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The Debate on Oxalates
While many are calling for a ban on oxalate-rich foods, new studies (along with thousands of years of ancient wisdom!) are calling for a reevaluation of the current guidelines. It is true that certain stone-forming segments of the population may be at greater risk of kidney stones from an oxalate-rich diet. However, there are many other emerging factors that are making researchers rethink the oxalate issue.
Oxalates are naturally-occurring plant compounds. They protect the plant from invaders, toxins, and heavy metals by regulating the plant’s uptake of minerals. Oxalates bind to minerals and have a specific affinity for calcium. The foods with the highest oxalate content include amaranth, spinach, taro, Swiss chard, potatoes, beets, almonds, legumes, whole grains, nuts, chocolate, turmeric, and tea to name a few.
In humans, a diet rich in foods with high oxalate levels can result in excess oxalates, which could bind the needed minerals in the body. This ultimately increases the risk of kidney stones and malabsorption. While this is certainly a risk to consider, studies show that such risk does not exist when eating a traditional diet. The DASH diet (Dietary Approaches to Stop Hypertension), which is very similar to the Mediterranean Diet, is rich in high-oxalate foods like nuts, grains, and vegetables. Even so, the risk of kidney stones while eating these diets and cooking traditionally was reduced by 40-50%. Studies on the Mediterranean Diet found a similar, lower risk of kidney stone formation.
In nature, many of the plants that are high in oxalates (like spinach and Swiss chard, for example) are also very high in calcium. The calcium binds to the oxalic acids in the gut, making the oxalates insoluble and headed for the toilet. Making them insoluble means they will not be absorbed in the intestines, protecting against kidney stones and mineral deficiencies. High calcium content in any high-oxalate food will bind to the oxalates in the gut, neutralizing the oxalates’ potential harmful effects.
The nuts and grains naturally occurring in a plant-based diet are also high in potassium, phytates, and minerals. These also bind to the oxalates, which is why folks on a plant-based diet generally have a lower risk of kidney stones than meat eaters.
Tea drinkers are another group of folks that consume high oxalate foods but have a lower risk of kidney stones. Researchers believe that the polyphenols in tea may be the mitigating factor, offering protection from the accumulation of oxalates.
Do High-Oxalate Foods Cause Mineral Deficiencies?
There are some reports that suggest that a high-oxalate diet will bind to the minerals in the body, causing mineral and iron deficiencies. While it is true that oxalates will bind to the minerals, once again, studies show that populations that eat a high-oxalate diet do not have higher rates of mineral deficiencies nor iron deficiency anemias.
A 2009 study compared a group of men that ate a Mediterranean Diet to a control group that ate a standard Western diet. Both diets had the same amount of iron in their food intake. Interestingly, the Mediterranean Diet group had higher levels of iron and ferritin compared to the control. They concluded that the group on the Mediterranean Diet (with the highest oxalate intake) actually had improved iron absorption and prevented iron deficiency.
Numerous studies also show that there are no iron deficiencies in groups that eat a balanced vegetarian diet, which is also high in oxalate-rich grains, nuts, and vegetables.
See also LifeSpa’s Essential Minerals Formula
Cooking Lowers Oxalate Levels
In Ayurveda, it is recommended that foods be slowly cooked for long periods of time. Oxalates are soluble in water, so boiling or steaming high-oxalate foods can significantly lower the oxalate content. In one study, boiling Swiss chard and spinach for 12 minutes reduced the soluble oxalate content by 85 and 87%, respectively. Soluble oxalates are not bound to a mineral and are linked to higher rates of kidney stones. Steaming the same vegetables had a 46 and 42% reduction in oxalates. Lectins, if you are wondering, are also water soluble and significantly reduced by cooking in water.
Cooking lentils on a hot plate for fifteen minutes reduced the oxalate content by 42%. Beans cooked for 45 minutes reduced the oxalate content by 60%. If the beans were soaked overnight and cooked for 2 hours, there was a 40% oxalate reduction in red beans and a 76% reduction in white beans.
The same study showed that eating a plant-based, high-oxalate diet (including a normal calcium intake of around 1,000 mg of calcium each day) can effectively neutralize the potentially harmful effects of the oxalates.
Seasonal Eating and Oxalates
In traditional cultures, food was consumed based on a seasonal harvest. Spinach is harvested in the spring, turmeric in the fall along with the nuts and grains… and most of the high-oxalate vegetables are harvested during the summer months. Nature had a plan to spread out the oxalate-rich foods throughout the year, so there would be little risk of overconsuming or stacking oxalates. Also, as mentioned, high-oxalate foods are naturally mitigated with calcium, potassium, other minerals, and phytates that bind the oxalates, making them insoluble for intestinal absorption and reducing their threat. Seasonal intake of these minerals helps to counteract the oxalate content.
Poor Digestion Increases Risk of Oxalate Sensitivity
While the studies show that the risk of kidney stones is quite low when eating a plant-based, high-oxalate diet, the risks do go up if there is an underlying digestive issue. We must view oxalate issues through the lens of an Ayurvedic rule: 85% of all health concerns stem from a digestive imbalance.
Studies show that an alteration of the gut lining can increase intestinal permeability and increase the risk of calcium oxalate stones. Issues with fat metabolism that suggest liver and gallbladder congestion are also related to an increased risk of kidney stones. Issues with the gut lining and fat metabolism may change the environment of the gut. This disturbs digestion and the microbiome. There are naturally occurring bacteria in the gut that degrade oxalates. They are called Oxalobacter formigenes and they depend on healthy digestion to function.
Having a healthy microbiome and amounts of Oxalobacter formigenes is crucial to oxalate protection. One study concluded that a healthy colony of the bacteria was associated with a 70% reduction in the risk of being a recurrent former of calcium oxalate kidney stones. To repopulate the gut with beneficial bacteria, consider Flora Restore. This is a blend of probiotics that adhere to the gut wall. They create a new stable of permanent microbiome residents that will increase the proliferation of other permanent beneficial bacteria like Oxalobacter. Unlike most probiotics that are transient, colonizing probiotics do not have to be taken long-term.