Scientists seek explanations for the obesity epidemic that is hitting the affluent world: increasingly sedentary lifestyles, junk food, excessive consumption of fast releasing sugars and fructose… or overuse of antibiotics?

I was struck by a sequence of three articles published respectively in 2009, 2011 and 2013, all discussing intestinal microorganisms called methanogens, which produce methane gas. These are very specific microorganisms, which differ from all conventional bacteria, even if all of them share fundamental proprieties that are they are all single-celled organisms without a nucleus.

These intestinal methanogens belong to what is called the kingdom of archaea as opposed to bacteria (in the true sense of the term). Together, archaea and bacteria are what we call prokaryotes. These are fundamentally different to eukaryotes or all unicellular or multicellular organisms characterized by the presence of a nucleus in each cell. Eukaryotes therefore include humans, animals, plants and fungi (multicellular organisms), plus the protists (single cellular organisms with a nucleus, unlike archaea and bacteria).

Methanogenic archaea have recently caught the attention of scientists, especially the Methanobrevibacter smithii species. Its high prevalence in the human intestine was fully recognized in 2009. You can find the relevant scientific reference with slide #47 of the “GI Ecology 1 – Microflora (part 2)” conference on my website www.gmouton.com (see tabs “Conferences” then “Intestinal Ecosystem”).

Two years later, it was the Research Unit on Emerging Infectious and Tropical Diseases at the University of the Mediterranean in Marseille, which informed the medical world that methanogenic archaea are highly resistant to antibiotics. Details of this little known publication (dated 2011) appear on slide #48 of the same conference noted in above. The end result is the progressive selection of methanogenic microorganisms, abundant in the human intestine and resistant to common antibiotics, which leads to their increasing proliferation….

The third article was published on 26 March 2013 in the leading medical journal Endocrinology by the prestigious Cedars-Sinai Medical Center in Los Angeles. You can read the conclusions in slide #49 following the two slides already mentioned. In summary, the authors highlighted a strong link between the presence of the Methanobrevibacter smithii archaea in the human intestine and an increased body mass index (BMI) along with a higher body fat percentage, as this methanogen increases the extraction of nutrients from our food and therefore contributes to weight gain.

Finally, the successive discoveries concerning the Methanobrevibacter smithii, this “bacteria” that is not really a bacteria, merely highlights in humans what we have long understood to be true in farmed animals: antibiotics promote weight gain! This property has been widely exploited to amplify the profits from cattle, to the extent that these practices are now banned in many countries. The use of antibiotics for preventive purposes, really meaning for fattening animals, is finally explicitly prohibited!

However, nobody until now has really wondered about the fate of humans in this regard. Antibiotics use for humans is still being prescribed relentlessly for anything and everything, instead of saving them for serious infections where they play a crucial role. With the overuse of antibiotics we play sorcerer's apprentice in selecting an aberrant intestinal microflora that dramatically increases our capacity to extract calories from our diet. We are indeed changing the course of the evolution of the human species…

Bisphenol-A is today a recognized cause of obesity, especially among girls, as demonstrated by a large Chinese study published on 12 June 2013. This publication was the subject of the article of the month that I invite you to consult on my website www.gmouton.com under the specific heading “Article du Mois”.

This environmental obesogen is found everywhere, from the most diverse plastics (included those used in the manufacturing of bottles and Tupperware), to the inner coating that lines tins and drink cans. The more acidic the content is (peeled tomatoes, fizzy sodas), the more this chemical leaches into our food.

The more you heat plastic (dishes especially made for the microwave, drink containers for tea or coffee, plastic bottles of water coolers, bottled water exposed to the sun in summer) the more contaminated the food or drink will be. There is also bisphenol-A in most thermographic paper and therefore all credit card receipts and department stores receipts: this formidable poison penetrates through the skin and is therefore especially a danger for supermarket cashiers!

Phthalates (especially di-ethyl-hexyl-phtalate or DEHP) have been found to be directly linked to childhood obesity as evidenced by various studies published since 2012, but the phenomenon has been known with regard to adults since 2007. Increased waist circumference, insulin resistance, and type II diabetes: the whole range is implicated!

This family of endocrine disruptors are found everywhere: soft plastic toys for children, dummies, Nutella (from which it was removed in 2012), food containers, medical equipment (gloves, catheters, blood bags), flooring, many cosmetics (deodorants, shampoos, soaps, shower gels, hairsprays, nail polish), stationery (adhesives and glues), shower curtains, tarpaulin for trucks, automobile products, etc. We should not be only wary of DEHP but also of DINP, DIDP, BBP, DBP, DEP, DHCP, DNOP, and DMP: there is something for everyone! There is nothing surprising in this because the lovely name of “fragrance” generally hides the presence of one these dreadful pollutants.

