant nutrition. With regards to pHFs, whilst no harm has been shown with their use and some studies have suggested potential benefit preventing atopic dermatitis in at risk infants, there is insufficient evidence for or against their routine recommendation for primary allergy prevention. The method of hydrolysation differs for every formula. There is insufficient evidence to recommend supplementation with vitamin D, omega-3 LCPUFA, specific prebiotic oligosaccharides or specific probiotic strains during pregnancy, lactation and early life to prevent the development of allergic disease in children. There remains a need for well-designed trials with the currently commercialised pHFs and supplements to allow for better clarity and evidence-based recommendations.

Hydrolyzed Rice Protein-Based Formulas, a Vegetal Alternative in Cow's Milk Allergy.

Formulas adapted to infant feeding, although most of the time made from cow's milk proteins, can be made from hydrolyzed rice protein but they must be classified as "formulas for specific medical needs", according to European regulations. The nutritional quality of rice proteins is thus suitable to be used in infant formulas giving that it is supplemented by certain amino acids which can be lacking. Besides, hydrolysis is required to facilitate their water solubility and digestibility. Owing to a low allergenicity of rice and to the absence of the cross-allergy between milk proteins and rice proteins, these formulas are adapted to the diet of children with cow's milk protein allergy (CMPA), which explains their growing use in some countries. However, CMPA, an expanding disorder, has consequences for growth, bone mineralization, and often has an association with allergy to other foods, including cow's milk extensive hydrolysate, so that a surveillance of the adaption of hydrolyzed rice protein formulas (HRPF) to CMPA, the absence of unexpected side effects, and the appropriate response to its various health hazards seems mandatory. This paper analyses the health problem deriving from CMPA, the industrial development of hydrolyzed rice protein formulas, and the limited number of clinical studies, which confirms, at the moment, a good allergic tolerance and safety. The goal is to better advise heath care professionals on their use of HRPFs during CMPA.

Milk-free diet followed by breastfeeding women.

BACKGROUND: Breastfeeding is the most common way of feeding infants. Human milk contains nutrients which are necessary to provide proper growth of a child. Nowadays there aren't any recommendations to follow elimination diet in order to decrease the risk of allergy or baby colic. Only the occurrence of health problems such as lactose intolerance or cow's milk protein allergy in breastfeeding mother or infant should be a reason for eliminating dairy products from diet. It seems to be important to explore the reasons and the frequency of following milk-free diet by breastfeeding women. OBJECTIVES: The main purpose of the study was to find the reasons for following milk-free diet by breastfeeding women and making an assessment of their nutrition knowledge and food habits. MATERIAL AND METHODS: Thirty-three breastfeeding women following milk-free diet took part in the project. The women were interviewed by the Computer Assisted Web Interview (CAWI) method with an original questionnaire. The results were developed with Spearman's rank correlation, Chi2 test and the gamma coefficient. The statistical significance level for the p-value was <0.05. RESULTS: The main reason for following milk-free diet by the breastfeeding women was the occurrence of hypersensitivity reactions of the children's gastrointestinal system after consuming milk by mother (72% responses). After excluding milk from diet only 42% respondents declared consuming new food products or dietary supplements in order to refill the potential deficiency of nutrients. The majority of respondents also eliminated from diet highly processed food products, fast-food and the carbonated drinks. The most often declared source of information about lactation was Internet (85%). Only 12% respondents asked a nutritionist in order to get the information about breastfeeding. CONCLUSIONS: It's necessary to promote a specific nutritional advice about following milk-free diet in breastfeeding women group in order to decrease the health risk connected with low calcium diet.

Preventing food allergy in infancy and childhood: Systematic review of randomised controlled trials.

