Rheumatoid arthritis (RA) is one of the most common diseases in women and affects around 1% of the world’s population. This autoimmune disease causes chronic, systemic inflammation in the synovial tissue, pain, bone erosion, progressive cartilage destruction, and eventually permanent joint damage.
RA affects the patient’s quality of life, increases the use of health care and affects life expectancy. To date, the exact cause of RA is not well understood; however, researchers have indicated that certain genetic and environmental factors are associated with the pathogenesis of RA.
Study: The relationship between animal meat food consumption and rheumatoid arthritis: a case-control study. Image credit: Doucefleur / Shutterstock.com
background
Previous studies have reported some of the environmental risk factors that influence the progression of RA, including stress, viruses, smoking, and diet. Diet, for example, can trigger RA and act as a moderator of the inflammatory response.
Several studies have reported the contribution of dietary components in modifying the extent of inflammation and disease activity in RA patients. These studies have indicated that an animal-based diet, such as one that includes dairy and red meat, could worsen RA due to its pro-inflammatory properties.
Compared to other parts of the world, autoimmune diseases are more common in Western countries, which could be due to their eating habits. Western diets typically consist of high amounts of saturated and trans fats, sugary drinks, refined carbohydrates, and low levels of omega-3 fatty acids, all of which increase the risk of RA.
About the study
A previous case-control study reported that high consumption of red meat increases the risk of inflammatory polyarthritis. However, another study conducted in China contradicted this result and stated that there is no link between red meat intake and RA risk.
Since several studies have provided conflicting findings, scientists in a recent Nutritional Journal study attempted to address this issue and determine the exact relationship between meat consumption and RA.
In this case-control study, newly diagnosed RA patients visiting a rheumatology clinic in Isfahan, Iran were enrolled. All recruited patients were undiagnosed with RA for more than 12 months.
Some of the eligibility criteria for participants included no prior chronic illness, not being pregnant or lactating, no history of food allergies, and no alcohol consumption.
Participants’ diet was assessed through data obtained from a semi-quantitative Food Frequency Questionnaire (FFQ), which included information related to frequency, type and amount of dietary consumption. Anthropometric data such as body weight, height, body mass index (BMI) and waist circumference were also obtained. The authors also collected data related to participants’ socioeconomic status (SES) and demographic characteristics.
Results of the study
An inverse relationship was reported between fish consumption and RA, while a significant association was observed between animal meat consumption and the risk of RA.
Importantly, a direct link was observed between the consumption of processed meat and an increased risk of RA. Several studies have reported that processed meat intake enhances inflammatory mediators, including C-reactive protein (CRP).
Interestingly, other types of meat, such as red meat, poultry and organ meat, did not show any significant association with the manifestation of RA.
Individuals with a higher intake of fish were less likely to suffer from RA. This finding aligns with previous studies indicating a strong relationship between fish intake and a reduced risk of RA.
A previous study revealed that consumption of fatty fish significantly decreases the likelihood of developing RA. However, taking fish oil supplements did not seem to provide beneficial results.
A previous prospective Swedish mammography study revealed that women who consumed one to three servings of fish daily were less likely to develop RA. Scientists believe that eating fish reduces the risk of RA because of the anti-inflammatory properties of fish oil. They indicated that a complex reaction of other fatty acids also triggers pro- or anti-inflammatory activity.
Strengths and limitations
One of the strengths of this study is the recruitment of newly diagnosed RA patients, which reduces the possible change in diets since diagnosis.
A key limitation of this study is its small sample size. In addition, participants’ dietary intake information was self-reported, increasing the potential for error.
Most of the participants belonged to Isfahan; therefore, the entire population of Iran was not well represented. In addition, the study’s findings could have been influenced by potential confounders, such as genetic factors and stress levels, that were not taken into account.
Conclusions
The current study strongly suggests that a higher intake of fish and shellfish reduces the risk of RA. In contrast, a high consumption of processed meat can significantly increase the risk of developing RA. In the future, these results should be validated using a large sample size representing various ethnicities and geographic locations.
Journal reference:
- Hatami, E., Aghajani, M., Pourmasoumi, M., et al. (2022). The relationship between animal meat food consumption and rheumatoid arthritis: a case-control study. Nutritional Journal 21 (51). doi:10.1186/s12937-022-00800-1.