A case-control study found a significant association between higher dietary acid load and increased odds of developing knee osteoarthritis.
Data from 150 newly diagnosed cases of knee osteoarthritis (OA) and 300 age-, sex-, and body mass index–matched controls was analyzed by researchers from Zabol University of Medical Science in Iran. Participants’ dietary intake over the past year was assessed using a validated 168-item semi-quantitative food frequency questionnaire; and dietary acid load (DAL) was calculated based on nutrient content related to acid-base balance.
"As both a risk factor and a potential management strategy, the relationship between diet and [knee] OA has emerged as a critical area of research focus," reported Soudabeh Hamedi-Shahraki and colleagues. “This study demonstrates a significant association between high DAL and increased odds of [knee] OA."
After adjusting for age, energy intake, family history of OA, vitamin D and calcium supplement use, physical activity level, cigarette smoking, and BMI, individuals in the highest quartile of DAL had significantly greater odds of knee OA compared with those in the lowest quartile.
The association remained statistically significant when stratified by sex. Among men, those in the highest quartile had an odds ratio (OR) of 2.52, and among women, the OR was 2.55.
Participants with higher DAL scores consumed greater amounts of meats, whole and refined grains, dietary fiber, saturated fats, and phosphorus, and fewer vegetables and fruits, compared with those with lower DAL scores.
The authors noted that knee OA represents approximately 85% of osteoarthritis cases globally and is the sixth leading cause of years lived with disability worldwide, according to the 2019 Global Burden of Disease Study. In Iran, the condition affects 47.7% of individuals aged 35 to 70 years, with higher prevalence among women.
The mechanisms proposed to explain the association between high DAL and knee OA include increased systemic inflammation and oxidative stress. Prior studies have reported elevated tumor necrosis factor-α and total oxidant status among patients with high DAL scores.
While the findings, published in Scientific Reports, suggest a potential link between dietary acid load and knee OA, the authors cautioned that the case-control design does not permit conclusions about causality. They recommend longitudinal studies to further investigate these associations.
According to the authors, this is the first study to examine the association between DAL and odds of developing knee OA in adults.
They declared having no competing interests.
