How Ultra-Processed Foods May Be Accelerating Knee Osteoarthritis, Especially in Women
Introduction
Ultra-processed foods (UPFs)—think packaged snacks, fast food, and sweetened drinks—have become a staple in modern diets, accounting for nearly 80% of total caloric intake in the typical North American diet. But a new study published in Osteoarthritis and Cartilage sheds light on an emerging and concerning link: higher UPF consumption is associated with worse knee osteoarthritis (KOA) outcomes, particularly in women.
This large-scale cross-sectional study from the Osteoarthritis Initiative (OAI) analyzed over 4,400 participants and is one of the first to connect the quality and processing of foods—not just calories or weight—to the structural and symptomatic severity of knee osteoarthritis.
Study Overview
Researchers from the University of California, San Francisco and several international institutions used detailed food frequency questionnaires to estimate each participant’s daily UPF intake based on the NOVA Classification System. Foods were categorized from minimally processed (NOVA-1) to ultra-processed (NOVA-4).
Clinical, imaging, and physical function outcomes were then analyzed, including:
WOMAC scores (pain, stiffness, and function)
Gait speed and chair stand tests
MRI-measured cartilage thickness
After adjusting for confounders like age, BMI, physical activity, and calorie intake, the researchers assessed how UPF intake related to osteoarthritis symptoms and joint structure.
Key Findings
The results were striking, especially for women:
Pain and Function: Each standard deviation increase in UPF consumption was associated with higher WOMAC pain (+0.17), worse daily function (+0.59), and worse total scores (+0.81).
Cartilage Health: Women who consumed more UPFs had significantly thinner knee cartilage—on average 13 micrometers thinner—as shown on MRI.
Movement Performance: Higher UPF intake was linked to slower gait speed (−0.035 m/s) and fewer repetitions in chair stand tests, indicating poorer lower-body strength and endurance.
Sex-Specific Impact: These associations were significant in women, but not in men, even after controlling for BMI and physical activity.
In short, women who consumed more ultra-processed foods reported more pain, worse physical function, and showed measurable signs of joint degeneration.
Why It Matters
Osteoarthritis already affects over 10% of adults in the U.S., with women disproportionately impacted. While obesity and age are established risk factors, this study suggests that diet quality itself—specifically food processing—may directly influence joint health.
UPFs are typically high in refined carbohydrates, added sugars, unhealthy fats, and additives such as emulsifiers and artificial colors. These ingredients promote chronic low-grade inflammation, metabolic dysfunction, and gut microbiome disruption—all of which have been linked to osteoarthritis progression.
As previous research shows:
Diets rich in whole, unprocessed foods like fruits, vegetables, and olive oil (e.g., the Mediterranean diet) are associated with lower OA severity and slower disease progression (PMID: 30481663, 30502745).
High-UPF diets have been tied to reduced skeletal muscle mass (PMID: 39020709) and higher systemic inflammation.
Muscle loss, in turn, contributes to reduced joint stability and load tolerance—critical factors in knee health.
This aligns with Zero Point One Physical Therapy’s core philosophy: capacity matters. If your diet reduces your ability to build or maintain muscle and control inflammation, your body’s capacity to move—and to protect joints—shrinks.
Why Women Are More Affected
The sex-specific findings are particularly notable. Women already have nearly a 50% lifetime risk of developing KOA, compared to 40% in men. Hormonal changes, differences in muscle mass distribution, and inflammatory profiles may amplify the effects of UPFs on cartilage and function.
The authors suggest several explanations:
Systemic Inflammation: Biomarkers like C-reactive protein and adipokines correlate more strongly with OA-related pain in women.
Body Composition: Independent of BMI, women with KOA have less lower-body lean mass than men, making them more vulnerable to muscle loss from poor nutrition.
Gut Microbiome: Estrogen-sensitive changes in the microbiome may worsen with a high-UPF diet, increasing inflammation and cartilage degradation.
Clinical Implications
This study emphasizes that what you eat is just as important as how much you eat when it comes to joint health.
A few takeaways for patients and clinicians:
Reduce UPF Intake: Replace processed snacks and sugary drinks with whole foods.
Focus on Anti-Inflammatory Patterns: Mediterranean or DASH diets have been shown to reduce pain and inflammation.
Preserve Muscle Mass: Nutrition and resistance training are key to protecting joints and maintaining cartilage health.
Individualized Guidance: Women, especially post-menopausal, may benefit from personalized strategies targeting both nutrition and muscle preservation.
The Bottom Line
A diet rich in ultra-processed foods doesn’t just affect your waistline—it may also accelerate joint degeneration, worsen pain, and reduce physical function, particularly for women. While more longitudinal research is needed to confirm causality, this study reinforces a simple truth:
What you eat today influences how you move tomorrow.