BACKGROUND: This systematic review of ways to prevent immediate-onset/IgE-mediated food allergy will inform guidelines by the European Academy of Allergy and Immunology (EAACI). METHODS: The GRADE approach was used. Eleven databases were searched from 1946 to October 2019 for randomized controlled trials (and large prospective cohort studies in the case of breastfeeding). The studies included heterogeneous interventions, populations, and outcomes and so were summarized narratively. RESULTS: Forty-six studies examined interventions to reduce the risk of food allergy in infancy (up to 1 year) or early childhood. The following interventions for pregnant or breastfeeding women and/or infants may have little to no effect on preventing food allergy, but the evidence is very uncertain: dietary avoidance of food allergens, vitamin supplements, fish oil, probiotics, prebiotics, synbiotics, and emollients. Breastfeeding, hydrolyzed formulas, and avoiding cow's milk formula may not reduce the risk of cow's milk protein allergy; however, temporary supplementation with cow's milk formula in the first week of life may increase the risk of cow's milk allergy. Introducing well-cooked egg, but not pasteurized raw egg, from 4 to 6 months probably reduces the risk of hen's egg allergy. Introducing regular peanut consumption into the diet of an infant at increased risk beginning from 4 to 11 months probably results in a large reduction in peanut allergy in countries with a high prevalence. These conclusions about introducing peanut are based on moderate certainty evidence, from single trials in high-income countries. CONCLUSIONS: Sixty percent of the included studies were published in the last 10 years, but much still remains to be understood about preventing food allergy. In particular, there is a need to validate the potential benefits of early introduction of food allergens in a wider range of populations.

A free amino acid-based diet partially prevents symptoms of cow's milk allergy in mice after oral sensitization with whey.

BACKGROUND: Amino acid-based formulas (AAFs) are used for the dietary management of cow's milk allergy (CMA). Whether AAFs have the potential to prevent the development and/or symptoms of CMA is not known. OBJECTIVE: The present study evaluated the preventive effects of an amino acid (AA)-based diet on allergic sensitization and symptoms of CMA in mice and aimed to provide insight into the underlying mechanism. METHODS: C3H/HeOuJ mice were sensitized with whey protein or with phosphate-buffered saline as sham-sensitized control. Starting 2 weeks before sensitization, mice were fed with either a protein-based diet or an AA-based diet with an AA composition based on that of the AAF Neocate, a commercially available AAF prescribed for the dietary management of CMA. Upon challenge, allergic symptoms, mast cell degranulation, whey-specific immunoglobulin levels, and FoxP3+ cell counts in jejunum sections were assessed. RESULTS: Compared to mice fed with the protein-based diet, AA-fed mice had significantly lower acute allergic skin responses. Moreover, the AA-based diet prevented the whey-induced symptoms of anaphylaxis and drop in body temperature. Whereas the AA-based diet had no effect on the levels of serum IgE and mucosal mast cell protease-1 (mMCP-1), AA-fed mice had significantly lower serum IgG2a levels and tended to have lower IgG1 levels (P = .076). In addition, the AA-based diet prevented the whey-induced decrease in FoxP3+ cells. In sham-sensitized mice, no differences between the two diets were observed in any of the tested parameters. CONCLUSION: This study demonstrates that an AA-based diet can at least partially prevent allergic symptoms of CMA in mice. Differences in FoxP3+ cell counts and serum levels of IgG2a and IgG1 may suggest enhanced anti-inflammatory and tolerizing capacities in AA-fed mice. This, combined with the absence of effects in sham-sensitized mice indicates that AAFs for the prevention of food allergies may be an interesting concept that warrants further research.

Primary Prevention of Cow's Milk Sensitization and Food Allergy by Avoiding Supplementation With Cow's Milk Formula at Birth: A Randomized Clinical Trial.

