Tag Archives: hygiene

Cure asthma: Pseudoscience?

I just came around of an EU funded research program “Cure, Eubiosus Reinstatement Therapy” that has many characteristics of quack science.

For a definition of quackery I suggest to look for Continue reading Cure asthma: Pseudoscience?

Window of Opportunity

I very much liked the “Window of Opportunity” in the Nestle Nutrition Workshop Series 61, published by Karger in 2008. Page 180 has an interesting account of the hygiene hypothesis:

Dr. Bier: … The other is the issue of the hygiene hypothesis, the cleaner environment. We are just in a somewhat less dirty environment, we are not in a clean environment, and that is the problem I have with that particular approach.

So, I am not alone

Dr. Barker:… I am guilty of inventing the term “hygiene hypothesis” as an explanation of the epidemic of appendicitis that followed the introduction of running hot water into housing of Western countries.

According to Sozanska et al. the hygiene hypothesis has more fathers

In 1970, Peter Preston1 posed the following question: ‘‘Is the atopic syndrome a consequence of good hygiene?’’ If this was the case, he argued that ‘‘the manifestations of atopy . would have appeared in given areas only after standards of hygiene . had been raised to high levels.‘‘

while David Strachan calls  it a misnomer since I know him. The last occasion was in the BMJ in August 2014

As the authors correctly point out, the term “hygiene hypothesis”, which is often attributed to my BMJ 1989 paper, is actually shorthand for a line of argument established much earlier. When presenting my own work, I regularly remind my audience that the ideas presented in the BMJ 1989 paper were inspired by David Barker’s publications on acute appendicitis a year or two before. However, as the authors acknowledge, Barker’s “hygiene hypothesis for appendicitis” was in turn influenced by earlier thinking.
I also recount that the inclusion of “hygiene” in the title of my paper (along with “hay fever” and “household size”) owed more to an alliterative tendency than to my aspiration to claim a new scientific paradigm. What interested me over the subsequent years was how, after initial disdain on grounds of implausibility, the immunological community enthusiastically endorsed the concept of the “hygiene hypothesis” as soon as they had proposed a cellular mechanism to explain it!
[…]
Indeed, the frustration over 25 years of epidemiological and immunological investigation is that so little progress has been made in identifying the biologically relevant exposures which “explain” the frequently replicated epidemiological observations linking allergic sensitisation and atopic disease (inversely) to family size and to “unhygienic” environments such as farming, separately and in combination…

Allergy, Vitamin D Receptor and Parabacteriodes

There was a congress abstract earlier this year by Rachid, Rima A et al. in  Journal of Allergy and Clinical Immunology:  “Food Allergy in Infancy Is Associated with Dysbiosis of the Intestinal Microbiota” where 137 infants (52 food-allergic and 85 controls) were enrolled and differences in fecal microbiota tested between the 2 groups. Food-allergic babies at 1-6 months of age had decreased abundances of genera in Bacteroidetes (Parabacteroides and Alistipes).

Interestingly, a new genome-wide association study of the gut microbiota using two cohorts from Northern Germany identified genome-wide significant associations for microbial variation and individual taxa at multiple genetic loci, including the VDR gene.  To further explore this association, they analyzed gut microbiota data fin Vdr−/− mice, confirming that loss of Vdr in mice substantially affects diversity. A more detailed exploration also showed that VDR consistently influences individual bacterial taxa such as Parabacteroides.

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So, is this a missing link?-Can vitamin D supplementation influence the gut microbial flora? This could explain even other observations. Right now rs7974353 is a rare human intronic SNP with no disease annotation.

Farm life does not prevent from asthma

In most farm children, asthma is not being prevented. And even in those children who might have had a benefit from being raised on a farm, it is not clear where the protection is mediated by: Some biological agent like endotoxin? Some healthy worker effect? Less medical interventions like antibiotics, Caesarean or vitamin D? It looks like other researchers are sceptical too

Others who study the hygiene hypothesis caution that the newly uncovered mechanism does not entirely explain the protective effect of dairy farm life. Drinking unprocessed milk also seems to ward off asthma in kids, points out Gary Huffnagle of the University of Michigan, Ann Arbor—and that effect is unlikely to involve the lung epithelium. What’s more, endotoxin levels are not that much higher on farms than in cities, suggesting “it’s too simple an answer,” says asthma genetics researcher William Cookson of Imperial College London, who thinks changes in living microbial communities in the lungs and gut may be just as important.

On verification

Most recently, I came across of another euphoric hygiene hypothesis review and wonder how this could ever happen. The evidence here is mixed and largely ambiguous.
Probably it would be best to follow some basic journalistic rules as summarized in the online “Verification Handbook for investigative reporting”

As with the verification of user-generated content in breaking news situations, some fundamentals of verification apply in an investigative context. Some of those fundamentals, which were detailed in the original Handbook, are:

– Develop human sources.
– Contact people, and talk to them.
! Be skeptical when something looks, sounds or seems too good to be true.
! Consult multiple, credible sources.
– Familiarize yourself with search and research methods, and new tools.
– Communicate and work together with other professionals — verification is a team sport.

