miércoles, 10 de abril de 2019

Probióticos: ¿sí o no?

El acceso a y uso de probióticos está cada vez más extendido. No solo se venden como suplementos en las farmacias, si no que también lo vemos anunciado en variedad de productos como yogures, té kombucha, miso, kéfir, etc.
Imagen de Bruno Glätsch en Pixabay 

Para aquellos que no sepan de lo que estoy hablando, los probióticos son microorganismos vivos que pueden, potencialmente, aportar beneficios para la salud de aquellos que los consumen (1). Según la Organización Mundial de Gastroenterología, estrictamente hablando, solo se les debería llamar probióticos a aquellos productos que han demostrado, en estudios, producir este efecto beneficioso. 

En general, se supone que al introducir especies de bacterias beneficiosas para el organismo, nos podríamos beneficiar de, por ejemplo, menor incidencia de diarrea tras el uso de antibióticos, ya que éstos matarían tanto a las bacterias dañinas como a las "buenas" que tenemos en el intestino. Sobre el papel tiene sentido, pero en la realidad no ha habido tanto éxito aplicándolo. Por ejemplo, hay estudios (2) que no han encontrado un efecto consistente tras el consumo de yogur para prevenir la diarrea asociada al consumo de antibióticos, e incluso este estudio (3) mostró cómo algunas personas suplementadas con probióticos presentaban un retraso en la recuperación de la flora intestinal tras el uso de antibióticos, comparados con aquellos que tomaron un placebo. Curiosamente, lo que sí que demostró tener un efecto positivo fue el transplante fecal autólogo, que es básicamente la reintroducción de las heces del paciente en sí mismo. 

También se ha sugerido que los probióticos estimulan, modulan y regulan la respuesta inmunitaria del huésped (4) y que podrían jugar un papel importante en la regulación de la inflamación en enfermedades inflamatorias intestinales (5). Incluso jugaría un papel importante en la dermatitis atópica (6).

Sin embargo, existen varios "problemillas" con los probióticos. Para empezar, al ser un suplemento alimentario, no está regulado de la misma manera que los medicamentos, con lo que podría contener especies de bacterias que "no nos interesan" y que podrían ser dañinas (7). También ha habido casos en los que los efectos asociados a estos "suplementos" o probióticos no han podido demostrarse cuando se le ha pedido a la compañía en cuestión que presente los hallazgos o las pruebas que demuestran que en realidad sí que se produce un efecto beneficioso. Este es el caso del Activia de Danone o del L.Casei (8). Básicamente le vinieron a decir a Danone que hasta que no pruebe que el activia te regula el tránsito intestinal y que el Actimel te protege de resfriados (por los probióticos que contiene), pues que no puede decir que sus productos te curan nada de nada. También existe el problema de que el probiótico tiene que atravesar en estómago, con sus ácidos gástricos correspondientes, con lo que las cepas tienen que estar protegidas de tal manera que consigan llegar al intestino. Y luego, una vez allí, tienen que sobrevivir y colonizarlo. 

Y la realidad es que, ahora mismo, no hay suficientes estudios que garanticen que a nivel poblacional sea beneficioso el uso indiscriminado de probióticos. De hecho, hace tan solo unos días, se ha presentado en la reunión anual del American Association for Cancer Research, un abstract que mostraba como en pacientes con melanoma, tomar suplementos probióticos se asociaba con una posibilidad 70% menor de respuesta al tratamiento de inmunoterapia contra ciertos tipos de cáncer. 

La flora intestinal es muy personal, y cada uno tenemos diferentes microorganismos que pueden responder de manera distinta a la suplementación con probióticos. Sí que es un área que promete y que creo que va a tener mucha importancia en los próximos años, aunque los datos parecen apuntar a que los probióticos deberán ser diseñados de forma personal, y que no va a ser algo de que "un probiótico nos vale a todos para todo". También los transplantes fecales (que ya se realizan en España) están cobrando más importancia, ya que en vez de introducir un número limitado de especies, estamos introduciendo un ecosistema completo. 

También mencionar que aunque sí que se ha demostrado su eficacia en casos aislados (9),  existe mucha publicidad dudosa al respecto, como el Probiota Histaminx, cuyos estudios asociados a la eficacia no he conseguido encontrar, cepas de probióticos de farmacia como Lactibiane, que tampoco tiene estudios para demostrar la eficacia (en su estudio no consiguieron probar eficacia en aliviar los síntomas del Intestino Irritable (10): Lactibiane Référence was not superior to the placebo in relieving symptoms of IBS (42.6 % vs 42.3 % improvement).