FAQ: Ultra-Processed Foods and Knee Osteoarthritis
1. What are ultra-processed foods (UPFs)?
Ultra-processed foods are industrially manufactured products made mostly from refined ingredients, additives, and preservatives rather than whole foods.
Examples include packaged snacks, sweetened drinks, fast food, frozen meals, and breakfast cereals.
These foods are designed for taste and shelf-life—but they’re typically high in sugar, unhealthy fats, and sodium, while lacking nutrients that support tissue repair and inflammation control.
2. How can ultra-processed foods contribute to knee osteoarthritis?
UPFs promote chronic low-grade inflammation and metabolic dysfunction, both of which can accelerate cartilage breakdown and joint degeneration.
They’re often linked to obesity, insulin resistance, and muscle loss—all factors that increase stress on the knees and reduce the body’s ability to absorb load.
The 2025 Osteoarthritis and Cartilage study (Akkaya et al., 2025) found that individuals with higher UPF intake had worse pain, slower walking speed, and thinner knee cartilage—especially women.
3. Why are women more affected by ultra-processed food consumption?
Women tend to have lower muscle mass and hormonal shifts that influence inflammation and cartilage health.
Post-menopausal estrogen decline can make joints more vulnerable to inflammatory and metabolic stress.
The study found that the negative effects of UPFs on pain and cartilage thickness were significant in women but not in men, suggesting hormonal and body-composition differences play a key role.
4. Can changing my diet actually improve joint pain or osteoarthritis symptoms?
Yes—research consistently shows that improving diet quality can reduce pain and slow disease progression.
Diets rich in fruits, vegetables, olive oil, fish, and whole grains (like the Mediterranean or DASH diets) have been linked to lower inflammation and better mobility.
Even modest reductions in processed foods can improve energy levels, muscle performance, and recovery when paired with resistance training.
5. What’s the connection between diet, muscle mass, and joint health?
Muscle acts as the body’s shock absorber and metabolic engine.
Loss of muscle (sarcopenia) reduces joint stability and increases stress on cartilage.
Ultra-processed diets have been linked to lower skeletal muscle mass (Sun et al., 2024).
Building and maintaining strength through progressive resistance training—supported by high-quality protein and nutrient-dense foods—is one of the best ways to protect your knees and extend movement longevity.
See our related article:
Why Muscle Strength Is One of the Most Powerful Predictors of Longevity.
6. How much processed food is “too much”?
While there’s no universal threshold, the study showed that even a 1 standard-deviation increase in daily UPF intake was associated with worse pain and cartilage health.
A practical goal is to limit UPFs to less than 20–25 % of your total daily calories, emphasizing whole or minimally processed foods for the rest of your meals.
7. What are better food choices for joint health?
Focus on anti-inflammatory, nutrient-dense foods that support muscle and cartilage repair:
Lean proteins (fish, eggs, poultry, legumes)
Omega-3–rich fats (salmon, flaxseed, walnuts)
Fruits and vegetables rich in antioxidants (berries, leafy greens)
Whole grains and healthy oils (olive oil, avocado)
These foods provide vitamins C, D, and E—nutrients linked to slower cartilage degeneration (Joseph et al., 2020).
8. Beyond diet, what else can help prevent or manage knee osteoarthritis?
The best approach combines strength training, mobility work, and progressive loading—not rest.
At Zero Point One Physical Therapy, our 3-Step Process helps patients move from pain to performance by restoring capacity, building resilience, and optimizing strength for long-term joint health.
Learn more in our article:
Strength Training Is Injury Protection: A Foundation for Longevity and Movement Health.
9. Can physical therapy help if my knee pain is linked to diet or inflammation?
Absolutely.
While nutrition affects the internal environment, physical therapy rebuilds the external one—your movement patterns, muscle strength, and load tolerance.
An integrated plan addressing both movement and metabolism can reduce pain and restore long-term function.
10. Where can I learn more about how lifestyle impacts joint longevity?
Explore more from our Functional Longevity Series:
Metabolic Health Starts in Your Muscles
Why Strength Training Makes You a Better Runner—Especially When You’re Tired
Strength Training Is the Missing Link for NYC Runners
Related Research
Veronese N et al. Mediterranean diet and knee osteoarthritis outcomes. Clin Nutr. 2019;38(6):2735–2739.
Sun W et al. Association of ultra-processed food consumption with muscle mass among young and middle-aged US adults. Eur J Nutr. 2024;63(7):2621–2629.
Chen J et al. Dysbiosis of the gut microbiome is a risk factor for osteoarthritis in older female adults. BMC Bioinformatics. 2021;22(1):299.