Allergic Contact Dermatitis and the microbiome

A reader wrote:

Please could you write further on Allergic Contact Dermatitis and the microbiome? I am convinced there is a clear connection there, and note one article you reference above specifically supporting the same also. Would be very interested in your holistic take on the same, as you have done with POTS and MCAS.

My approach is always to try to keep to the gold standard, studies on PubMed.

Bottom Line

At first look, it looks like medical professionals dealing with Allergic Contact Dermatitis and similar conditions, do not want to deal with the gut microbiome. I call this the “It’s not in my wheelhouse” or “I want to keep into my thin silo” syndrome. There is a nasty situation created by excessive specialization of medicine and medical research.

I hate to say it, but the fastest way forward (and to get relief) may be doing citizen science via This depends on people with Allergic Contact Dermatitis getting appropriate 16s tests (see suitable providers here as well as which ones are most popular here). The site will automatically show relationships once we get 20 or more annotated samples uploaded.

I have added these to the symptom list on the site.

  • Official Diagnosis: Allergic Contact Dermatitis
  • Official Diagnosis: Dermatitis (all types)

Review: Ashwagandha – Withania somnifera

In writing another post, I discovered that I had not included this in my review of adaptogenic supplements. Adaptogenic means something that moderates the impact of stress. Stress is very common with ME/CFS and should not be ignored. The earlier posts were:

Studies from Pub Med

Dosage suggestions (from human clinical studies cited above): 300-600 mg/day

ME/CFS Improving Iron Levels by Probiotics

Low iron levels is a common symptoms for ME/CFS. I recently came across a study on how to improve it with the use specific probiotics.

Bottom Line

Probiotics can increase or decrease iron. Our knowledge is limited. If increasing iron is critical then avoid any probiotic containing L.acidophilus. Make sure that you are taking L. plantarum 299v and L. casei

Moderation of COVID-19

There has been a flood of suggestions over the last year for COVID-19. In general, the suggestions are believers in some cure-all supplements, preaching their gospels. The more responsible one register trials and start (example).

The following are what has studies supporting some speculations.

If you know of any other solid studies, please email or add as a comment.

Acid Reflux/GERD – what is known

A reader asked me about this and I have not had to deal with it but I know it is common. Acid Reflux is also called gastroesophageal reflux disease (GERD). So I am doing a summary of my gold standard sources (a.k.a. PubMed). Internet legends are abundant; I know from prior posts that often they got established from some early study that did not replicate, or was even misread… and the legend just kept going on and on by being repeated. You may also wish to review my 2016 post on this topic

As a statistician, I found the following informative in terms of risk factors (hint: changing some of these habits may improve things.

  • non-Hindu religion (2.4% vs. 1.2% for Hindu) [2021]
  • non-vegetarian diet (15.5% vs. 4.2%) – which explains above nicely [2021]
  • lower socioeconomic class ( 31.5% vs. 20.9%) [2021]
  • carbonated soft drinks ( 72.5% vs. 49.8%),[2021]
  • For US women [2021] “The five factors include normal weight, never smoking, moderate-to-vigorous physical activity for at least 30 minutes daily, restricting coffee, tea and sodas to two cups daily, and a “prudent” diet”
  • “we identified 7 risk factors: overweight/obesity [GERD/erosive esophagitis (EE)/GERD symptom], central adiposity [EE], smoking [GERD], alcohol [GERD/EE/non-erosive reflux disease (NERD)], NSAID [GERD], coffee [EE], Helicobacter pylori eradication [EE], and 1 protective factor: physical activity [GERD], ” [2020]
  • “psychological distress were found to be risk factors for esophageal symptoms on multivariate analysis.” [2020]
  • Rotating night shift work is associated with an increased risk of gastroesophageal reflux disease (GERD) symptoms among workers in China: a cross-sectional study [2020]
  • “GERD is common throughout the world, and its epidemiology is linked to the Western lifestyle, obesity, and the demise of Helicobacter pylori.” [2020]
  • ” The represented logistic regression shows that family history of GERD, marital status (divorce), smoking, physical activity frequency, tomatoes/tomato-based foods, salty foods, acidic drinks, frequent use of analgesics, and nonsteroidal anti-inflammatory drugs (NSAIDs) consumption shows statistical significance and association (P < 0.05) with increased risk of symptomatic GERD.” [2020]
    • GERD takes NSAIDs more than controls
    • GERD eats chocolate less than controls
    • GERD eats Tomatoes/Tomato-based food more than controls
    • GERD drinks more citric drinks than controls
    • GERD drinks more tea than controls
    • GERD drinks less pop than controls
    • GERD smokes more than controls (note: smoking is often associated to stress)
  • Short Meal-to-Bed Time Is a Predominant Risk Factor of Gastroesophageal Reflux Disease in Pregnancy [2020]
  • “Sixty-one per cent of students who had a habit of midnight snack for more than three times a week were having GORD symptoms, in comparison to 47% of who did not have the habit.” [2020]
  • Sixty-one per cent of students who had frequent lack of breakfast for more than three times a week were having GORD symptoms, in comparison to 43% of who did not have the habit”[2020]
  • Sixty-three per cent of students who had inadequate sleep were having GORD symptoms, in comparison to 45% of who had an adequate sleep.[2020]
  • ” High BMI, family history, energy drinks and fried food were found to be statistically significant risk factors (p<0.05) by univariate analysis.” [2019]