Muchos de estos probióticos parece que podrían tener efecto. Sin embargo nos hemos liado a crear productos con probióticos sin todavía entender completamente el mecanismo de actuación ni tampoco la complejidad del microbioma intestinal.

Lo cierto es que se necesitan muchos más estudios para conocer qué bacterias, qué cepas dentro de esas bacterias, en qué cantidades, durante cuando tiempo y para qué condiciones/enfermedades los deberíamos tomar. Y, aunque el consejo general solía ser "bueno, tómatelo, daño no te va a hacer y a lo mejor te va bien", cada vez hay más evidencia disponible de que no es cierto y sí podría tener un efecto nocivo.

Parece que además de probióticos y prebióticos hay un tercero que se ha unido a la fiesta, los postbioticos, pero ya hablaremos de ellos más adelante. 


Referencias
1. http://www.worldgastroenterology.org/guidelines/global-guidelines/probiotics-and-prebiotics
2. https://www.sciencedirect.com/science/article/pii/S0899900714005139?via%3Dihub
3. https://www.cell.com/cell/fulltext/S0092-8674(18)31108-5
4. https://genomemedicine.biomedcentral.com/articles/10.1186/s13073-016-0300-5
5. http://www.jimmunol.org/content/196/10/4311.short
6. https://www.ncbi.nlm.nih.gov/pubmed/29117309
7.https://www.consumerreports.org/vitamins-supplements/supplements-can-make-you-sick/
8. https://www.ftc.gov/news-events/press-releases/2010/12/dannon-agrees-drop-exaggerated-health-claims-activia-yogurt
9.https://www.nature.com/articles/nature23480
10. https://www.medecine-nutrition.org/articles/mnut/abs/2007/04/mnut2007434p157/mnut2007434p157.html






lunes, 8 de abril de 2019

Thin Privilege: An Update

After another lively debate on Facebook regarding this topic I spent most of the other night thinking about it and my reaction to it. 
Is this where I suddenly repent and accept my thin privilege? No, it isn't. I still don't like the term, the concept and everything it entails and here is why.
When I read the original article and the comments associated with it it made me angry because deep down I didn't think I was getting any kind of privilege for being thin. Yes as a man, and although I really didn't want to bring race into it, a white man, I fully acknowledge the society we live in has been constructed in my favour. I accept that, and if it will change anything, which I doubt it will, I acknowledge that privilege. 

The comments I received mostly seemed to indicate that I was denying that "weight bias" "body diversity" "Sizeism" and so on existed, which was not the case. What I didn't like was first the assumption that people are "naturally thin", and that my life is easy because I am thin, You have no idea about my life just as I don't about yours, any assumption based on appearance is wrong. 
This point didn't seem to be accepted and I continued to receive anecdotes about people's lives and how they struggle with discrimination, which, at the risk of sounding like a stuck record I didn't deny existed.

After being directed towards research around weight bias and wages, a couple of points jumped out at me and made me rethink why I am reacting this way. 
In an article in the Journal of Applied Psychology (1) it was demonstrated that thinner women get paid more, not surprising, but the opposite was true for men. In fact, larger men get paid more up until the point of obesity. And a quote lifted from an article on Forbes (2) based on the study said. "Skinny men, indeed, are often regarded as nervous, sneaky, afraid, sad, weak, and sick, where men of well-proportioned build are associated with traits such as having lots of friends, being happy, polite, helpful, brave, smart, and neat." 

So is this really "Fat Vs Thin"? Or is it just another example of different rules for men and women?

I started thinking through my experiences in work and the times I've had to say "yes I do eat" or "no I am not addicted to heroin", did me being a thin man (as opposed to just thin) have something to do with this? 
Or the times I felt I wasn't taken seriously in staff meetings. I had always assumed it was because I was one of the youngest in the room (sadly no longer the case) but maybe it was because I was thin? 
While I can still find clothes that fit me in most shops I have noticed that I have had to drop down a size from M to S with no major change in body weight. It appears that provisions are being made to spare men's feelings by simply shifting everything up one size which is not happening for women. So is this really "thin privilege" or just plain old sexism? 
Is it possible that as a man "thin privilege" doesn't extend to me? Or at least not as much as it does for women? 

