Studies Showing Raw (Farm) Milk Protective Against Asthma and Allergies

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Riedler J and others. Exposure to farming in early life and development of asthma and allergy: a cross-sectional survey. Lancet 2001 Oct 6;358(9288):1129-33.

Abstract

BACKGROUND:
A farming environment protects against development of asthma, hay fever, and atopic sensitisation in children. We aimed to establish whether increased exposure to microbial compounds has to occur early in life to affect maturation of the immune system and thereby reduces risk for development of allergic diseases.

METHODS:
We did a cross-sectional survey in rural areas of Austria, Germany, and Switzerland. 2618 (75%) of 3504 parents of 6-13-year-old children completed a standardised questionnaire on asthma, hay fever, and atopic eczema. Children from farming families, and a random sample of non-farmers’ children, who gave consent for blood samples to be obtained for measurements of specific serum IgE antibodies to common allergens were invited to participate (n=901).

FINDINGS:
Exposure of children younger than 1 year, compared with those aged 1-5 years, to stables and consumption of farm milk was associated with lower frequencies of asthma (1% [3/218] vs 11% [15/138]), hay fever (3% [7] vs 13% [18]), and atopic sensitisation (12% [27] vs 29% [40]). Protection against development of asthma was independent from effect on atopic sensitisation. Continual long-term exposure to stables until age 5 years was associated with the lowest frequencies of asthma (0.8% [1/122]), hay fever (0.8% [1]), and atopic sensitisation (8.2% [10]).

INTERPRETATION:
Long-term and early-life exposure to stables and farm milk induces a strong protective effect against development of asthma, hay fever, and atopic sensitisation.

Perkin MR and DP Strachan DP. Which aspects of the farming lifestyle explain the inverse association with childhood allergy? J Allergy Clin Immunol 2006 Jun;117(6):1374-81.

BACKGROUND:
Farmers’ children have a reduced prevalence of allergic disorders. The specific protective environmental factors responsible are not yet identified.

OBJECTIVE:
We sought to determine whether farmers’ children in the rural county of Shropshire, England, have a reduced risk of atopy and, if so, to identify the factors responsible.

METHODS:
The Study of Asthma and Allergy in Shropshire was a 2-stage cross-sectional study. In stage 1 a questionnaire to elicit allergic status, diet, and farming exposure was completed by the parents of 4767 children. In stage 2 a stratified subsample of 879 children underwent skin prick testing and measurement of domestic endotoxin.

RESULTS:
Compared with rural nonfarming children, farmers’ children had significantly less current asthma symptoms (adjusted odds ratio (OR), 0.67; 95% CI, 0.49-0.91; P = .01) and current seasonal allergic rhinitis (adjusted OR, 0.50; 95% CI, 0.33-0.77; P = .002) but not current eczema symptoms (adjusted OR, 0.91; 95% CI, 0.68-1.21; P = .53) or atopy (adjusted OR, 0.68; 95% CI, 0.40-1.16; P = .15). In contrast, current unpasteurized milk consumption was associated with significantly less current eczema symptoms (adjusted OR, 0.59; 95% CI, 0.40-0.87; P = .008) and a greater reduction in atopy (adjusted OR, 0.24; 95% CI, 0.10-0.53; P = .001). The effect was seen in all children, independent of farming status. Unpasteurized milk consumption was associated with a 59% reduction in total IgE levels (P < .001) and higher production of whole blood stimulated IFN-gamma (P = .02).

CONCLUSION:
Unpasteurized milk consumption was the exposure mediating the protective effect on skin prick test positivity. The effect was independent of farming status and present with consumption of infrequent amounts of unpasteurized milk.

CLINICAL IMPLICATIONS:
Unpasteurized milk might be a modifiable influence on allergic sensitization in children.

Waser M, Michels KB, Bieli C et al. Inverse association of farm milk consumption with asthma and allergy in rural and suburban populations across Europe. Clinical Exp Allergy 2007; 37:661–70.

Abstract

BACKGROUND:
Dietary interventions as a means for atopy prevention attract great interest. Some studies in rural environments claimed an inverse association between consumption of farm-produced dairy products and the prevalence of allergic diseases, but current evidence is controversial.

