Talking Allergies, Asthma, Eczema, & The Hygiene Hypothesis
Hygiene Hypothesis | Allergy | T Helper Cell
Asthma and the Hygiene Hypothesis — NEJM
The Inner-City Asthma Study (and countless others) showed that improved hygiene can alleviate asthma and allergies once they have developed. These results may contradict some popular misconceptions regarding the hygiene hypothesis: namely, that hygiene causes allergies. The truth seems to be that depletion of the human microbiome, coupled with increased exposure to the indoor antigens described above, has resulted in increased prevalence of allergic diseases (and autoimmune diseases), and that these effects may occur during a critical period during the first year of life. Luckily, research in this field is also starting to suggest solutions, namely biome restitution. One proposal has been to purposefully dose humans with bovine or rat tapeworms, as these helminthic guests cause few side effects and have been shown to reduce rates of allergy and asthma.22 It remains to be seen whether this will catch on, but other biome restitution treatments, such as probiotics for ulcerative colitis, have shown great experimental promise and are much more palatable for patients. Mouse studies published by Fujimora and colleagues have shown that supplementation with Lactobacillus johnsonii alters the microbiome in ways that may be protective from asthma.23
Children can develop asthma and allergies from being sensitized to many indoor antigens including pets, mice, dust mites, mold, tobacco smoke, nitrogen dioxide, endotoxin, and cockroaches. Most of these are more common in the inner city than in suburbs.15 Among children admitted for asthma at Cincinnati Children’s Hospital, black children were more likely to be sensitized to Alternaria .16 While it is logical that children disproportionately exposed to a given pathogen will have the highest rates of sensitization to it, evidence differs as to whether exposure to these allergens at a young age is protective or a risk factor for the development of asthma. The longitudinal Urban Environment and Childhood Asthma (URECA) cohort study found that while cumulative exposure to allergens predicted atopy, home exposure to cockroach, mouse, and cat allergens during the first year of life was associated with .17 This suggests there may be a critical period in which exposure to allergens is protective. In addition, they found the presence of cockroaches and mice to be associated with certain bacterial populations which may have had a protective effect, suggesting an influence by these household pests on the microbiota of inner city children. Simons and colleagues, who did not focus on the first year of life, found that exposure to cockroaches at home is associated with a risk ratio of 1.96 for the development of asthma.18 In another study, pregnant Dominican and African-American women in New York City wore air samplers that measured a variety of allergens. It turned out that the presence of cockroach antigen, measured prenatally, predicted allergic sensitization of the child at ages 5-7.19 So, while the URECA study suggests that the hygiene hypothesis may hold true in the inner city, other research suggests that inner city residents are suffering from allergic diseases not because the hygiene of their environment has improved, but possibly because the opposite is true.
Natural Allergy Medication | Hygiene Hypothesis | …
Over the past few decades, doctors have arrived at a counterintuitive hypothesis about our modern, ultra-sanitized world. Too much cleanliness may be causing us to develop allergies, asthma, inflammatory bowel diseases, and other autoimmune disorders.
Even regarding allergies, there are that can't be answered by the hygiene hypothesis — such as why, in some European cities, the children of migrants from other countries than other children, even though they basically live in the same conditions. Clearly, we're
Strachan Hygiene Hypothese | Allergy | Asthma
Asthma prevalence in the United States increased from 3.5% to 8.2% between 1982 and 2009.3 Many hypotheses have been advanced in attempts to explain this. Some, such as increased awareness of the disease and increased rates and survival of premature birth, explain small parts of the increase.4,5 Others, such as changing rates of breastfeeding and increased .5 Perhaps the most important and poorly understood, at least from the public viewpoint, is the “hygiene hypothesis.”
The hygiene hypothesis was first advanced in 1989 by David Strachan in the British Medical Journal. It posits that allergic disease has increased in prevalence as the diversity of the human microbiome has been depleted due to antibiotic use, improved sanitation, and other advances in public health.6 Activation of Th1-mediated cellular immunity by certain infections at a young age is thought to suppress the proliferation of allergen-specific Th2 lymphocytes, overactivity of which is the basis of atopic diseases such as asthma.7 Now that many infectious diseases have been eradicated from the human experience, we are more disposed to develop atopic disease, or so the theory goes.
hygiene can alleviate asthma and allergies ..
Asthma and the hygiene hypothesis.
11/08/2008 · Question:What is the 'hygiene hypothesis' as it relates to asthma and allergies
Asthma and the hygiene hypothesis. Does cleanliness …
Eat Dirt Hygiene Hypothesis | Lipopolysaccharide | Allergy
THE TRUTH ABOUT ASTHMA - Health - Science
Portsmouth, Ohio Allergist | Midwest Allergy
Can Eating Local Honey Cure Allergies
There is a good deal of evidence supporting the hypothesis that modern lifestyles have contributed to the exploding prevalence of atopic diseases. For example, Amish children were shown to have lower rates of asthma, eczema, and sensitization to aeroallergens compared to farm children from the region of Switzerland from which the Amish emigrated, who in turn had significantly lower rates than Swiss non-farm children.8 Matricardi and colleagues found seropositivity for hepatitis A antibodies to be associated with significantly lower rates of allergic disease (it’s unknown whether the ).7,9 Having older siblings is also a protective factor, presumably because they expose younger sibling to various illnesses.7 Infants with older siblings were also shown to have significant differences in their gut microbiota as compared to those without, which may contribute to the development of atopic disease.10 Helminth eradication efforts have shown strong associations with increased allergic reactivity. However, studies looking at other microbial exposures have produced contradictory evidence, and it is difficult to establish clear-cut inverse associations between most disease exposures and atopy. Some Latin American countries with a high rate of exposure to various infectious diseases also have high rates of asthma.11 A German longitudinal birth cohort study showed that increased exposure to endotoxin in infancy and increased exposure to muramic acid (a fungal marker) at school age both reduced rates of asthma and other atopic conditions when patients reached school age. However, while personal and household hygiene habits, such as high rates of handwashing and dusting, were associated with lower levels of exposure to these substances, neither personal nor household hygiene practices showed an independent association with asthma rates.12 So, while the hygiene hypothesis has a strong basis in evidence, it is not as simple as its name suggests. Indeed, it has been argued that the term “hygiene hypothesis” has been counterproductive from a public health standpoint.6
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