Increased plaque build up on the teeth
Oxalate’s are a part of the diet that people only really start to become aware of when they have kidney stones and are asked to avoid them far more. But I feel that there are signs of oxalate issues before kidney stones that can give us a good indication that they may be an issue, and plaque build up on the teeth is one of them.
High amounts of oxalate’s are found in these foods:
- Tahini, poppy seeds
- Peanuts, hazelnut, cashews, almonds
- Chocolate
- Spinach, chard, mustard greens, collard greens
- Beetroot, potato, sweet potato
- Wheat bran, buckwheat, barley, cornmeal, brown rice
- Rhubarb, Star fruit, Pomegranate, Apricots, Figs, Kiwi
- Matcha
- Blackbeans
- Soya
- Turmeric
Calcium oxalate’s build up can end up on the teeth, people with high oxalate diets were found to have up to 150 times the concentration of oxalic acid or oxalate in the oral cavity by Wahl and Kallee (1994).
The gut regulates oxalate absorption and excretion, and imbalances in gut bacteria causing dysbiosis can increase systemic oxalate levels, potentially contributing to oxalate deposition in the body, including on the teeth. Certain gut bacteria, like Oxalobacter formigenes, break down dietary oxalate’s in the intestines, reducing absorption into the bloodstream. Other bacteria, such as Lactobacillus and Bifidobacterium species, may also contribute to oxalate degradation. These bacteria produce enzymes (e.g., oxalyl-CoA decarboxylase) that metabolise oxalate’s into less harmful compounds like formate and CO₂. A healthy population of these bacteria lowers circulating oxalate levels, reducing the likelihood of oxalate deposition elsewhere, including the teeth. A lack of oxalate degrading bacteria which can be due to the use of antibiotics, poor diet, or gut dysbiosis, increases oxalate absorption.
A healthy gut with a balanced microbiome absorbs less dietary oxalate’s, as bacteria degrade it before it enters the bloodstream. Conditions like inflammatory bowel disease (IBD), leaky gut, or small intestinal bacterial overgrowth (SIBO) also impair this process, increasing the absorption of oxalate’s.
There are other bacteria that can be a factor, oral bacteria like Streptococcus and Porphyromonas can contribute to plaque calcification.
The minerals magnesium and calcium play an important role, calcium in the gut binds dietary oxalate’s to form insoluble calcium oxalate, which is excreted in the stools helping to reduce oxalate absorption. When calcium is low, it reduces this binding ability, leaving more free oxalate’s to be absorbed into the bloodstream. Magnesium also binds oxalate’s in the gut, forming magnesium oxalate, this is less soluble and excreted, though less effectively than calcium oxalate. When magnesium is low it increases free oxalate absorption, elevating systemic oxalate levels. Magnesium supplementation has been shown to reduce urinary oxalate excretion, suggesting a role in lowering systemic oxalate levels. Magnesium deficiency can alter gut pH and disrupt microbiome balance, as magnesium contributes to cellular homeostasis and acid-base regulation. With Oxalobacter formigenes thriving in a slightly acidic to neutral gut environment (pH ~6.5–7). A magnesium-deficient state may create a less favourable pH, reducing bacterial activity or survival. The Dutch Microbiome Project defines factors that shape the gut microbiome in a large population cohort. Nature Communications, 13(1):2047. PMC: 9018709 Gacesa R, et al. (2022). This study examined dietary factors, including magnesium, on gut microbiome composition. Low magnesium intake was associated with reduced microbial diversity and altered short-chain fatty acid production, which influences the gut pH, because SCFAs like butyrate maintain a slightly acidic to neutral pH. Specialised bacteria such as oxalate degraders are sensitive to pH shifts caused by nutrient deficiencies, including magnesium.
Vitamin D deficiency could also be a factor, vitamin D enhances intestinal calcium absorption, increasing available calcium to bind oxalate’s in the gut. Low vitamin D reduces calcium absorption, mimicking a calcium deficiency and increasing free oxalate absorption in the gut.
Calcium, magnesium, and vitamin D work together to regulate mineral metabolism and oxalate handling. Deficiencies in all three will amplify oxalate absorption by reducing gut binding from low calcium, magnesium and impairing calcium availability from low vitamin D.
The oral environment’s pH is influenced by diet and gut-derived systemic factors that affect crystal precipitation. A more acidic environment due to poor gut health or diet may promote oxalate crystal formation in plaque and therefore both oral hygiene as well as gut health should both be considered when plaque is a factor in a health history.
