Rheumatoid arthritis (RA) is one of the most commonly occurring illnesses in women and affects about 1% of the world’s population. This autoimmune disease causes chronic and systemic inflammation in the synovial tissue, pain, bone erosion, progressive destruction of cartilage, and eventually, permanent joint damage.
RA impacts the patient’s quality of life, increases healthcare use, 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 flesh foods consumption and rheumatoid arthritis: a case-control study. Image Credit: Doucefleur / Shutterstock.com
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 an inflammatory response moderator.
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 that which includes dairy and red meat, could aggravate RA due to their pro-inflammatory properties.
As compared to other parts of the world, autoimmune diseases are more prevalent in Western countries, which might be due to their dietary habits. Typically, Western diets consist of a high amount of saturated and trans fats, sugar-sweetened drinks, refined carbohydrates, and low levels of omega-3 fatty acids, all of which increase the risk of RA.
About the study
One 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 no link exists between red meat intake and the risk of RA.
As several studies have provided contradictory findings, scientists in a recent Nutritional Journal study sought to address this issue and determine the exact relationship between meat consumption and RA.
In this case-control study, newly diagnosed RA patients who visited a rheumatology clinic in Isfahan, Iran, were enrolled. All recruited patients were not diagnosed with RA for more than 12 months.
Some of the eligibility criteria for the participants included lack of prior chronic disease, not being pregnant or lactating, no history of food allergies, and no reported alcohol use.
The participants’ diet was assessed through data obtained from a semi-quantitative Food Frequency Questionnaire (FFQ), which included information related to the 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 the socioeconomic status (SES) and demographic features of the participants.
An inverse relationship between fish consumption and RA was reported, whereas a significant association was observed between animal flesh consumption and the risk of RA.
Importantly, a direct link was observed between processed meat consumption and 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 get RA. This finding aligns with previous studies indicating a strong relationship between fish intake and reduced risk of RA.
One previous study revealed that consumption of oily fish significantly decreases the likelihood of developing RA. However, intake of fish oil supplements did not appear to yield beneficial results.
A previous Swedish mammography prospective study revealed women who consume one to three servings of fish daily are less likely to get RA. Scientists believe that fish intake 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 key strengths of this study is the recruitment of newly diagnosed RA patients, which reduces the possible changing of diets since diagnosis.
A key limitation of this study is its small sample size. Additionally, the information on the participants’ dietary intake was self-reported, which increased the possibility of error.
The majority of the participants belonged to Isfahan; therefore, the entire population of Iran was not well represented. Furthermore, the study findings might have been influenced by potential confounders such as genetic factors and stress levels, which were not considered.
The current study strongly indicates that a higher intake of fish and seafood reduces the risk of RA. In contrast, high consumption of processed meat may significantly increase the risk of developing RA. In the future, these results must be validated using a large sample size that represents diverse ethnicity and geographical locations.
- Hatami, E., Aghajani, M., Pourmasoumi, M., et al. (2022). The relationship between animal flesh foods consumption and rheumatoid arthritis: a case-control study. Nutritional Journal 21( 51). doi:10.1186/s12937-022-00800-1.