Cow's milk consumption and processing and the development of type 1 diabetes and asthma in children

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http://urn.fi/URN:ISBN:978-951-51-7590-8
Title: Cow's milk consumption and processing and the development of type 1 diabetes and asthma in children
Author: Koivusaari, Katariina
Contributor: University of Helsinki, Faculty of Agriculture and Forestry, Department of Food and Nutrition
Doctoral Program in Population Health
Finnish Institute for Health and Welfare (THL), Department of Public Health and Welfare
Publisher: Helsingin yliopisto
Date: 2021-11-19
Language: en
Belongs to series: URN:ISSN:2342-317X
URI: http://urn.fi/URN:ISBN:978-951-51-7590-8
http://hdl.handle.net/10138/335447
Thesis level: Doctoral dissertation (article-based)
Abstract: Cow’s milk has been associated with the development of both type 1 diabetes and asthma in children, although in different ways. Consumption of cow’s milk has been associated with an increased risk of the development of type 1 diabetes. On the other hand, several cross-sectional studies show that consumption of raw, unprocessed milk is associated with a decreased risk of asthma or atopy when compared to no consumption of raw milk or to consumption of sterilized milk. Little is known about differently processed milk products. The aim of this thesis was to study, in a birth cohort setting, whether the consumption of differently processed milk products is associated with the risk of islet autoimmunity or asthma in children. To study that, a novel processing-based classification of milk products was created in the national food composition database as part of this thesis. This classification was also used to evaluate children’s consumption of differently processed milk products, as such information was lacking. This thesis is based on the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Nutrition Study, comprising children genetically predisposed to type 1 diabetes born in Tampere or Oulu University hospitals from 1996 to 2004 (N=6081). The nutritional information of the participants was collected by food records at the age of 3 and 6 months, and 1, 2, 3, 4, 5, and 6 years. The consumption of milk products was calculated from the food records using the national food composition database. Each milk product item in the national food composition database was classified according to the adopted heat-treatment (low-pasteurized or less heated/high-pasteurized at <100°C/high-pasteurized at 100°C or sterilized) and homogenization (yes/no/fat-free). The classification was done principally based on literature. The study participants were followed for type 1 diabetes-related autoantibodies regularly until the age of 15 years. The primary outcome in the diabetes-related study was islet autoimmunity by the age of 6 years, defined as repeated positivity for islet cell autoantibodies and at least one biochemical antibody tested: insulin autoantibodies, antibodies to the 65 kD isoform of glutamic acid decarboxylase, and the tyrosine phosphatase-related islet antigen-2 molecule. The secondary outcome was islet autoimmunity by the age of 15 years. Of the 6081 children within the DIPP Nutrition Study, 4075 children were still in the DIPP follow-up at the age of 5 years, and of them 3781 participated in the DIPP Allergy and Asthma Study. The information on asthma was collected at the age of 5 years by using an ISAAC-based questionnaire. Outcomes in the asthma study were asthma, atopic asthma, and nonatopic asthma by the age of 5 years. Asthma was defined as doctor-diagnosed asthma plus wheeze or use of asthma medication during the preceding 12 months. Atopic asthma was defined as IgE-positive asthma, and nonatopic asthma as IgE-negative asthma. Joint models for longitudinal and time-to-event data were used as the statistical approach to study the association between consumption of differently processed milk products and islet autoimmunity and asthma. Almost all study participants [e.g., at the age of 3 years, 3401 of 3460 (98.3%)] consumed cow’s milk. During the first year of life, high-pasteurized at 100°C or sterilized milk products were consumed in higher amounts, while at ages 1–6 years low-pasteurized milk products were predominant. Homogenized milk products were consumed in higher amounts than nonhomogenized ones. Consumption of fat-free milk products increased by age. By the age of 6 years, islet autoimmunity