Intake of Dietary Fiber Associated with Knee Pain in OA

Though non-steroidal anti-inflammatory drugs are commonly used to treat pain in patients with osteoarthritis (OA), the potential side effects associated with these agents indicate a need for safer alternatives.¹ 

Nutritional interventions may prove to be one such option. In a prospective, multi-center study reported in Arthritis Care & Research, scientists conducted the first investigation into a potential link between knee pain in older adults and consumption of dietary fiber.²

The final sample of 4,470 participants (58% women) with or at risk of developing knee OA, and who were examined at baseline and each year for up to 96 months. Individuals with inflammatory arthritis or knee replacement at baseline were excluded from the study. Participants’ dietary patterns were assessed at baseline using the Block Brief 2000 food frequency questionnaire (FFQ), which asks about the average intake of various foods over the course of the previous year.

Knee symptoms were evaluated with pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline and at each annual follow-up session. 

Participants reported a score ranging from 0 to 4 (no difficulty to extreme difficulty) for each of 5 items: walking, stair-climbing, in bed, at rest, and weight-bearing, resulting in a total score ranging from 0 to 20 (no pain to worst pain).  

According to the results, participants’ demonstrated 4 patterns of knee pain: 34.5% had no pain; 38.1% had mild pain; 21.2% had moderate pain, and 6.2% had severe pain. There was an inverse association between moderate and severe scores and total dietary fiber intake (P ≤.006 for trend). 

Compared with those in the lowest quartile of total fiber consumption, participants in the highest quartile had reduced risk of moderate pain (odds ratio [OR]=0.76; 95% confidence interval [CI], 0.61–0.93) and severe pain (OR=0.56, 95%; CI, 0.41–0.78). Additionally, these groups showed similar patterns with regards to consumption of grain fiber in particular.

“Dietary fiber has been found to reduce body weight, systemic inflammation, and other metabolic risk factors such as blood pressure, LDL and total cholesterol, and improved glycemic control in clinical trials,” said study co-author Zhaoli Dai, PhD, MS, a postdoctoral fellow in the Clinical Epidemiology Research & Training Unit at Boston University School of Medicine.^3,4 

“Because knee OA shares similar metabolic risk factors as type 2 diabetes and cardiovascular disease, and [because] obesity and systemic inflammation play an important role in knee OA, particularly symptom-related outcomes, this may explain the biological mechanisms of the association between fiber and lower risk of moderate-to-severe knee pain,” she told Clinical Pain Advisor.

Dr Dai and her colleagues will further investigate this connection, possibly including a serum biomarker to reflect dietary fiber intake. They are also planning a clinical trial to confirm causality. “Before more confirmative study results, older persons are encouraged to maintain a physical active lifestyle, consume a plant-based diet which contains rich food sources of dietary fiber, and monitor their body weight to have a positive impact on their joint health,” she advised.

Summary and Clinical Applicability

Higher intake of dietary fiber, in the recommended daily range of 25 grams, is linked with reduced knee pain in older adults with knee osteoarthritis.  

Limitations and Disclosures

Limitation: One limitation pertains to the lack of follow-up after baseline regarding participants’ dietary patterns.

Disclosures: The authors report that they have no relevant conflicts of interest.

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References

1. Buffum M, Buffum JC. Nonsteroidal anti-inflammatory drugs in the elderly. Pain Manag Nurs. 2000; 1(2):40-50.
2. Dai Z, Lu N, Niu J, Felson DT, Zhang Y. Dietary intake of fiber in relation to knee pain trajectories. Arthritis Care Res (Hoboken). 2016; doi: 10.1002/acr.23158.
3. Slavin JL. Dietary fiber and body weight. Nutrition. 2005; 21(3):411-418.
4. Ma Y, Griffith JA, Chasan-Taber L, et al. Association between dietary fiber and serum C-reactive protein. Am J Clin Nutr. 2006; 83(4):760-766.