OBJECTIVE:
To investigate whether consumption of farm-produced products is associated with a lower prevalence of asthma and allergy when compared with shop-purchased products.

METHODS:
Cross sectional multi-centre study (PARSIFAL) including 14,893 children aged 5-13 years from five European countries (2823 from farm families and 4606 attending Steiner Schools as well as 5440 farm reference and 2024 Steiner reference children). A detailed questionnaire including a dietary component was completed and allergen-specific IgE was measured in serum.

RESULTS:
Farm milk consumption ever in life showed a statistically significant inverse association with asthma: covariate adjusted odds ratio (aOR) 0.74 [95% confidence interval (CI) 0.61-0.88], rhinoconjunctivitis: aOR 0.56 (0.43-0.73) and sensitization to pollen and the food mix fx5 (cut-off level of >or=3.5 kU/L): aOR 0.67 (0.47-0.96) and aOR 0.42 (0.19-0.92), respectively, and sensitization to horse dander: aOR 0.50 (95% CI 0.28-0.87). The associations were observed in all four subpopulations and independent of farm-related co-exposures. Other farm-produced products were not independently related to any allergy-related health outcome.

CONCLUSION:
Our results indicate that consumption of farm milk may offer protection against asthma and allergy. A deepened understanding of the relevant protective components of farm milk and a better insight into the biological mechanisms underlying this association are warranted as a basis for the development of a safe product for prevention.

Comment: Perkin MR. Unpasteurized milk: health or hazard? Clinical and Experimental Allergy 2007 May; 35(5) 627-630

The literature identifying that farming children have a reduced prevalence of allergic disorders compared with other rural children is now substantial. It is clear that a diversity of putative protective factors are involved: exposure to barns and stables, early contact with farm animals and working on a farm during pregnancy. The paper by Waser et al. [2] adds to the small but growing body of evidence that consumption of unpasteurized milk is another factor mediating a protective effect on allergic disorders.

Loss G and others. The protective effect of farm milk consumption on childhood asthma and atopy: the GABRIELA study. Journal of Allergy Clin Immunol 2011 October 128(4):766-773.e4

Source
Swiss Tropical and Public Health Institute, Basel, Switzerland. georg.loss@unibas.ch

Abstract

BACKGROUND:
Farm milk consumption has been identified as an exposure that might contribute to the protective effect of farm life on childhood asthma and allergies. The mechanism of action and the role of particular constituents of farm milk, however, are not yet clear.

OBJECTIVE:
We sought to investigate the farm milk effect and determine responsible milk constituents.

METHODS:
In rural regions of Germany, Austria, and Switzerland, a comprehensive questionnaire about farm milk consumption and other farm-related exposures was completed by parents of 8334 school-aged children, and 7606 of them provided serum samples to assess specific IgE levels. In 800 cow’s milk samples collected at the participants’ homes, viable bacterial counts, whey protein levels, and total fat content were analyzed. Asthma, atopy, and hay fever were associated to reported milk consumption and for the first time to objectively measured milk constituents by using multiple regression analyses.

RESULTS:
Reported raw milk consumption was inversely associated to asthma (adjusted odds ratio [aOR], 0.59; 95% CI, 0.46-0.74), atopy (aOR, 0.74; 95% CI, 0.61-0.90), and hay fever (aOR, 0.51; 95% CI, 0.37-0.69) independent of other farm exposures. Boiled farm milk did not show a protective effect. Total viable bacterial counts and total fat content of milk were not significantly related to asthma or atopy. Increased levels of the whey proteins BSA (aOR for highest vs lowest levels and asthma, 0.53; 95% CI, 0.30-0.97), α-lactalbumin (aOR for interquartile range and asthma, 0.71; 95% CI, 0.52-0.97), and β-lactoglobulin (aOR for interquartile range and asthma, 0.62; 95% CI, 0.39-0.97), however, were inversely associated with asthma but not with atopy.

CONCLUSIONS:
The findings suggest that the protective effect of raw milk consumption on asthma might be associated with the whey protein fraction of milk.

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