Organotins are a lesser-known family of environmental obesogens, whose unfamiliar names (like tributyltin benzoate or TBT) are also formidable pollutants, highly toxic to many marine organisms, even at infinitesimal doses. Used as “anti-fouling” paint to protect the hulls of boats, and, more generally, various structures and submerged objects, they have cruelly polluted numerous port areas and coastlines. This explains why the use of organotins on boat hulls has been banned worldwide since 2003. It is their capacity to protect surfaces exposed to water due to their biocidal action, which explains why we find them in insecticides, fungicides, acaricides and herbicides. They are still widely used today to protect glass, wood, textiles and also PVC pipes. Their obesogenic action has been demonstrated in animals (mice, frogs), but not in humans, at least not yet.

Dioxins and PCB’s are other endocrine disruptors with complex modes of action that we have already discussed in detail in blogs #24 and 25, due to their deleterious effects on thyroid function. They also exercise an obesogenic effect via other mechanisms, particularly following their attachment to certain nuclear receptors called PPARs. The end result is an increased risk of weight gain (abdominal obesity in particular), metabolic syndrome and even type II diabetes.

Unfortunately for us there are dozens of them! I want to take one last opportunity to devote a blog on the main chemical molecules that have oestrogenic activity and pollute our environment and our food. They are often referred to as “œstrogen-like” or even “xeno-oestrogens”, the latter reflecting the terminology for artificial toxic substances invented by man and named “xenobiotics”.

This is the third time I am discussing this topic, after blogs on endocrine disruptors that contribute to hypothyroidism (blogs # 24 and #25) and obesity (blog #42). These lists may overlap, especially because there is some structural relationship between the different hormones with one or more six-carbon rings. However, each endocrine function can be affected by the action of specific xenobiotic disruptors.

We begin with xeno-oestrogens, which have already been mentioned in the blogs cited above. I invite you to review the discussion on disruptors of thyroid function with regard to polychlorinated biphenyls (PCB’s) and organochlorine pesticides (including DDT), whose chemical structures are strongly reminiscent of these hormones.

Perfluorooctanoic acid (PFOA) is widely present in the coating of non-stick cookware like Teflon; and more generally, it is used as an anti-adhesive in numerous applications. This thyroid disruptor is also known to be a powerful xeno-oestrogen. With its sidekick, perfluorooctane sulfonate (PFOS), it is responsible for the alarming decline of sperm in contaminated men. Their elimination from non-stick cookware is not guaranteed until the year 2015.

Phthalates have already been discussed in the totality of our blogs dedicated to endocrine disruptors. They can cause hypothyroidism and promote obesity and can also mimic oestrogen activity, which is of great concern as they are found in most cosmetic products so readily consumed by women. Also Di-ethyl-hexyl phthalate (DEHP), already mentioned as an obesogen, appears responsible for precocious breast development ("premature thelarche").

Bisphenol–A is known to cause obesity and diabetes, but also has oestrogen mimicking proprieties. It is capable of binding to the œstradiol receptors where it stimulates the formation of ovarian cysts, and most likely contributes to the current epidemic of polycystic ovarian syndrome (PCOS) that now affects so many young women...

Let’s now examine the oestrogenic substances that have not previously been identified as xenobiotics. We start with propoxur (a substance marketed under the name of Baygon) which belongs to the family of carbamate insecticides. It is a matter of chemical structure, with the infamous benzene cycle, which is a source of confusion for hormone receptors. These insecticides are largely utilised in flea and tick collars for dogs, as well as cats. These collars have a dreadful toxicity: think twice before using them!

The same comments can also be made regarding the chemical structure that prevails in propyl gallate, a food additive used since 1948 to stabilize fatty foods, oils, some chewing gum, milk powder, and food packaging for fatty foods, but is now used more in many cosmetics, adhesives and lubricants.

Finally, we conclude with 4-hexylresorcinol, an agent used for its anti-browning property for shrimps and other crustaceans. We also find this oestrogen-like molecule in acne creams, anti-dandruff shampoos, sunscreens, antiseptic mouthwashes, throat lozenges, plasters…

It is critically important for everyone to carefully read labels and to be especially careful with any xenobiotic!

As a first step we must carefully observe the lower part of the neck of patients to detect any suspicious swelling, palpation of which will direct you towards either goitre (hypertrophy of the thyroid tissue) or to one or more nodules. A simple thyroid ultrasound will reveal a lot more, especially with the calculation of the volume of the gland. Each lobe should normally be between 3ml and 9ml: above 9ml is classified as goitre; below 3ml is the opposite, and we are dealing with a hypotrophy of the thyroid gland.

Goitre can reveal hypothyroidism (but beware, as it can also indicate hyperthyroidism) as a consequence of the thyroid tissue being stimulated by the pituitary gland (increased Thyroid Stimulating Hormoneor TSH: see blog #28). Any enlargement of the lobes may be due to a lack of hormone production because it is the body's way to compensate for the insufficient production of the hormones T4 and T3. Careful examination of the thyroid picture often provides valuable information. However, keep in mind that radiologists do not always mention the volume of the lobes or readily consider the volume as being “normal” because they are only interested in the occurrence of goitre and oppositely tend to ignore cases of atrophy. What they call "normal" is in fact the absence of goitre…

Whilst on the topic of general observations, we should also ask the patient to take his/her basal body temperature, which is taken under the tongue in the morning, whilst still in bed, before any activity. This temperature should not go below 36.3⁰C (or under 36.8⁰C around 6PM when generally speaking the maximal temperature is reached). Below 36⁰C, the possibility of hypothyroidism should be explored because the thyroid gland plays an important role in the body as a thermostat. One can also search for "paradoxical" falls in temperature during the course of the day, especially when the patient is feeling cold or unwell…

The time has come to look at the symptoms themselves and detail, to begin with, all the problems arising in the gastrointestinal tract. Let’s be clear at the outset that no patient suffering from hypothyroidism will present all the symptoms at once: sometimes only one symptom is enough to suspect the diagnosis and initiate further investigation. Evidently, the more symptoms and/or clinical signs there are, the more the suspicion grows.

