According to this study, higher consumption of dairy products other than milk (such as cheese or yogurt), but not just milk or total dairy consumption, was linked to a lower risk of wheezing in the previous 12 months, but no link was found between dairy consumption and asthma confirmed by a doctor or use of asthma medication. In a large sample of Middle-Eastern children and adolescents, the current study could investigate the connection between dairy consumption and asthma symptoms.
Our findings are consistent with those of a cross-sectional study of 1601 participants conducted in Melbourne, which indicated a negative relationship between dairy product consumption and asthma (21). PIAMA birth cohort research, which included 2978 children, found that frequent use of milk fat-containing items is linked to a lower risk of asthma symptoms (8). Low levels of vitamin A and milk consumption were linked to an increased risk of airway blockage among heavy smokers, according to data from the national health and examination survey I (NHANES I) in the United States (34). In contrast to the findings of the current study, Malaeb et al. found that consuming less milk on a regular basis reduced the current asthma risk (35). Another study of 1014 students (5–14 years old) discovered a link between dietary variables and allergen exposure at school, with the connections between allergen exposure and respiratory symptoms being stronger among those who consumed less fresh milk and milk fat and more margarine (20). Higher maternal intake of total dairy products, cheese, yogurt, and calcium during pregnancy may reduce the risk of infantile eczema in the previous 12 months, physician-diagnosed asthma, physician-diagnosed atopic eczema, and physician-diagnosed atopic eczema, according to Miyake et al. in a pre-birth cohort study in Japan (36). In a cross-sectional study, Hijazi et al. found that decreased milk consumption is linked to a higher prevalence of asthma symptoms and allergy symptoms (19). According to the findings of a study conducted by Hallit et al., eating dairy products (even a few times a week) had an inversely significant influence on asthma compared to never eating them (37). Tabak et al., on the other hand, found no apparent link between dairy products and asthma (25). Milk and dairy products are high in saturated fat, which has been linked to a lower incidence of allergy disorders and asthma (35). Butter and whole milk consumption may be beneficial for asthma and allergy symptoms. However, margarine consumption was found to be detrimental to asthma and allergy symptoms (38). The beneficial effect of milk and butter may be due to the fatty acid makeup of milk (38) and the fact that lactose digestion differs from that of other carbohydrates, and it may serve as a conditional prebiotic (39). Their prebiotic activity is probably related to the stimulation of the growth of beneficial bacteria in the intestines, which may modulate immune responses and thus protect humans from asthma and allergies (40). Milk proteins, including-lactalbumin,-lactoglobulin, and immunoglobulins, as well as whey proteins such as serum albumin, lactoferrin, and lactoperoxidase, as well as various enzymes and cytokines found in dairy products, are thought to have a part in this protective effect (41).
Many researchers have looked at the medicinal and preventative effects of yogurt and the lactic acid bacteria that are widely utilized in yogurt production (42). The link between cytokine imbalance and asthma symptoms is thought to be significant. A shift away from a TH1 interferon gamma (IFN-γ) pattern toward a TH2 (IL-4, IL-5, and IL-13) profile is seen in Atopic illness immunological responses. Incomplete IFN-γ production, according to these findings, predisposes to the development of allergy disorders and asthma (43). Long-term ingestion of substantial amounts of yogurt (450 g/d) has been found in human studies to boost the production of IFN-γ by lymphocytes, separated T cells. Interferon gamma is a lymphokine that activates macrophages. Oral ingestion of Lactobacillus casei and other probiotic strains (44), for example, has been shown to reduce immunoglobulin E (IgE) production. These findings suggest eating yogurt could help to reduce IgE-mediated diseases, including asthma (42). Conjugated linoleic acid is one of the other probable pathways discussed in the papers (CLA). This fatty acid, which is said to occur naturally in dairy fats, is a diverse set of positional and geometric isomers of linoleic acid with over 25 isomers. These compounds have a wide range of biological features that could help asthma sufferers, including impacts on energy management, lipid metabolism, inflammation, and immunological function. CLA's metabolic benefits, which include fat loss and adipokine regulation, may be beneficial for respiratory mechanics and systemic inflammation, which may apply to asthmatic airway inflammation (45).
The current study includes various flaws that should be taken into account when evaluating the results. The current study relied solely on self-reported data, with questions about milk and other dairy products included in the questionnaire. Furthermore, although the associations were adjusted for several possible confounding variables, we had no data on some other variables, including energy intake, physical activity, and other variables. Therefore, residual confounding might be a limitation of the current study. As each dairy product intake was not asked in the questionnaire, we were unable to check the association for each dairy product. In cross-sectional studies, the dependent and independent variables were gathered at the same time; therefore, no causal association can be inferred from their results. Therefore, future prospective studies are highly recommended.