A microscopic clue to EDs?

A new post on the "You Must Be Hungry" blog at Psychology Today looked at the relationship between eating disorders and autoimmune diseases, as well as potential treatments in the form of probiotics (healthy bacteria, like the kind in yogurt). Writes author Shelia Himmel:

Enter NuBiome, a company founded in 2009 to develop therapies, including probiotics (beneficial bacteria) that interfere with disease-causing bacteria found in the gastrointestinal tract, focusing on autoimmune conditions. The company founders all have seen or had family members who got sick with autoimmune diseases. That includes bulimia and anorexia.

"The paradigm's got to change," said Brian Lue, a NuBiome researcher. In a paper he delivered recently, Lue explained how people used to think that stomach ulcers were caused by stress and dietary choices.

...Lue explains, "A normal person with a normal immune system may have a rare event in their intestine and this changes the way the normal bacteria in their gut die and break up into fragments. Their immune system then finds a specific piece of the bacteria that looks like a piece of the insulation on their nerves. Now, when the immune cells find that piece of insulation on the nerves, bad things start to happen. The body's immune system turns against nerve insulation because it "thinks" that they are foreign bits of bacteria. In the process it ends up destroying its own tissue because it confuses body tissue with that of the bacteria. This is what an autoimmune disease is. In the case of multiple sclerosis, the insulation on the nerves is attacked by the person's own immune system."

How does all this relate to eating disorders?

Lue refers to a 2005 paper in the Proceedings of the National Academy of Sciences by Serguei Fetissov, who identified specific antibodies in people with anorexia and bulimia nervosa. These antibodies disrupted the normal hormonal systems of the brain, particularly the part of the brain that is responsible for appetite control and the stress response.

Lue writes, "This seems to correlate with the changes in eating habits that defines bulimia and anorexia. The authors of the study suggested that the autoimmune response could be triggered by pieces of several types of bacteria in the gut mimicking the brain hormones. Pieces of H. pylori, the stomach ulcer bacteria, and E. coli are some of the likely suspects."
I'm a long way from saying that yogurt is some magical cure-all for eating disorders (though I do loves me some yogurt), but the research is interesting.

I had previously downloaded the 2005 Fetissov paper that Himmel mentioned in her blog post, titled "Autoantibodies against neuropeptides are associated with psychological traits in eating disorders," and re-read it for this post. The researchers knew from previous research that people with AN and BN had antibodies to α-melanocyte stimulating hormone (Fetissov et al, 2002), known as auto-antibodies because they were antibodies against "self" proteins, and the authors of the 2005 study note that:

melanocortin peptides involved in appetite control and the stress response. In this work, we studied the relevance of such [auto-antibodies] to AN and BN. In addition to previously identified neuropeptide autoAbs, the current study revealed the presence of [auto-antibodies] reacting with oxytocin (OT) or vasopressin (VP) in both patients and controls.
Which is interesting, when you look at the roles of both oxytocin and vasopressin and consider that difficulties with social relationships and stress, respectively, are pretty common in eating disorders. What is also interesting from this study are the differences in auto-antibody levels in AN and BN. In AN, higher levels of auto-antibodies were correlated with higher scores on the Eating Disorder Inventory-2 (meaning higher levels of ED psychopathology), while in BN the opposite was true: higher levels of auto-antibodies meant lower levels of ED psychopathology, and vice versa. (If I'm reading the statistics wrong, please someone let me know- it's been a long time since I had to puzzle through dense biostatistics jargon.) What this difference ultimately means is beyond me, although I hope more research will look into the subject.

At the end of Himmel's blog post, she mentioned that a NuBiome researcher asked about her daughter's (who had anorexia and bulimia) childhood exposure to antibiotics, and Himmel recalled that her daughter had frequent doses of antibiotics. Granted, so did I, for frequent lung infections aggravated by asthma that left me with a 10-pack-a-day smoker's cough at the age of 6. However, antibiotics were peddled like candy when I was younger, and furthermore, EDs existed long before penicillin. Nor was I able to find any research indicating a link between antibiotics and the onset of eating disorders.

Still, the research is interesting and thought-provoking, and I'm curious to see more. I'm also getting a strange urge to hit the dairy case, so if you'll excuse me...

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Cathy (UK) said...

It's an interesting hypothesis - which could also (in theory) account for some of the similarities between EDs and ASDs (e.g. as originally suggested by Gillberg et al.: approx. 1 in 5 people with severe anorexia nervosa also has an ASD).

ASD traits have been associated with gut function and immune function (as well as having a strong genetic influence). Some people with autism observe an improvement of their symptoms with a change of diet and the exclusion of foods that evoke an immune response.

Even so, I am a little wary of 'nutraceutical' companies that market products which they claim to act in a pharmacological manner. I have undertaken contract research for such companies that were seeking research evidence to support the efficacy of their products - in the hopes of making these products marketable. If these 'wonderfoods' were so efficacious they would classed as drugs and not as a food. I do wonder whether the proposed efficacy of some nutraceuticals are largely a placebo effect.

I guess I would also add - as both a biomedical scientist and cynic, that if we were to correlate something as obscure as lifetime banana consumption with ED symptoms we might find an association - and an association that is probably not a cause-effect relationship.

Furthermore, we know what damage EDs cause to both gastrointestinal function and immune system function. The observations of altered metabolism/function in ED patients could merely be symptomatic of their eating behaviours and/or the body's (mal-)adaptation to ED behaviours.

Amy said...

I'm not actually sure I understand anything I just read, but I'll have to try again later. My mom has MS, and her mom has RA, and a rheumatologist once told me that she'd probably see me sooner rather than later. Thanks for the info!

Peregrine said...

This is not nearly as intellectual a response as this post deserves, Carrie. But full disclosure: I **LOVE** yogurt, to the extent that I can actually chart my descent into anorexia and path back to recovery through the brands and amounts of yogurt I was eating at various times. (Thank you Lucerne for keeping me alive when all I would eat for months, literally, was sugar-free vanilla yogurt. Interestingly, at the time, yogurt was the only thing that felt "good" in my stomach...this study sheds some interesting physiological light on that suspicion, although I'm sure my bias was also obviously psychosomatic.) Yogurt = Comfort Food for me, both past and present. When it was (and still is) scary to eat, it's so comforting to remember how good it is for those osteoporitic bones and yes, how nourishing and soothing it feels in the tummy. I likes my good bacteria.

Also--and this is still a scary goal food for me--here's a moment of applause for the pure deliciousness that is Activia :)

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I'm a science writer, a jewelry design artist, a bookworm, a complete geek, and mom to a wonderful kitty. I am also recovering from a decade-plus battle with anorexia nervosa. I believe that complete recovery is possible, and that the first step along that path is full nutrition.

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