developed in 246 (4.4%) of the 5545 children included in the analyses. High consumption of cow’s milk products was associated with an increased risk of islet autoimmunity [energy-adjusted hazard ratio (95% confidence intervals) 1.06 (1.02, 1.11)]. In addition, consumption of nonfermented [1.06 (1.01, 1.10)], fermented [1.35 (1.10, 1.67)], and homogenized [1.07 (1.02, 1.12)] milk products were associated with an increased risk. No processing type stood out as a particular risk factor. Asthma developed in 184 (6.0%) of the 3053 children included in the analyses, by the age of 5 years. Asthma in 101 (54.9%) children was atopic, and in 75 (40.8%) children nonatopic. The asthma type of 8 (4.3%) children could not be categorized. Consumption of high-pasteurized at 100°C or sterilized milk products [adjusted hazard ratio (95% confidence intervals) 1.06 (1.01, 1.10)] including milk-based infant formulas [1.15 (1.07, 1.23)] was associated with an increased risk of asthma. Consumption of cow’s milk products [1.09 (1.03, 1.15)], nonfermented milk products [1.08 (1.02, 1.14)], infant formulas [1.23 (1.13, 1,34)], and high-pasteurized at 100°C or sterilized milk products [1.08 (1.02, 1.15)] were associated with an increased risk of nonatopic asthma. In parallel to several previous studies, the results of this thesis suggest that high consumption of cow’s milk and cow’s milk products is associated with the development of the two immunological diseases in children. Processing of milk did not play a significant role in the association to islet autoimmunity. The consumption of high-pasteurized at 100°C or sterilized milk products was associated with an increased risk of asthma. No such association was seen for low-pasteurized milk products. This implies that processing may change the immunological properties of milk and thus play a role in the development of immunological diseases. As milk and milk products are commonly used in substantial amounts by Finnish children, future studies are needed to confirm the results and to enlighten the mechanisms behind the associations.Lehmänmaidon kulutus on yhdistetty kohonneeseen tyypin 1 diabeteksen riskiin. Toisaalta prosessoimattoman raakamaidon kulutuksella on havaittu yhteys pienempään astman ja atopian riskiin. Väitöskirjan tarkoituksena oli tutkia, onko eri tavoin prosessoitujen maitovalmisteiden kulutus yhteydessä tyypin 1 diabeteksen tai astman kehittymiseen lapsilla. Väitöskirja pohjautuu suomalaiseen Tyypin 1 diabeteksen ennustaminen ja ehkäisy (DIPP) -ravitsemustutkimukseen, jossa on seurattu Tampereen ja Oulun yliopistollisissa sairaaloissa vuosina 1996–2004 syntyneitä lapsia. Lapsilta seurattiin diabeteksen esiastetta kuvaavien autovasta-aineiden ilmaantumista seeruminäytteisiin 3–12 kuukauden välein. Tieto astmasta kerättiin lomakkeella lapsen ollessa viisivuotias. Ravintotiedot kerättiin toistuvien ruokapäiväkirjojen avulla. Maitovalmisteiden kulutus laskettiin käyttäen kansallista elintarvikkeiden koostumustietokantaa, jonka maitovalmisteet luokiteltiin kuumennuskäsittelyn ja homogenoinnin perusteella. Lähes kaikki lapset käyttivät maitovalmisteita. Ensimmäisen ikävuoden aikana käytettiin eniten voimakkaasti lämpökäsiteltyjä (korkeapastöroituja ≥100°C:ssa tai steriloituja maitovalmisteita), kun taas 1–6 vuoden iässä pastöroituja maitovalmisteita käytettiin enemmän. Homogenoituja maitovalmisteita käytettiin suurempia määriä kuin homogenoimattomia. Rasvattomien maitovalmisteiden käyttö lisääntyi iän myötä. Runsas maitovalmisteiden kulutus oli yhteydessä kohonneeseen tyypin 1 esiasteen riskiin. Mikään prosessointityyppi ei erottunut erityisenä riskitekijänä suhteessa tyypin 1 diabeteksen esiasteeseen. Voimakkaasti lämpökäsiteltyjen maitovalmisteiden, joihin myös äidinmaidonkorvikkeet luokiteltiin, kulutus oli yhteydessä kohonneeseen astman riskiin. Atopian suhteen jaoteltuna äidinmaidonkorvikkeiden ja muiden voimakkaasti lämpökäsiteltyjen maitovalmisteiden kulutus oli yhteydessä korkeampaan ei-atooppisen astman riskiin, mutta ei atooppisen astman riskiin. Vastaavaa riskiyhteyttä ei nähty pastöroiduilla maitovalmisteilla. Tämä viittaa siihen, että prosessointi saattaa vaikuttaa maidon immunologisiin ominaisuuksiin. Koska suomalaiset lapset käyttävät maitoa ja maitovalmisteita runsaita määriä, tutkimusten on jatkossa tärkeää selventää yhteyksiä ja valottaa mekanismeja niiden takana.
Subject: elintarviketieteet
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