Dietary approaches to the prevention of food allergy

Preparation, properties, and uses of enzymatic milk protein hydrolysates

Enzymatic hydrolysis of milk proteins has been a subject of numerous research studies and patents. The driving force for these studies has been the increased utilization of milk proteins. The industrial uses of milk proteins are based on their unique composition, functionality, and nutritive values. The diversity of milk protein fraction, the large number of proteinases, and controlled hydrolysis conditions used resulted in the preparation of hydrolysates suitable for several purposes. Enzymatic hydrolysis of milk proteins modifies the techno-functional and biofunctional properties of hydrolysates depending on the enzyme(s) and hydrolysis conditions used. Milk protein hydrolysates (MPH) are used commonly in normal and clinical nutrition and as a functional food ingredient. In the present review, emphasis has been made to highlight methods applied for the preparation of MPH, and the functional properties and utilization of the obtained hydrolysates.

Clinical safety evaluation of marine oil derived from Calanus finmarchicus

Marine oils are rich in polyunsaturated fatty acids (PUFAs), including docosahexaenoic and eicosapentaenoic acid. These PUFAs are associated with health benefits and additional sustainable sources of marine oils are desirable. One of the source organisms is Calanus finmarchicus, a copepod endemic to the North Atlantic. PUFAs in the lipid fraction of this organism are largely in the form of wax esters. To assess the safety of these wax esters as a source of PUFAs, a randomized, double-blinded, placebo-controlled clinical trial was conducted whereby 64 subjects consumed 2 g Calanus oil in capsule form daily for a period of one year. A group of 53 subjects consumed placebo capsules. At baseline, 6-, and 12-months, series of evaluations were conducted, including: vital signs, clinical chemistry and hematological evaluations, and adverse event reporting. Food intake and physical exercise were controlled by means of a questionnaire. There were no effects on Calanus oil treatment on any of the safety parameters measured. A slight increase in the incidence of eczema was reported in the Calanus oil group, but the response was minor in nature, not statistically significant after controlling for multiple comparisons, and could not be attributed to treatment.

Acute allergic reactions in Vietnamese children after drinking a new milk product

In early October 2009, pediatricians in hospitals in Ho Chi Minh City (HCMC) reported an unusual increase in the number of children presenting with an acute onset of itchy rash and some with breathing difficulties shortly after drinking milk products. The pediatricians considered the illness to be an allergic reaction to milk. The objective of our investigation was to identify the cause of this acute illness. Following early case reports, all hospitals in HCMC were requested to report cases of this illness. Parents were advised to take children with symptoms to a hospital immediately. A case-series was conducted to generate hypotheses on the possible causes of the illness and was followed by a case-control study to test the hypothesis. Parents of all cases and controls were interviewed face-to-face. The association between food items and the allergy was tested using conditional logistics regression. From 9 to 28 October 2009, 19 cases fulfilled the case definition, and 16 of the 17 cases included in the study had consumed milk supplemented with galacto-oligosaccharides (GOS) shortly before the onset of illness. Fifty age-matched, neighborhood controls were enrolled into the case control study. Of the 30 food items consumed by study participants in the preceding 24 h, only the odds ratio (OR) of milk supplemented with GOS was statistically significant: OR=34.0 (95% CI=3.9, 294.8). Laboratory tests of this milk product did not reveal any unusual properties, chemicals, or other toxic substances. This is the first report of an acute allergic reaction to fresh milk supplemented with GOS. However, the specific allergen in this product was not identified. Further cases were not reported once this product was withdrawn from sale. Vietnam's food safety authorities should expand laboratory capacity to detect allergens in food products.

Knowledge and practice of physicians and nutritionists regarding the prevention of food allergy

BACKGROUND & AIMS

To evaluate the knowledge and practice of pediatricians, pediatric gastroenterologists, allergists and nutritionists regarding the primary prevention of food allergy.

METHODS

A descriptive, cross-sectional study that enrolled pediatricians (n = 80), pediatric gastroenterologists (n = 120), allergists (n = 100) and nutritionists (n = 220). A self-administered questionnaire concerning the current recommendations was used.

RESULTS

Despite the lack of current recommendations, 17.1% (n = 89) of all professionals, mainly nutritionists, recommended a maternal exclusion diet during pregnancy. More professionals in the sample group, 40.8% (n = 212), recommended a maternal exclusion diet during breastfeeding, and the rates of recommendation were higher in nutritionists and pediatricians compared to allergists and pediatric gastroenterologists (p < 0.001). Regarding the recommended timing of the introduction of complementary feeding, 41.9% (n = 218) of the professionals recommended modifying the age of introduction to prevent the development of food allergy. The majority of the professionals believed that prebiotics (61.2%; n = 318) and probiotics (44.4%; 231) prevent the development of food allergy. The recommended age of introduction for the main allergenic foods was 12 months.

CONCLUSIONS

This study revealed that there are gaps in the knowledge of professionals about the primary prevention of food allergy.

Food allergy and atopic dermatitis: how are they connected?

Food allergy predominantly affects children rather than adults with atopic dermatitis (AD). Early food sensitization has been found to be significantly associated with AD. Three different patterns of clinical reactions to food allergens in AD patients have been identified: 1) immediate-type symptoms, 2) isolated eczematous late-type reactions, and 3) combined reactions. Whereas in children, allergens from cow's milk, hen's egg, soy, wheat, fish, peanut, or tree nuts are primarily responsible for allergic reactions, birch pollen-related food allergens seem to play a major role in adolescent and adults with AD in Central and Northern Europe. Defects in the epidermal barrier function seem to facilitate the development of sensitization to allergens following epicutaneous exposure. The relevance of defects in the gut barrier as well as genetic characteristics associated with an increased risk of food allergy remain to be further investigated. Many studies focus on sufficient strategies of prevention, which actually include breastfeeding or feeding with hydrolyzed formula during the first 4 months of life.

Aberrant interaction of the gut immune system with environmental factors in the development of food allergies

The gastrointestinal immune system is a major component of the mucosal barrier, which maintains an immunologic homeostasis between the host and the harsh environment of the gut. This homeostasis is achieved by immunologic quiescence, and its dysregulation is thought to result from the development of immune diseases such as food allergies. Recent findings have revealed versatile pathways in the development of intestinal allergies to certain food antigens. In this review, we summarize the regulatory and quiescence mechanisms in the gut immune system and describe aberrant interactions between the host immune system and the gut environment in the development of food allergies.

Clinical practice: Breastfeeding and the prevention of allergy

The increase in allergic disease prevalence has led to heightened interest in the factors determining allergy risk, fueled by the hope that by influencing these factors one could reduce the prevalence of allergic conditions. The most important modifiable risk factors for allergy are maternal smoking behaviour and the type of feeding. A smoke-free environment for the child (to be), exclusive breastfeeding for 4-6 months and the postponement of supplementary feeding (solids) until 4 months of age are the main measures considered effective. There is no place for restricted diets during pregnancy or lactation. Although meta-analyses suggest that hypoallergenic formula after weaning from breastfeeding grants protection against the development of allergic disease, the evidence is limited and weak. Moreover, all current feeding measures aiming at allergy prevention fail to show effects on allergic manifestations later in life, such as asthma. In conclusion, the allergy preventive effect of dietary interventions in infancy is limited. Counselling of future parents on allergy prevention should pay attention to these limitations.