Importance: Cow's milk formula (CMF) is used to supplement breastfeeding (BF) at birth without clear clinical evidence to support the practice. Objective: To determine whether avoiding supplementation with CMF at birth can decrease risks of sensitization to cow's milk protein and/or clinical food allergy, including cow's milk allergy (CMA), overall and in subgroups stratified by 25-hydroxyvitamin D (25[OH]D) levels. Design, Setting, and Participants: The Atopy Induced by Breastfeeding or Cow's Milk Formula (ABC) trial, a randomized, nonblinded clinical trial, began enrollment October 1, 2013, and completed follow-up May 31, 2018, at a single university hospital in Japan. Participants included 330 newborns at risk for atopy; of these, 312 were included in the analysis. Data were analyzed from September 1 through October 31, 2018. Interventions: Immediately after birth, newborns were randomized (1:1 ratio) to BF with or without amino acid-based elemental formula (EF) for at least the first 3 days of life (BF/EF group) or BF supplemented with CMF (≥5 mL/d) from the first day of life to 5 months of age (BF plus CMF group). Main Outcomes and Measures: The primary outcome was sensitization to cow's milk (IgE level, ≥0.35 allergen units [UA]/mL) at the infant's second birthday. Secondary outcomes were immediate and anaphylactic types of food allergy, including CMA, diagnosed by oral food challenge test or triggered by food ingestion, with food-specific IgE levels of at least 0.35 UA/mL. Subgroup analysis was prespecified by tertiles of serum 25(OH)D levels at 5 months of age. Results: Of the 312 infants included in the analysis (160 female [51.3%] and 152 male [48.7%]), 151 of 156 (96.8%) in the BF/EF and BF plus CMF groups were followed up until their second birthday. The primary outcome occurred in 24 infants (16.8%) in the BF/EF group, which was significantly fewer than the 46 infants (32.2%) in the BF plus CMF group (relative risk [RR], 0.52; 95% CI, 0.34-0.81). The middle tertile of the 25(OH)D subgroup, but not the low and high tertiles, had a significant interaction with the intervention (RR, 0.19; 95% CI, 0.07-0.50; P = .02). The prevalence of food allergy at the second birthday was significantly lower in the BF/EF than in the BF plus CMF groups for immediate (4 [2.6%] vs 20 [13.2%]; RR, 0.20; 95% CI, 0.07-0.57) and anaphylactic (1 [0.7%] vs 13 [8.6%]; RR, 0.08; 95% CI, 0.01-0.58) types. Conclusions and Relevance: The evidence suggests that sensitization to cow's milk and food allergy, including CMA and anaphylaxis, are primarily preventable by avoiding CMF supplementation for at least the first 3 days of life. Trial Registration: http://umin.ac.jp Identifier: UMIN000011577.

Oral exposure to the free amino acid glycine inhibits the acute allergic response in a model of cow's milk allergy in mice.

The conditionally essential amino acid glycine functions as inhibitory neurotransmitter in the mammalian central nervous system. Moreover, it has been shown to act as an anti-inflammatory compound in animal models of ischemic perfusion, post-operative inflammation, periodontal disease, arthritis and obesity. Glycine acts by binding to a glycine-gated chloride channel, which has been demonstrated on neurons and immune cells, including macrophages, polymorphonuclear neutrophils and lymphocytes. The present study aims to evaluate the effect of glycine on allergy development in a cow's milk allergy model. To this end, C3H/HeOuJ female mice were supplemented with glycine by oral gavage (50 or 100 mg/mouse) 4 hours prior to sensitization with cow's milk whey protein, using cholera toxin as adjuvant. Acute allergic skin responses and anaphylaxis were assessed after intradermal allergen challenge in the ears. Mouse mast cell protease-1 (mMCP-1) and whey specific IgE levels were detected in blood collected 30 minutes after an oral allergen challenge. Jejunum was dissected and evaluated for the presence of mMCP-1-positive cells by immunohistochemistry. Intake of glycine significantly inhibited allergy development in a concentration dependent manner as indicated by a reduction in; acute allergic skin response, anaphylaxis, serum mMCP-1 and serum levels of whey specific IgE. In addition, in-vitro experiments using rat basophilic leukemia cells (RBL), showed that free glycine inhibited cytokine release but not cellular degranulation. These findings support the hypothesis that the onset of cow's milk allergy is prevented by the oral intake of the amino acid glycine. An adequate intake of glycine might be important in the improvement of tolerance against whey allergy or protection against (whey-induced) allergy development.

Food Allergy Prevention and Treatment by Targeted Nutrition.

In view of the dramatic rise in the prevalence of food allergy globally, effective prevention strategies have become a public health priority. Several models have emerged around the etiology of food allergy, including the hygiene hypothesis, dual allergen exposure hypothesis, and vitamin D hypothesis. These form the basis for current and potential prevention strategies. Breastfeeding remains a key pillar of primary allergy prevention. Other nutritional interventions, including the use of whey-based, partially hydrolyzed formula in non-breastfed infants, also play an important role. In recent years, there has been a shift away from prolonged food allergen avoidance to the proactive allergen introduction from 4 months of age. This approach is supported by 2 pivotal randomized clinical trials showing that the early introduction of peanut and other food allergens significantly reduces the risk of food allergy. However, the implementation of this strategy at the population level still raises significant logistic problems, including patient selection and development of suitable food formats for young infants. Other prevention strategies, including vitamin D supplementation, are currently under evaluation. Maternal elimination diets during pregnancy and lactation are not recommended for allergy prevention. The treatment of food allergies has also seen major transformations. While strict allergen avoidance is still the key treatment principle, there is a greater focus on desensitization and tolerance induction by oral and epicutaneous immunotherapy. In addition, specialized hypoallergenic infant formulas for the treatment of infants with cow's milk allergy have undergone reformulation, including the addition of lactose and probiotics in order to modulate the gut microbiome and early immune responses. Further research is needed to inform the most effective food allergy prevention strategies at the population level. In addition, the wider application of food allergen immunotherapy may provide better health outcomes and improved quality of life for families affected by food allergies.