Journalist Steve Buttry, who wrote the Verification Fundamentals chapter in the original Handbook, said that verification is a mix of three elements:

– A person’s resourcefulness, persistence, skepticism and skill
– Sources’ knowledge, reliability and honesty, and the number, variety and reliability of sources you can find and persuade to talk
– Documentation

Is this a retraction of the hygiene hypothesis?

There are news about the hygiene hypothesis.

Home cleanliness resulted only in quantitative reduction of floor dust, which mainly indicates removal of superficial dirt with a rather cosmetic effect. Conventional cleaning does not eradicate microorganisms sustainably, because emptied microbial niches are instantly recolonized by ventilation and living carrier.

Sure. Continue reading Is this a retraction of the hygiene hypothesis?

An epidemic of nonsense

13 € for a paperback, this is “An Epidemic of Absence. A new way of understanding allergies and autoimmune disease”. It is written by Moises Velasquez-Manoff , a journalist otherwise working for the “The Christian Science Monitor”. As his online bio reports “he dreamed of writing novels”. I would wish he would done so.

The outset is rather clear – Velasquez-Manoff wants to find a cure for his own autoimmmune disease. While this may be a legitimate justification for collecting information about a given topic, the method by Velasquez-Manoff is not. At a first glance, it looks like a serious book, well written, interesting facts presented in a coherent manner followed by numerous references. Maybe that made such an impression on the (numerous) positive reviewers. Maybe all the positive reviewers are experienced science journalists that judged by the overall impression plus some common sense plus some specific knowledge. But, Velasquez-Manoff did never hear the other side (on p.310, he even admits who has read and commented on sections of the manuscript: exclusively scientists in favor of the hygiene hypothesis). To recognize that you need to be a scientist – journalists would not notice that.

I compiled a long list the errors but feel now, that it would be too time consuming to write that down here. As far as it concerns me (p. 99) there was no grant to win in Munich as the study Velasquez-Manoff is talking about was a commissioned study. And sorry (p.100) I wrote the full grant application comparing East and West Germany children and did large part of the field study. Furthermore, I am not convinced (p.101) that the East West German differences ever supported the hygiene hypothesis, it is something different. And it was not in 2000 (p.102) that someone published on day care (p. 102), we wrote that already in 1999. Audiatur et altera pars, yea, yea.

Will the bacterial flora protect you from you allergies?

Here is another post as the field seems to progress so fast with a new study on enterotypes of the human gut microbiome from

22 newly sequenced faecal metagenomes of individuals from four countries with previously published data sets, here we identify three robust clusters (referred to as enterotypes hereafter) that are not nation or continent specific.

The 3 clusters are Bacteroides (enterotype 1), Prevotella (enterotype 2) and Ruminococcus (enterotype 3) – no idea if these are under selective pressure from the host (genes!), from enviroment (antibiotics!) or from microbial competitors. When we look, however, at another study published also last week at Science magazine, it seems that at least one cluster has it’s own trick to get the right of residence by synthesizing a symbiosis factor. Continue reading Will the bacterial flora protect you from you allergies?

Tolerogenic effects of vitamin D?

A new allergy study published last month

hypothesized that prenatal vitamin D supplementation could induce tolerogenic DC at birth. To evaluate this hypothesis in an epidemiological setting, we quantified the gene expression levels of ILT3 and ILT4 in cord blood (CB) samples of a population-based birth cohort of farm and reference children.

ILT3/IL4 as a marker of tolerogenic DCs may be justified by data published by Chang but not by newer data Continue reading Tolerogenic effects of vitamin D?

The dirty little secret

A new editorial talks about the dirty little secret of mouse immunology

the striking difference between human and murine sensitivity to LPS toxicity

where humans are 100,000–fold more likely to die of an intravenous dose of LPS. And of course to cite another review on mice and (not) men Continue reading The dirty little secret

Bleach use and allergy

Here is another paper that supports my long-standing view that the hygiene hypothesis may be wrong

We identified 3626 participants of the European Community Respiratory Health Survey II in 10 countries who did the cleaning in their homes and for whom data on specific serum IgE to 4 environmental allergens were available …The use of bleach was associated with less atopic sensitization (odds ratio [OR], 0.75; 95% CI, 0.63-0.89).

yea, it says less not more! And there is another paper that ask about the hygiene hypothesis “Do we still believe in it?”

This has little relationship with ‘hygiene’ in the usual meaning of the word. The term ‘hygiene hypothesis’ is unfortunate, as it is misleading. A better term would be ‘microbial deprivation hypothesis’.

I even think that microbial deprivation is questionable.

Tired of the hygiene hypothesis

A new Thorax review finds

The hypotheses have arisen from a desire to explain epidemiological differences, and those such as the “hygiene” hypothesis had a seemingly corroboratory immunological explanation. However, they have not taken us to the point where we can proudly announce a primary preventive strategy.

I agree with the last statement but have severe doubts on any “immunological explanation” Continue reading Tired of the hygiene hypothesis