Diet and childhood asthma in a society in transition: a study in urban and rural Saudi Arabia

Abstract

Background-The causes of the worldwide increases in asthma and allergic diseases in childhood, which seem to relate to increasing prosperity, are unknown. We have previously hypothesised that a reduction in the antioxidant component of the diet is an important factor. An investigation was undertaken of dietary and other risk factors for asthma in Saudi Arabia where major lifestyle diVerences and prevalences of allergic disease are found in diVerent communities. Methods-From a cross sectional study of 1444 children with a mean age of 12 (SD 1) years in Jeddah and a group of rural Saudi villages, we selected 114 cases with a history of asthma and wheeze in the last 12 months and 202 controls who had never complained of wheeze or asthma, as recorded on the ISAAC questionnaire. Risk factors for asthma and allergies (family history, social class, infections, immunisations, family size, and diet) were ascertained by questionnaire. Atopy was assessed by skin prick testing. Results-In univariate analyses, family history, atopy, and eating at fast food outlets were significant risk factors for wheezy illness, as were the lowest intakes of milk and vegetables and of fibre, vitamin E, calcium, magnesium, sodium, and potassium. These diVerences were present also in the urban children considered separately. Sex, family size, social class, infections, and parental smoking showed no relationship to risk. In multiple logistic regression analysis, urban residence, positive skin tests, family history of allergic disease, and the lowest intakes of vitamin E, magnesium and sodium related significantly and independently to risk. The lowest tertile of intake of vitamin E was associated with a threefold (95% CI 1.38 to 6.50) increase in risk when adjusted for the other factors. Intake of milk and vegetables both showed inverse linear relationships to being a case. Conclusions-This study suggests that dietary factors during childhood are an important influence in determining the expression of wheezy illness, after allowing for urban/rural residence, sex, family history, and atopy. The findings are consistent with previous studies in adults and with the hypothesis that change in diet has been a determinant of the worldwide increases in asthma and allergies. (Thorax 2000;55:775-779)

Vitamin C in breast milk may reduce the risk of atopy in the infant

“…Although a low dietary vitamin E intake has also been associated with current symptoms of atopic disease (Bodner et al, 1999;Hijazi et al, 2000), we found no consistent relationship between vitamin E (a-tocopherol and its ratio to fat) in breast milk and the development of atopic disease in the infant. The most plausible explanation for the discrepancy could be methodological differences.…”

Efficacy of magnesium in children with bronchial asthma

“…A suboptimal intake of dietary nutrients such as Mg was recently recognized to be a potential risk factor for asthma, especially in childhood (Baker and Ayres, 2000;Hijazi et al, 2000). Our study demonstrated that a large oral dose of Mg (with an atoxic nature) did not cause any disturbances.…”

Associations of intake of antioxidant vitamins and fatty acids with asthma in pre-school children

“…Given that the size of our study population was 452, we had power of 23 % to detect an OR of 0?61, which was observed for the association between asthma and fruit intake at the two-sided 5 % significance level. Among five previously cited articles regarding childhood asthma and antioxidant nutrients, the case-control studies were composed of a small number of children, the smallest including twentythree cases and twenty-three controls (10,11) . The remaining three cross-sectional studies were conducted based on the data from over 1000 participants (12)(13)(14) .…”

“…In addition to the food records, we obtained an estimate of school lunch intake by measuring the leftovers with the help of dietitians. All of the abovecited studies used an FFQ (10)(11)(12)18,19,21,23,24) or dietary recall instrument administered to mothers (13,14,22) . In addition, some studies included a limited number of food items in the FFQ.…”

“…Therefore, it is postulated that a lower dietary intake of antioxidants induced by dietary change leads to the attenuation of antioxidant defence in the lung and enhances susceptibility to airway inflammation and asthma (3,9) . Epidemiological studies have investigated the relationship of dietary antioxidants and fat intake to asthma; however, indisputable results have not been obtained (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26) . So far, only one systematic review on diet and childhood asthma has been done, which also concluded that the evidence for the link between vitamins and fat and asthma was insufficient (27) .…”