Partially hydrolyzed whey proteins prevent clinical symptoms in a cow's milk allergy mouse model and enhance regulatory T and B cell frequencies.

SCOPE: Partially hydrolyzed cow's milk proteins are used to prevent cow's milk allergy in children. Here we studied the immunomodulatory mechanisms of partial cow's milk hydrolysates in vivo. METHODS AND RESULTS: Mice were sensitized with whey or partially hydrolyzed whey using cholera toxin. Whey-specific IgE levels were measured to determine sensitization and immune cell populations from spleen, mesenteric lymph nodes and Peyer's patches after oral whey administration were measured by flowcytometry. Whey-specific IgE and IgG1 levels in partial whey hydrolysate sensitized animals were enhanced, but challenge did not induce clinical symptoms. This immunomodulatory effect of partial whey hydrolysate was associated with increased regulatory B and T cells in the spleen, together with a prevention of IgM-IgA class switching in the mesenteric lymph nodes and an increased Th1 and activated Th17 in the Peyer's patches. CONCLUSION: Partial hydrolysate sensitization did not induce whey-induced clinical symptoms, even though sensitization was established. Increased regulatory cell populations in the systemic immune system and a prevention of increased total Th1 and activated Th17 in the intestinal immune organs could contribute to the suppression of allergic symptoms. This knowledge is important for a better understanding of the beneficial effects of hydrolysates.

Prebiotic-supplemented partially hydrolysed cow's milk formula for the prevention of eczema in high-risk infants: a randomized controlled trial.

BACKGROUND: Prevention guidelines for infants at high risk of allergic disease recommend hydrolysed formula if formula is introduced before 6 months, but evidence is mixed. Adding specific oligosaccharides may improve outcomes. OBJECTIVE: To evaluate whether partially hydrolysed whey formula containing oligosaccharides (0.8 g/100 ml) (pHF-OS) can prevent eczema in high-risk infants [ISRCTN65195597]. METHODS: We conducted a parallel-group, multicentre, randomized double-blind controlled trial of pHF-OS vs standard cow's milk formula. Infants with a family history of allergic disease were randomized (stratified by centre/maternal allergy) to active (n = 432) or control (n = 431) formula until 6 months of age if formula was introduced before 18 weeks. Primary outcome was cumulative incidence of eczema by 12 months in infants randomized at 0-4 weeks (375 pHF-OS, 383 control). Secondary outcomes were cumulative incidence of eczema by 12 or 18 months in all infants randomized, immune markers at 6 months and adverse events. RESULTS: Eczema occurred by 12 months in 84/293 (28.7%) infants allocated to pHF-OS at 0-4 weeks of age, vs 93/324 (28.7%) control (OR 0.98 95% CI 0.68, 1.40; P = 0.90), and 107/347 (30.8%) pHF-OS vs 112/370 (30.3%) control in all infants randomized (OR 0.99 95% CI 0.71, 1.37; P = 0.94). pHF-OS did not change most immune markers including total/specific IgE; however, pHF-OS reduced cow's milk-specific IgG1 (P < 0.0001) and increased regulatory T-cell and plasmacytoid dendritic cell percentages. There was no group difference in adverse events. CONCLUSION: pHF-OS does not prevent eczema in the first year in high-risk infants. The immunological changes found require confirmation in a separate cohort.

DHA-rich tuna oil effectively suppresses allergic symptoms in mice allergic to whey or peanut.

