If we could only get personalized info about our microbiome and how we as individuals process oxalic acid.
The problem with spinach (it can be both good AND bad)
Spinach also contains a substance called oxalic acid or oxalates which can bind to calcium and iron in the body and prevent the body from being able to absorb them. Oxalic acid is a natural substance found in several different plant based foods including rhubarb (its leaves contain very high amounts of oxalic acid), chard, and beet greens.
Oxalic acid does bind to some minerals, making them unavailable for the body to absorb. So if you were to eat large quantities of foods containing lots of oxalic acid on a daily basis, you may end up with some nutritional deficiencies over a period of time—but we are talking weeks to months, though, not just a meal or two.
For some people, the high oxalate levels in spinach can also create an increased risk of kidney stones and joint problems.
Oxalates can accumulate in the body, especially the kidneys. When the oxalates combine with calcium, kidney stones can form. Calcium oxalate is responsible for about 80% of kidney stones as a matter of fact. And this is where spinach gets its bad rap.
Oxalates are not recommended for people who have inflammatory diseases including gout, arthritis, and even vulvodynia. These people have a tendency to have a greater uptake of oxalates and calcium. But for most of us, this should not be a problem, as long as you’re not eating spinach every single day.
In fact, gut bacteria, are thought to play an important role in the oxalate absorption, since some types of gut bacteria break down oxalate, especially oxalobacter formigenes, lactobacillus, and bifidobacteria. And other research has shown absorption of oxalates has to do with the combination of foods eaten during a meal. For example, even if your body has difficulty absorbing calcium from spinach, when eaten at the same time as other calcium rich foods, such as milk or cheese, the calcium from other foods is absorbed with no problems.