Osteoarthritis (OA) is the most common joint disorder in the United States, affecting over 32.5 million US adults. It’s the most common musculoskeletal condition seen in any medical practice. Most of the patients are aged 60 or older. Painful knee arthritis, for example, occurs in 10 percent of men and 13 percent of women over age 60.
Traditionally, the causes of OA are older age, female gender, being overweight or obese, repetitive use, weak muscles, and knee injury. The standard treatment consists of recommending weight loss to relieve loading on the joints and exercise and physical therapy to improve muscle strength. NSAIDs are often prescribed to relieve inflammation and pain, creating an increased risk of gastrointestinal tract injury, including leaky gut syndrome.
To the causes and treatment of OA, we now need to add the gut microbiome.
The Gut-Joint Connection
Like the metabolic syndrome and obesity, osteoarthritis is characterized by low-level overall inflammation as well as joint inflammation. People with one or more of these conditions usually also show high levels of lipopolysaccharides (LPS) in their blood. Also known as endotoxin, LPS is released from the outer cell walls of gram-negative bacteria when they are destroyed in the digestive tract. LPS escapes into the bloodstream when the tight junctions of the intestinal wall open due to leaky gut syndrome, causing systemic inflammation through the inflammasome NLRP3. (An inflammasome is a protein complex that triggers the proinflammatory process.) Among other impacts, LPS causes joint pain and cartilage degradation.
Recent research suggests that LPS-driven inflammation might be a critical hidden risk factor for OA. In combination with inflammatory mechanisms from metabolic syndrome and obesity, LPS is a double hit to the body. The resulting inflammatory response targets the joints.
Inflammation from LPS indicates an unbalanced gut microbiome, with too many harmful bacteria releasing endotoxins. The functional medicine approach of looking at systems is beneficial for fixing gut dysbiosis. Better diet, prebiotics and probiotics, and more physical activity can shift the balance away from the LPS-producing bacteria and back toward a more diverse array of gut bacteria. When LPS-induced inflammation is reduced, joint pain is usually reduced as well.
Antibodies to gluten, a protein found in wheat, rye, and barley, are another significant driver of inflammation and OA. Gluten is two proteins bound together: about 30 percent is glutenin, and about 70 percent is gliadin. People with celiac disease (CD) have an autoimmune response to both gliadin and glutenin; the response damages the villi of the small intestine and causes systemic inflammation. The inflammation is the root cause of autoimmune arthritis that often develops in people with celiac disease—they are four times as likely to have arthritis as people without celiac disease. A gluten-free diet reduces not only celiac symptoms but also joint inflammation.
People who are allergic or sensitive only to gliadin—non-celiac gluten sensitivity or NCGS–don’t have damage to the villi, but they may have similar digestive symptoms and inflammation that leads to joint pain and osteoarthritis.
Celiac disease is usually seen as genetic, but recent research suggests that gut dysbiosis may have a significant role in the development and possible treatment of both celiac disease and non-celiac gluten sensitivity. Levels of the beneficial Bifidobacterium tend to be low in people with CD and with NCGS, for example.
For some people with either condition, raising the level of beneficial bacteria in the gut may improve gluten tolerance, support a strong gut barrier, and reduce inflammation. Probiotics alone may not be enough—a study that gave Bifidobacterium supplements to volunteers with celiac disease found they didn’t help. While it’s possible that probiotics would be more helpful for NCGS, avoiding foods with gluten and improving the gut microbiome through diet may be more effective. A high-fiber, plant-based diet with fermented and prebiotic foods, along with a prebiotic supplement, is a good approach.
Osteoarthritis can also be driven by lectins and agglutinins, sugar-binding proteins found in all plant foods. They’re especially abundant in beans, peas, lentils, peanuts, nightshade vegetables such as tomatoes, and grains, including wheat, barley, quinoa, and rice. Wheat germ agglutinin (WGA) is found in wheat.
In sensitive individuals, lectins and WGA cause digestive upsets, including bloating, vomiting, and abdominal pain. The damage can be more severe in some cases. The lectins and WGA may bind to receptor sites on the intestinal mucosal wall and trigger leaky gut syndrome and dysbiosis. They may also be another hidden cause of osteoarthritis. The lectins enter the bloodstream through open tight junctions and bind to cartilage and connective tissue, causing inflammation that leads to osteoarthritis.
Because lectins are found in almost all plant foods, they can’t be eliminated from the diet. The damage can be reduced or eliminated by avoiding high-lectin foods such as red kidney beans and thoroughly cooking all beans and legumes. Sensitive individuals may need to cook other high-lectin foods before eating them
Restoring the Gut Microbiome
LPS, gluten, and lectins all cause severe disruption to the gut wall and the gut microbiome, causing leaky gut syndrome and dysbiosis. Although the cause is different in each case, the result—systemic inflammation causing joint pain and osteoarthritis—is the same.
Functional medicine excels in tracing inflammation upstream to find root causes, an approach that will often uncover a hidden cause of joint pain and osteoarthritis. If a problem such as gluten intolerance is discovered, dietary changes to eliminate the source are just the first step. Fixing the leaky gut and restoring balance to the gut microbiome is essential.
As the great Dr. Vladimir Janda once said, “He who treats the site of pain is lost.” Nothing may exemplify this more than the gut to joint connection.
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