Constipation constitutes a cardinal symptom of hypothyroidism, although it can occur in many other circumstances. We can say without any hesitation that the possibility of hypothyroidism should be explored with any patient suffering from chronic constipation: you may get a low thyroid finding! By constipation I mean no daily bowel movement or hard stools that can only be passed with great difficulty, or result in the feeling of incomplete emptying. In Ayurvedic medicine, the very definition of health includes having one to three well-formed bowel movements daily!

Sometimes we see terrible cases: one bowel movement a week, sometimes every two weeks and even once a month (yes I know that sounds incredible but it does exist). These unfortunate people are prone to colon cancer, or potentially breast or prostate cancer, not to mention gallstones and intestinal dysbiosis in which stasis is a contributing factor. But make no mistake: these patients can also have diarrhoea resulting from mucosal irritation caused by the stagnant stool. It is the only way the body can find to 'pop the cork', but alas constipation will most likely return immediately afterwards.

Indeed, the whole digestive tract can be lazy: we can sometimes see slowed down oesophageal transit or delayed gastric emptying. Patients often mention an abnormally slow digestion with a weight on their stomach after meals. All these claims are supported by scientific evidence and the corresponding slides appear in the conference dedicated to the thyroid gland on my website www.gmouton.com. Refer to the headings “Conferences” – “Functional Hormonology” – “Thyroid” and you can then download for free the file in PDF format or simply view it on line.

We haven’t yet finished with the possible consequences of having an insufficient thyroid function for the digestive tract, underlining that not a single patient can present all the symptoms at once – only one symptom should be enough to make us suspicious!

We have already covered in detail the topic of constipation. However, concerning the slowing of the oesophageal transit and gastric emptying, one must also be aware of their possible consequences: dysphagia and pyrosis (more often called “heartburn”) if the oesophagus has slowed down; dyspepsia, nausea and vomiting if stomach emptying is too slow.

You can also see a significant decrease in the production of digestive juices: less gastric juices, which decrease the secretion of hydrochloric acid in the stomach; less pancreatic juices, which decrease the secretion of digestive enzymes – this is related to the exocrine function of the pancreas as opposed to the production of insulin from its endocrine function.

As a reminder, these links are supported by recognised medical literature, namely articles published in leading scientific journals, available on my website www.gmouton.com under the heading: ‘Conferences” –“ Functional Hormonology” – “Thyroid”.

Let’s now examine the consequences of hypothyroidism on the weight of a patient. Now, all together, you say “weight gain and obesity”… and you would very often be right, but not always, far from it. Indeed, many hypothyroid patients are a normal weight and you can even encounter weight loss or a difficulty recovering any lost pounds. This is explained by a lack of appetite as a direct link between the blood level of T3 (the active thyroid hormone) and that of ghrelin (the orexigenic peptide secreted by the stomach). Laziness of peristalsis, the wavelike contractions that move food through the digestive tract, doesn’t help either. To this must be added the important role of thyroid hormones on metabolism, in particular on bone growth and muscle development. These anabolic hormones are essential for growth, except in case of excess when they become catabolic (wasting caused by hyperthyroidism).

Their anabolic action plays a major part in bone metabolism: it was fully understood from the First World War that bone fractures are more difficult to heal in people suffering thyroid insufficiency. We often speak of the risk of osteoporosis risk in cases of overdose of thyroid hormones (which doesn’t necessarily mean a low TSH!). We don't talk enough about the increased fracture risk in hypothyroid patients. It is however a serious risk as reputable scientific articles can attest (see website).

Let’s now take a look at the many harmful effects of hypothyroidism on the skin, with a significant increase in dry skin, a symptom that is so typical that I often state the following: “any patient suffering from very dry skin – which includes eczema and psoriasis – must be considered hypothyroid until proven otherwise”. That speaks volumes! Childhood eczema or “cradle cap” is also to be included.

The list goes on concerning the potential consequences of autoimmune thyroiditis on the skin: melasma (brown spots on the face), vitiligo (white patches on the whole body), Sjögren's syndrome (loss of tears, dry mucous membranes), premenstrual acne, and hirsutism (excess hair). Do not miss the frequent link with chronic urticaria (I have identified many cases), with the more serious lichen sclerosus, lichen planus, acne rosacea, acne vulgaris, bullous dermatoses, the numerous connective tissue disorders with an impact on the skin, and even with leprosy…