PCA loading plot, visualizing all included variables on 2 axes: those with the largest variation along the horizontal (first component) axis, and those with less variation along the vertical axis (second component). Approximately 18% (9.60% + 8.15% = 17.8%) of the total variability is described by the model. Variables located close together in the same quadrant are positively correlated. Variables located in diagonally opposed quadrants are negatively correlated. One of the stronger associations is seen between dishwashing by hand (handdish) and allergic disease (asthma, eczema, or ARC, labeled as Tot_all in the figure). In the figure, handdish is located in the lower left quadrant and Tot_all in the right upper quadrant, indicating a negative correlation between these 2 variables.
Adjusted ORs and 95% CIs for eczema, asthma, ARC, and total allergy (any of the 3 diseases) when analyzed with respect to dishwashing method used by the family. The prevalences of eczema and total allergy were significantly lower in children from families who use hand dishwashing (n = 126) instead of machine dishwashing (n = 868), whereas asthma revealed a borderline significance. Confounders were adjusted for in a hierarchical multiple logistic regression model, with parental history of allergy, day care attendance, and pet keeping during infancy as independent variables.
The prevalence of total allergy (eczema, asthma, or ARC) according to the number of protective factors reported for the child’s family: that is, the number of factors included in the umbrella term traditional cooking (hand dishwashing, use of fermented food, or buying food from farm). Differences are expressed as adjusted ORs and 95% CIs, and confounders were adjusted for in a hierarchical multiple logistic regression model with parental history of allergy, day care attendance, pet keeping during infancy, and father born in Sweden, as independent variables.
↵a Question: “Does the child eat food that includes fermented vegetables (such as sauerkraut or fermented cucumber) or other fermented foodstuffs?” Responses: never/almost never; at least once a month.
↵b Question: “Do you sometimes buy hens’ eggs, meat, or unpasteurized milk directly from a farm?” Responses: yes; no.
↵c Question: “During the child’s first year of life, how often was he/she given home-cooked food?” Responses: never/almost never; approximately half the time; most of the time/always.