BACKGROUND: Supplementation with long-chain n-3 polyunsaturated fatty acids (LCPUFAs) has been found to reduce the development of allergic disease. OBJECTIVE: The aim of this study was to compare the effectiveness of fish oil diets rich in eicosapentaenoic acid (20:5n-3; EPA) or docosahexaenoic acid (22:6n-3; DHA) in suppressing food allergic symptoms. METHODS: Mice were fed a control diet (10% soybean oil) or fish oil diet rich in EPA (4% soybean oil + 6% EPA oil containing 28.8% EPA and 13.7% DHA) or DHA (4% soybean oil + 6% DHA oil containing 7% EPA and 27.8% DHA), starting 14 d before and for 5 wk during oral sensitization with peanut extract (PE) or whey. Acute allergic skin responses, serum immunoglobulins (Igs), and mucosal mast cell protease-1 (mmcp-1) were assessed. Hyperimmune serum was transferred to naive recipient mice fed the different diets. RESULTS: The DHA diet effectively reduced the acute allergic skin response compared with the control or EPA diet in PE-allergic mice (control, 159 ± 15, or EPA, 129 ± 8, vs. DHA, 78 ± 7 µm; P < 0.0001 or P < 0.05, respectively). In contrast, both the DHA and EPA diets reduced the allergic skin response in whey allergic mice (control, 169 ± 9, vs. DHA, 91 ± 13, or EPA, 106 ± 14 µm; P < 0.001 or P < 0.01, respectively); however, only the DHA diet reduced mmcp-1 and whey-specific IgE and IgG1. The DHA and EPA diets also reduced the acute skin response in passively immunized mice. CONCLUSIONS: The DHA-rich fish oil diet reduced allergic sensitization to whey and allergic symptoms in both PE- and whey-allergic mice. These data suggest that DHA-rich fish oil is useful as an intervention to prevent or treat food allergy symptoms.

Preventing atopy and allergic disease.

Due to the recent exponential increase in food allergies and atopic disorders, effective allergy prevention has become a public health priority in many developed regions. Important preventive strategies include the promotion of breastfeeding and vaginal deliveries, judicious use of perinatal antibiotics, as well as the avoidance of maternal tobacco smoking. Breastfeeding for at least 6 months and introduction of complementary solids from 4-6 months are generally recommended. Complex oligosaccharides in breast milk support the establishment of bifidobacteria in the neonatal gut which stimulate regulatory T lymphocyte responses and enhance tolerance development. Maternal elimination diets during pregnancy or lactation are not effective in preventing allergies. If exclusive breastfeeding is not possible, (supplemental) feeding with a partially hydrolyzed whey-based formula or extensively hydrolyzed casein-based formula may reduce the risk of cow's milk allergy and atopic dermatitis in infants with a family history of atopy. By contrast, asthma and allergic rhinitis at 4-6 years of age are not prevented by this approach. Soy formula and amino acid-based formula have no proven role in allergy prevention. Perinatal supplementation with probiotics and/or prebiotics may reduce the risk of atopic dermatitis, but no reliable effect on the prevention of food allergy or respiratory allergies has so far been found. A randomized trial on maternal fish oil supplementation during pregnancy found that atopic dermatitis and egg sensitization in the first year of life were significantly reduced, but no preventive effect for food allergies was demonstrated. The role of vitamin D deficiency or excess as a risk factor for food allergy and atopic disorders requires further study.

Effects of supplementing different ratios of omega-3 and omega-6 fatty acids in western-style diets on cow's milk protein allergy in a mouse model.

SCOPE: This study investigated the effects of supplementing different ratios of omega-6 and omega-3 fatty acids (O6H = 10:1, O3O6 = 4:1, and O3H = 1:4) to western-style diets on cow ß-lactoglobulin (BLG) induced allergic reactions in Balb/c mice. METHODS AND RESULTS: Three-week-old mice were randomly assigned to three diet groups (n = 20/group). At 9 wk of age, half of the mice from each dietary treatment (n = 10) were intraperitoneally (i.p.) sensitized with three weekly doses of BLG and alum while the remaining half from each group was sham sensitized (controls). One week after the final sensitization, all mice were orally challenged with BLG. Elevated BLG-specific serum Igs were observed in all sensitized and challenged mice. IFN-γ, MCP-1, and IL-12p40 concentrations from lymphocytes of mesenteric lymph nodes were highest in O3H mice, compared to O3O6 and O6H mice. O6H mice had the highest IL-4 concentrations from splenic lymphocytes and a significantly lower rectal temperature after the challenge in comparison to O3O6 and O3H mice. CONCLUSIONS: Our results suggest that the ω-3 PUFA rich diets alleviated the severity of allergic reactions, and may modulate immune response toward T helper cell (Th)1-favoured immune response while the ω-6 PUFA rich diet exhibited no allergy alleviation with a stronger Th2 polarized immune response.

