Red Meat Intake May Increase Risk of Developing RA

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Genetic evidence supported a causal relationship between diet and an increased risk of inflammatory arthritis as well as a causal relationship between different dietary modalities and types of arthritis, according to research published in Frontiers in Nutrition.¹ Results, such as a positive association between beef intake and rheumatoid arthritis (RA), could be used for the prevention and management of inflammatory arthritis through dietary modifications.

Previous research has shown dietary factors can impact joint symptoms and inflammatory diets can lead to an increased risk of developing certain rheumatic conditions. Additional studies have reported that while diets high in cholesterol, saturated fats, and sugar have increased inflammatory markers, vegetarian and Mediterranean diets have been proven to decrease inflammation.²

“Investigating whether dietary modifications are beneficial for patients with inflammatory arthritis has positive implications for both patients and physicians,” wrote a group of investigators from The First Clinical of Medicine College, Yunnan University of Chinese Medicine, Kunming, China.

To better understand the causal relationship between 9 dietary categories—encompassing 30 types of diet—and inflammatory arthritis, investigators conducted a genome-wide association study (GWAS). Mendelian randomization (MR) analyses were used to identify any associations between diet and arthritis and single nucleotide polymorphisms (SNPs) were screened out through the MR Pleiotropy RESidual Sum and Outlier (MR-PRESSO) test. Investigators chose to use an MR study design as it simulates the process of random group assignment in clinical randomized controlled trials.

The dietary exposures were extrapolated using data from a web-based questionnaire sent to 330,000 subjects of European descent by investigators at the BioBank UK between 2006 and 2010. Information included diet and food preferences among patients aged 40 – 69 years and recruited an approximately even number of women and men. The diet consisted of vegetables, fresh and dried fruits, cheese, cereals, bread, meats—including beef, pork, fish, poultry, and processed meat—and beverages, such as coffee, tea, water, and alcoholic drinks. Vitamin supplements, micronutrients, and salt were also considered.

Four main subtypes of inflammatory arthritis were evaluated: RA, psoriatic arthritis (PsA), reactive arthritis (ReA), and ankylosing spondylitis (AS).

Inverse variance weighting (IVW) showed that beef intake, iron intake, process meat intake, cheese intake, and fresh and dried fruit intake were strongly linked to inflammatory arthritis. Beef intake was positively associated with an increased risk of developing RA (Odds ratio [OR] = 2.862; 95% confidence interval [CI], 1.360 – 6.021, P = .006), while iron intake (OR = .864; 95%CI, .777 – .960, P = .007) and dried fruit intake (OR = .522; 95% CI, .349 – .781, P = .002) were considered protective factors. ReA was negatively associated with processed meat intake (OR = .238; 95% CI, .100 – .565, P = .001).

Whereas fresh fruit intake was positively linked to PsA (OR = 2.528. 95% CI, 1.063 – 6.011, P = .036), cheese intake was negatively associated with the condition, and therefore considered a protective factor (OR = .579; 95% CI, .367 – .914, P = .019). Investigators theorized cheese may be protective because it is beneficial to the musculoskeletal system and can increase bone mass.

The robustness of the causal relationship was proven using the leave-one-out analyses and all exposure data passed the heterogeneity check.

Investigators noted performing the MR analysis on an entirely European population may have limited the generalizability of findings to other groups. Additionally, they were unable to evaluate the effect of dietary factors on arthritis among subgroup populations, such as age, gender, and place of residence.

“This study is the first to investigate the causal relationship between multiple dietary intakes and inflammatory arthritis using MR analysis,” investigators added. “The approach used in this study avoids confounding and reverse causality. Previous studies on diet and inflammatory arthritis have mainly focused on the effects of a single dietary factor. Our study enabled a thorough evaluation of the correlation between various dietary factors and inflammatory arthritis.”

References

1. ^{Wang H, Wu Q, Qu P, et al. Diet affects inflammatory arthritis: a Mendelian randomization study of 30 dietary patterns causally associated with inflammatory arthritis. Front Nutr. 2024;11:1426125. Published 2024 Jul 17. doi:10.3389/fnut.2024.1426125}
2. ^{Tedeschi, SK, Frits, M, Cui, J, Zhang, ZZ, Mahmoud, T, Iannaccone, C, et al. Diet and rheumatoid arthritis symptoms: survey results from a rheumatoid arthritis registry. Arthritis Care Res. (2017) 69:1920–5. doi: 10.1002/acr.23225}