Introduction:
Asthma is a breathing disorder characterized by spasm and swelling of the bronchial airways along with excessive excretion of a viscous mucus that can also make breathing difficult. Asthma affects approximately 7% of the population of the United States and causes 4,210 deaths per year. Although it occurs at all ages, it is most common in children younger than 10 affecting, over 7 million American kids.
The incidence of asthma is rising rapidly in the United States, especially in children. Reasons often given to explain the rise in asthma include the following:
• Increased stress on the immune system due to factors such as greater chemical pollution in the air, water, and food
• Lack of breast-feeding, earlier weaning and earlier introduction of solid foods to infants
• Insufficient intake of omega-3 fatty acids during pregnancy and infancy
• Genetic manipulation of plants, resulting in food components with greater allergenic tendencies
• Frequent antibiotic use during infancy
Background Data:
In a previous analysis of seven studies involving more than 12,000 children, researchers at the University of British Columbia found that those infants prescribed antibiotics before their first birthday, were more than twice as likely as the untreated kids to develop asthma. And, if they had multiple courses of antibiotics, it bumped up the risk even higher, a 16 percent increase for every course of the drugs taken before age one.
There are a couple of explanations for this association between antibiotic use and asthma. –One is that antibiotics contribute to a state of “excess hygiene” leading to a reduced exposure to microbes which, in turn, creates an over-sensitive immune system, mounting an over-the-top allergic reaction to pollen and dust mites, ultimately leading to asthma. Research has also shown that children who grow up on farms have lower allergy and asthma rates, a phenomenon attributed to their regular exposure to microorganisms present in their environment.
The second explanation is that antibiotics have a negative effect on the normal flora of the gastrointestinal and respiratory passages. Some studies have shown that giving probiotics (active cultures of Lactobacillus and Bifidobacteria species) lowers the risk of atopic allergic disease like asthma and eczema (discussed below in Commentary section).
New Data:
Two new studies have come out recently to support the excess hygiene theory of asthma. In the first study, researchers from Johns Hopkins found that infants who grew up in homes with a greater variety of bacteria, as well as mouse and cat dander, and cockroach droppings, had lower rates of wheezing at age 3, compared with children not exposed to these allergens soon after birth.1
The second study, conducted at Harvard Medical School, found a significant dose-response for asthma with antibiotic exposure during the first year of life.2 The more antibiotics an infant was exposed to the more likely they were to develop asthma. For instance, antibiotic use during the first year of life doubled the risk for asthma and when children got five or more antibiotic courses, the odds ratio for persistent asthma was nearly doubled again.
Commentary:
These studies highlight the symbiotic natural relationship between microbes and humans. This delicate balance is being disrupted leading to a faulty immune response, allergies, and asthma. Beyond exposing kids to a “less hygienic” infancy, there are a couple of other measures that deserve mention.
First, there are some really interesting studies that have been done with fish oil supplementation during pregnancy that show that this practice may reduce sensitization to common food allergens and reduce prevalence and severity of both eczema and asthma. In 1990, 533 women with normal pregnancies were randomly assigned at 30 weeks of pregnancy to receive four fish oil capsules providing 2.7 g EPA+DHA per day; four similar-looking capsules with olive oil; or no oil capsules. The rate of developing asthma due to allergies was reduced by 87% in the fish oil compared with the olive oil group.
Think about the public health impact of giving mothers fish oil supplements on asthma alone. But, that is not all these oils do, they are also linked with reducing the risk of post-partum depression, as well as boost baby brain development and IQ.
In regards to probiotics preventing asthma, the data is mixed and a recent analysis published in the New England Journal of Medicine concluded that probiotic supplementation did not seem to prevent asthma. However, a closer look is necessary. If probiotics are to be helpful, a key reason may be the influence on mucosal IgA, an antibody that participates in allergy elimination. In a study of 237 allergy-prone infants given a combination of four probiotic strains or placebo, researchers found that the probiotic supplementation increased fecal IgA, while reducing inflammatory markers. In infants with high fecal IgA concentration at the age of 6 months, the risk of having any allergic disease or any IgE-associated (atopic) disease before the age of 2 years was cut by nearly 50%.4 High intestinal IgA in early life is associated with reduced intestinal inflammation, as well as a reduced risk for asthma and allergic diseases.
The reason why some of the studies with probiotics failed may have been due to a few factors: (1) perhaps the strain(s) used was not effective in raising mucosal IgA levels; (2) perhaps a combination of strains are required versus a single strain in order to raise mucosal IgA; and (3) perhaps the dosage given was not sufficient.
The bottom line is that there is enough experimental and clinical evidence to support fish oil and probiotic supplementation throughout a person’s life, but especially during infancy and childhood. It just makes good sense.
References:
1. Lynch SV, Wood RA, Boushey H, et al. Effects of early-life exposure to allergens and bacteria on recurrent wheeze and atopy in urban children. J Allergy Clin Immunol. 2014 May 28. doi: 10.1016/j.jaci.2014.04.018.
2. Ong MS, Umetsu DT, Mandl KD. Consequences of antibiotics and infections in infancy: bugs, drugs, and wheezing. Ann Allergy Asthma Immunol. 2014 May;112(5):441-445.
3. Olsen SF, Østerdal ML, Salvig JD, et al. Fish oil intake compared with olive oil intake in late pregnancy and asthma in the offspring: 16 y of registry-based follow-up from a randomized controlled trial. Am J Clin Nutr. 2008 Jul;88(1):167-75.
4. Kukkonen K, Kuitunen M, Haahtela T, et al. High intestinal IgA associates with reduced risk of IgE-associated allergic diseases. Pediatr Allergy Immunol. 2010 Feb;21(1 Pt 1):67-73.
