If you have knee arthritis, I’m sure you’ve been told that you should lose weight. For decades, we’ve assumed that arthritis is caused from “wear and tear” and is just caused by repetitive mechanical loading. So if you’re overweight, the joints take on more compression, eroding cartilage faster. But are we sure that is all that is going on? 

If mechanical compression causes arthritis, then how do we explain the piles of evidence that running is good for your knees, not bad. When it comes to research, there are varying degrees of evidence. Randomized controlled trials (RCTs) are pretty top notch, but even better than that is a systematic review. This means that all of the RCTs on a certain topic are summarized. A 2011 systematic review (Urquhart et al.) on physical activity and knee joint health found that “physical activity is beneficial, rather than detrimental, to joint health”. They go on to say that physical activity is also associated with an increase in cartilage volume (yes, increase) and a decrease in cartilage defects.

We do see that when someone loses just 10% of their body mass, they experienced significant pain resolution or reduction, reduced inflammation, and improved function (Messier et al., 2013). We have assumed that it just decreased mechanical compression, but are we sure? 

We also know that diabetics, who tend to have high glucose concentrations, are at high risk for early onset arthritis. In 2016, (Courties & Sellam) published an article that surmised that low grade inflammation and the induction of oxidative stress and cytokines contribute to joint related pain. 

When sugar is in close proximity to a protein, it attaches to it. This is a process known as glycation. This is what is being measured in a HbA1c test. Once the protein is glycated, it changes to advanced glycation end products (AGEs). These AGEs are able to crosslink proteins and cause collagen stiffness. This leads to tissue remodeling and degradation (Degroot et al., 2014).

The good news is that this goes both ways. A low carb, high protein diet can improve tissue remodelling of the extracellular matrix and improve tissue quality. An RCT published in 2019 (Strath et al.), found that low carb diets are more effective than low fat diets in reducing pain intensity from knee arthritis.  

I intentionally chose the picture for this article to include table sugar and strawberries. This is because when I say sugar, I really mean carbohydrates. That is glucose, sucrose, galactose, fructose, etc. Now I don’t mean to vilify carbs, but it is well known that the average Americans consumes an over abundance of carbs, partly because we have been told for decades to “carb up”. Still to this day, dietary guidelines are still heavy on the carb portion. Some of the current ideas behind new diets like the carnivore diet, is to eat like our ancestors. If you think about it, our ancestors didn’t have fruits and vegetables around all the time, and their diet was mostly meat-centric. Not to say that fruits and vegetables are bad, rather we probably take in more than our ancestors did. 

So the next time your achy knee acts up, instead of rushing out to get an injection or swallowing some anti-inflammatories, try cutting back on the carbs for a week. It may be all that you need. 

References:

Courties, A., & Sellam, J. (2016). Osteoarthritis and type 2 diabetes mellitus: What are the links? Diabetes Research and Clinical Practice, 122, 198-206. doi:10.1016/j.diabres.2016.10.021

Degroot, J., Verzijl, N., Wijk, M. J., Jacobs, K. M., El, B. V., Roermund, P. M., . . . Lafeber, F. P. (2004). Accumulation of advanced glycation end products as a molecular mechanism for aging as a risk factor in osteoarthritis. Arthritis & Rheumatism, 50(4), 1207-1215. doi:10.1002/art.20170

Messier, S. P., Mihalko, S. L., Legault, C., Miller, G. D., Nicklas, B. J., Devita, P., . . . Loeser, R. F. (2013). Effects of Intensive Diet and Exercise on Knee Joint Loads, Inflammation, and Clinical Outcomes Among Overweight and Obese Adults With Knee Osteoarthritis. Jama, 310(12), 1263. doi:10.1001/jama.2013.277669

Strath, L. J., Jones, C. D., George, A. P., Lukens, S. L., Morrison, S. A., Soleymani, T., . . . Sorge, R. E. (2019). The Effect of Low-Carbohydrate and Low-Fat Diets on Pain in Individuals with Knee Osteoarthritis. Pain Medicine, 21(1), 150-160. doi:10.1093/pm/pnz022

Urquhart, D. M., Tobing, J. F., Hanna, F. S., Berry, P., Wluka, A. E., Ding, C., & Cicuttini, F. M. (2011). What Is the Effect of Physical Activity on the Knee Joint? A Systematic Review. Medicine & Science in Sports & Exercise, 43(3), 432-442. doi:10.1249/mss.0b013e3181ef5bf8