Arthritis -- From Myth to Fact - Medical Myths - Harvard Commentaries

As far as we know, each of these statements is untrue. Yet all it takes is sound medical research to transform a medical myth into medical truth.

Arthritis is a good example. There's much we don't know about this disease, including its causes or risk factors. But as we learn more through research, what seems like a far-fetched connection today may turn out to be an accepted risk factor tomorrow.

The following risk factors for arthritis may sound like myths, but there is evidence to suggest they are true.

Recent studies suggest that coffee intake may have an impact on the risk of rheumatoid arthritis (RA). For example:

In 2000, a study found that people who drank four or more cups of coffee each day had an striking increased risk of having an abnormal antibody, the rheumatoid factor, in their blood. This antibody is strongly associated with RA. The researchers concluded that coffee intake may increase the risk of developing this type of arthritis.

A 2002 study of more than 31,000 women in Iowa found that drinking at least four cups of decaffeinated coffee each day increased the risk of developing RA. Women drinking caffeinated coffee had no increased risk while those drinking at least four cups of tea daily had a decreased risk of RA.

A 2006 study of patients diagnosed with RA in Denmark found that high coffee intake (at least 10 cups a day) was associated with a more severe type of RA.

A 2003 study of more than 80,000 women, meanwhile, found no evidence of a link between RA and coffee (decaffeinated or regular) or tea consumption.

These findings are not conclusive. So, we'll need more research to better understand the impact of drinking coffee (or tea) on the risk of RA.

Over the last several years, a number of studies have established a firm connection between smoking and RA:

A 2002 study among women in Iowa (the same group mentioned above regarding coffee intake) found that smoking increased the risk of RA but that former smokers who quit for at least 10 years were not at increased risk.

A 2006 study of people with early RA found that smoking was associated with more joint damage, faster progression of arthritis or more joints affected.

Another 2006 study linked cigarette smoking with a more severe form of RA.

In a study of nearly 15,000 people with RA, smoking cessation was associated with an improvement in arthritis.

Due to these and subsequent studies, smoking is now considered a risk factor for RA.

As good as breastfeeding is for newborn babies, there may be additional benefits for new moms: a reduced risk of RA.

A study in 2004 found that the longer a woman breastfed, the lower the risk of RA.

Another study by different authors published in 2008 came to a similar conclusion. Researchers found that women who breastfed for 13 months or longer had half the risk of RA as women who did not breastfeed. The authors suggested that hormones stimulated by breast feeding may explain the observation.

Women with RA often notice a marked improvement in their joint symptoms during pregnancy. Recent studies bear this out, including a 2008 nationwide study in the Netherlands.

Certain medications, such as methotrexate, can harm the developing fetus so it's fortunate that RA often improves during pregnancy. It often allows women with RA to reduce or discontinue potentially harmful medicines or to change to milder medications that are safer for the baby.

The connection between alcohol intake and gout has been recognized for centuries. However, only recently have other dietary connections to gout been recognized:

A 2004 study that surveyed more than 47,000 men found that eating a lot of meat and seafood increased the risk of developing gout, while eating dairy was protective.

In 2007, researchers in Canada published a study linking long-term coffee intake with a reduced risk of gout.

A 2008 study concluded that drinking fructose-sweetened soft drinks increased the risk of developing gout.

Disease risk and severity may be altered by factors that seem unlikely to matter. Just 20 years ago, the following statements might have been dismissed as myth because none of them were well-established or proven:

Coffee and smoking may increase the risk of rheumatoid arthritis, while breastfeeding may be protective.

Women with rheumatoid arthritis may improve while pregnant.

Coffee and dairy products may lower gout risk while meat, seafood and sweetened soft drinks may increase it.

This just serves to remind us: Before discounting an idea that may sound outlandish, it's important to recognize that high-quality medical research can promote yesterday's medical myth into today's medical fact.

Robert H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.