Rethinking where I stand on this topic I still reject the term thin privilege because I think it diverts away from the real issue which is what society expects of women. It looks like as a man I can put on a few kilos and not suffer any negative consequences, up to a point, whereas women cannot. And to me that is sexism not thin privilege. 

1.  2011 Jan;96(1):95-112. doi: 10.1037/a0020860.
2. https://www.forbes.com/sites/freekvermeulen/2011/03/22/the-price-of-obesity-how-your-salary-depends-on-your-weight/#29a06bbb3d9a

viernes, 5 de abril de 2019

No, we don’t need to talk about thin privilege

 Update: I have modified slightly my opinion on the term thin privilege which can be read here

This is an opinion piece by Wayne Bradley and does not reflect anybody else's views associated with this blog.

Recently I found myself in a debate with fellow nutritionists and dietitians on the Build Up Dietitians Facebook page regarding the concept of thin privilege. Thin privilege is as follows, we “thin” people live in a world where we don’t experience the stigma and prejudices that overweight people experience. We can find clothes easily, we don’t get stared at when we eat in public and so on. 

Ok, so far so good, nobody would argue with that fact. But I have several issues with labelling it “thin privilege”, firstly the word privilege and the tone of the articles I have read regarding this topic indicate that being thin, or “skinny” which gets thrown around lightly but no-one will dare say fat, is something that has been gifted to us, we haven’t earned it and we should thank our lucky stars that we’re in this position. 
Most people, especially those in the health & nutrition industry know only too well how hard maintaining/losing weight is and to hint that normal weight people are somehow blessed or “privileged” is quite insulting, but sadly nothing new. Now of course because I said I eat well and do a lot of exercise that also means I think every large person is bone idle and just eats pizzas all day long! No, it doesn’t! It means making ANY assumption about a person’s body shape is wrong. 

I feel very proud of myself when I see those scales going down, or when I get up 8am on a Sunday to go riding even though the sun is shining and I’d much rather have a few beers with my wife and friends. To suggest I should somehow feel privileged for that completely undermines the hard work and effort I (or anyone) does to maintain their healthy lifestyle. That doesn’t make me unaware of the battles large people go through, in fact, what I do with my life has nothing to do with what my patients do with theirs, which leads me on to my second issue.  

My second issue is also to do with the term “thin privilege”. It is a nonsense term and completely unnecessary. When our patients come to visit us, they will discuss with us the problems they face, not only with their food choices but with self -esteem, health issues and so on. We will listen to them and if we do not share the same problems we will use empathy to understand them and guide our patients through their journey. 
We already have the word, it is empathy, we do not need a new Insta-trendy, buzzword. If as a healthcare professional you are unable to empathise with your patients then may I suggest a career change? Politics perhaps. 

To repeat a previous point, what I do with my life has no bearing on my patient's lives and has no place in a consultation. They are there to talk about their lives not mine. If the boot was on the other foot and my coach was "acknowledging" their superior athletic ability or shall we say "athletic privilege", I would feel extremely patronised and would probably sever ties with that coach very quickly. 

Perhaps I am being too pedantic around terminologies and the use of words. However, I worry that we are going down a particular path where we will not be able to openly discuss weight, obesity and it's related health problems. Body size and shape should not be attributed to attractiveness, I will vigorously defend that there is not one "perfect" type of body in terms of what is "hot" or "sexy". We all have our own tastes and that is what makes the human race so amazing! However, obesity is not healthy, it just isn't. Many co-morbidities exist with obesity, we all know it and not discussing them does not make them go away. 

Saying "you're fat therefore ugly" is disgusting and should be stamped out immediately. But saying "you are overweight and need to make a change to improve your life" is not the same thing and should be what we are saying, but I fear we are becoming too scared of being labelled as "fat shamers". 

To repeat, I acknowledge that larger people have a tough time in regards to the society we live in, but as nutritionists/dietitians we are there to help them and we owe it to them to be honest. What use is saying "yeah I know I'm thin and my life is easier than yours"? 

During the debate, the topic of the genetic influence on body weight continued to appear, while it was beside my original point I will address it here.Yes genetics plays a large role in a person's size. The size of that role varies. However, does that mean we all just give up and say "its the genetics"? Because if that is the case then dietetics is dead!! I don't believe that is the case, some of us have been dealt a good hand in genetics, some haven't. That doesn't mean we can't make the best with what we've got. We can still strive to be the best version of ourselves and I strongly believe that externalising ourselves to the genetically thin and fat does us all a huge disservice. 

Wayne Bradley BSc (hons) MSc PG cert