Dietary long chain n-3 polyunsaturated fatty acids prevent allergic sensitization to cow's milk protein in mice.

BACKGROUND: Cow's milk allergy is one of the most common food allergies in children and no treatment is available. Dietary lipid composition may affect the susceptibility to develop allergic disease. OBJECTIVE: Assess whether dietary supplementation with long chain n-3 polyunsaturated fatty acids (n-3 LCPUFA) prevents the establishment of food allergy. METHODS: Mice were fed a control or fish oil diet before and during oral sensitization with whey. Acute allergic skin response, serum immunoglobulins as well as dendritic cell (DC) and T cell subsets in mesenteric lymph nodes (MLN), spleen and/or small intestine were assessed. RESULTS: The acute allergic skin response was reduced by more than 50% in sensitized mice fed the fish oil diet compared to the control diet. In addition, anti-whey-IgE and anti-whey-IgG1 levels were decreased in the fish oil group. Serum transfer confirmed that the Th2-type humoral response was suppressed since sera of fish oil fed sensitized mice had a diminished capacity to induce an allergic effector response in naïve recipient mice compared to control sera. Furthermore, the acute skin response was diminished upon passive sensitization in fish oil fed naïve recipient mice. In addition, the percentage of activated Th1 cells was reduced by fish oil in spleen and MLN of sham mice. The percentage of activated Th2 cells was reduced in both sham- and whey-sensitized mice. In contrast, whey-sensitized mice showed an increased percentage of CD11b+CD103+CD8α- DC in MLN in association with enhanced FoxP3+ regulatory T cells (Treg) in spleen and intestine of fish oil fed whey-sensitized mice compared to sham mice. CONCLUSIONS AND CLINICAL RELEVANCE: Dietary n-3 LCPUFA largely prevented allergic sensitization in a murine model for cow's milk allergy by suppressing the humoral response, enhancing local intestinal and systemic Treg and reducing acute allergic symptoms, suggesting future applications for the primary prevention of food allergy.

CD25+ regulatory T cells transfer n-3 long chain polyunsaturated fatty acids-induced tolerance in mice allergic to cow's milk protein.

BACKGROUND: Recently, we have shown that dietary long-chain n-3 polyunsaturated fatty acids (n-3 LCPUFA) largely prevent allergic sensitization in a murine model for cow's milk allergy. The aim of this study was to assess the contribution of regulatory T cells (Treg) in the prevention of food allergy by n-3 LCPUFA. METHODS: C3H/HeOuJ female donor mice were fed a control or fish oil diet before and during oral sensitization with cow's milk protein whey. Acute allergic skin response (ASR), anaphylaxis, body temperature, serum immunoglobulins, and mouse mast cell protease-1 (mmcp-1) were assessed. Splenocytes of sham- or whey-sensitized donor mice fed either control or fish oil diet were adoptively transferred to naïve recipient mice. Recipient mice received a whole splenocyte suspension, splenocytes ex vivo depleted of CD25+ cells, or MACS-isolated CD4+ CD25+ Treg. Recipient mice were sham- or whey-sensitized and fed control diet. RESULTS: The ASR as well as whey-specific IgE and whey-specific IgG1 levels were reduced in whey-sensitized donor mice fed the fish oil diet as compared to the control diet. Splenocytes of control-diet-fed whey-sensitized donors transferred immunologic memory. By contrast, splenocytes of fish-oil-fed whey-sensitized - but not sham-sensitized - donors transferred tolerance to recipients as shown by a reduction in ASR and serum mmcp-1, and depletion of CD25+ Treg abrogated this. Transfer of CD25+ Treg confirmed the involvement of Treg in the suppression of allergic sensitization. CONCLUSIONS: CD25+ Treg are crucial in whey allergy prevention by n-3 LCPUFA.

Can food allergy be prevented? The current evidence.

Food allergy is a recognized public health concern, for which preventative strategies are required. Although an intervention that adequately protects against the development of food allergy has still to be identified, limited benefits have been shown for the prevention of related allergic conditions such as eczema, and to a lesser extent asthma and rhinitis; these benefits are usually limited to at-risk populations. Prevention strategies need to be tested using randomized controlled study designs that account for the numerous methodological challenges, safety concerns, and necessary ethical limitations.