Microbiome changes of the month (which acts as a reserve to bacteria in gastroesophageal) have been seen

Salivary microbiome with gastroesophageal reflux disease and treatment [2021]

Additional information on microbiome shifts can be found here:


  • “Most gastrointestinal benefits of probiotics have targeted the lower digestive tract, and limited data regarding the upper digestive tract have been reported, particularly for GERD….The aim of this systematic review was to examine the efficacy of probiotics in alleviating the symptoms, incidence, and severity of GERD in the general adult population, as this has not been done before.” [2020]
    • compared with the placebo, postprandial distress syndrome scores declined significantly with the L. gasseri LG21 intervention (37.5% vs. 17.8%)….the underlying mechanisms of L. gasseri LG21 for improving FD-associated reflux are linked to postprandial effects, involving improved protein indigestion and increased gastric emptying.

Hydrochloric acid (HCL)/betaine/pepsin

This is often suggested on blogging and personal opinion sites. I was unable to find any study supporting it’s use and some studies indicating that with some sub-types, it may make it worst.

  • Nutritional Interventions for Gastroesophageal Reflux, Irritable Bowel Syndrome, and Hypochlorhydria: A Case Report, 2016 – mentioned for Hypochlorhydria but not for GERD and this was a single person report.
  • “Decreased acid sensitivity in individuals with increasing body mass index may play a pathological role in symptomatic modulation of patients with GERD.” [2019]
  • “This study shows that a carbohydrate-free diet and/or highly hypoglycidal diet that is enriched with acid pH foods appears to lead to a decrease in the pH of the gastric contents, thus inhibiting the further production of hydrochloric acid with a reduction or disappearance of heartburn symptoms that are typical of gastroesophageal diseases.” [2018] So less HCL results in an improvement.

Herbs / Bitters / Herbal Tonics

While effectiveness is cited in two studies, only a kampo herbal medicine is explicitly named. It may be worth while to try different traditional digestive bitters (as opposed recently created ones)

Bottom Line

As stated above GERD tend to be a western diet disease (and that has been proposed also for the incidence of autism). In terms of life style, the following suggestions should be considered (all of these items appear to be associated to why GERD developed):

  • Early supper
  • No evening snacks
  • Decrease fat and meat content in the diet
  • No soft drinks, citric drinks or tomato based diet (sorry Pizza lovers!)
  • Increase chocolate – ideally 70% cacao or more
  • Daily exercise for 30 minutes
  • No coffee or tea with caffeine
  • Work on sleep — melatonin may help with this, and also the microbiome
  • Lactobacillus gasseri probiotics
  • REDUCE STRESS in your life — yes, it CAN be done. Stress is a state of mind (move on!).

Thus the whys…

  • Not having your digestive tract EMPTY by bedtime (think of circadian rhythm for digestive system being off)
    • Late suppers
    • Evening snacks
  • High fat and meat content in the diet (takes longer to digest — see above)
  • Soft drinks, caffeine(tea, coffee) citric drinks or tomato based diet (sorry Pizza lovers!) – alters bacteria
  • A lack of exercise (impacts microbiome)
  • Stress (impacts microbiome)
  • Sleep issue
  • Not having a good breakfast (think of circadian rhythm for digestive system being off)

On a bit of a speculative nature, given that the mouth microbiome may be a significant player, altering it may be beneficial. There are three items that I would look at:

There is one other approach worth considering, xylitol gum. There is evidence in a recent 2020 study that xylitol helps, Effectiveness of salivary stimulation using xylitol-malic acid tablets as coadjuvant treatment in patients with gastro-oesophageal reflux disease: early findings [2020]

Special Note for Autism

I have seen several children (and the literature agrees) with (very) high Bifidobacterium level, typically without an identified species. We not that there are both increases and decreases in Bifidobacteriaceae shown below. PPI should be use with caution.

This BMJ article had a nice graphic of what PPI’s do with red dots indictes higher growth and blue dot with decrease.