Many environmental factors (diet, hormones, smoking) have been studied to determine if there are things that might increase or decrease a person’s odds of developing a rheumatic disease. Researchers are also trying to determine which genetic factors play a role in these diseases. A very readable article titled What Epidemiology Has Told Us About Risk Factors and Aetiopathogenesis in Rheumatic Diseases, provides some interesting clues to things that might put a person at risk for developing RA.
Environment
Coffee – Some studies suggest that drinking coffee increases people’s risk of developing RA. Other studies show no link. How’s that for a definite maybe! The studies that showed a link say that all coffee is a risk – even decaf. Tea, on the other hand, might provide some protection due to “anti-inflammatory and antioxidative properties.”
Caffeine – An interesting twist on the coffee/tea studies is the idea that caffeine raises the risk of seropositive RA, but has no link to seronegative RA.
Red Meat – The equivocal risk found in coffee is matched when discussing red meat. I’ve often heard that eating red meat increases the risk of RA, and some studies have suggested that this is true. A more recent study, however, found no risk. It’s hard to know what to believe when the scientific studies don’t agree. It would make sense for people with uncontrolled inflammation to experiment with their diet and see what works best on a case-by-case basis.
Smoking – No question here. Smoking increases a person’s risk of developing RA, and it appears that the longer/heavier the smoking, the more severe the RA. Interestingly enough, some studies indicate that this risk is for seropositive RA, but those studies “have not shown an increased risk for seronegative RA.”
Stress – Since it’s impossible to live without any stress, citing stress as a risk factor for RA seems akin to citing life as a risk factor. News flash: those who are alive have a higher risk of developing RA than those who are dead. But seriously, excessive long-term stress does appear to play a role.
Blood Transfusion – This risk factor raises all sorts of questions for me. Is there a problem with the blood supply, or is there something else going on? After all, the previous risk mentioned was stress. There’s definitely stress going on if a blood transfusion is needed. Epidemiology is supposed to adjust for these types of things, but that doesn’t mean it always happens.
Obesity – In addition to all the health problems linked to obesity, add an increased risk of RA. Maybe. It’s easy to find sources that say obesity IS a risk factor for RA, but it’s only listed as a conclusion; I couldn’t find data supporting such a conclusion, nor citations of any studies that do more than list an unsubstantiated conclusion. It’s easy to make obesity a target, but I’d like to see some data instead of broad claims. If you run across something specific, please include a link in the comments section.
Birth Weight – The previously mentioned environmental risk factors are things over which people have a certain amount of control. This one is different. People have no control over what their birth weight was (and very little control over the birth weight of their babies), yet big babies seem to have an increased risk of developing RA. It appears that babies with a birth weight of ten pounds (4.54gk) or more have an increased risk of adult-onset RA.
Genetic Factors
Then there are the genetic factors. We have no control over which genes we inherit – and no control over which ones we pass along to the next generation. There’s an introduction to Human Leukocyte Antigen testing over at Lab Tests Online, and I’ll write more about this in a future post. For now, suffice it to say that having a gene associated with a specific disease does not guarantee that a person will develop that disease.
Comments are always welcome.
∞ itis 
Seems odd, but if I took all of these factors (except maybe stress) into account, both of my sisters should have RA, not me! Well, there you go! 🙂 Laurie
I’ve often wondered if the chemical exposure we’re all faced with these days (I mean, of course, the last 50 years or so) have anything to do with rheuma. Probably not — at least, not more than drinking tea, coffee, alcohol, or the other items on the list — because RA has been around a lot longer than the chemicals in the foods we eat and the air we breathe. I think some of us are simply born with RA latent in the wings, waiting for its moment. For some of us, it comes. Just like for some, the other autoimmune deseases come, like MS or lupus. Luck of the draw. There’s no doubt, however, that living a healthier life is good for you, RA or not. Since there’s really nothing concrete I can blame it on, but I know I feel better when I don’t smoke, don’t drink, and eat mindfully, that’s what I’ll do.
There was a story the other day about tea as a possible factor in RA — drinking more than four cups a day might make a person more likely to get it. heh. Hogwash, I say. If that was the case, wouldn’t the incidence of RA be extremely high in countries where they drink tea more often, like the UK and China? Yet the incidence is no higher there than here.
Anyhoo, I’m nattering on. Thanks for the great post, Socks. 🙂
There was a recent study stating that cases of RA are on the rise – in women, but not men. They speculate it may be due to birth control and changes in the amounts of hormones in the birth control pills. That is where obesity may come in – I think I’ve read something about fat having hormonal effect – which then might affect the hypothalmus-pituatary something-something…..
@Laurie – Exactly. They just don’t know.
@Wren – Healthy practices definitely seem to help. Tea a factor? I agree; incidence should be higher in areas with a high consumption of tea if that were the case.
@Chelsea – I wonder if RA is truly on the rise, or if doctors are getting better at recognizing it. Some of the RA forums (fora?) are full of people who were told for years that there was nothing the matter with their joints, but that they were just depressed. It wasn’t until after they had extensive permanent joint damage that a diagnosis of RA was made. We know from these people that they experienced symptoms, sought help from their doctors, but were not taken seriously and now have to live daily with pain that will never go away. We still have too many cases where doctors don’t recognize RA. Maybe in some areas of the world doctors are getting better at recognizing it, and that’s what’s behind the rise in diagnoses. Just my $.02 fwiw.