The subject of spinach, oxalates and kidney stones has confused all of us in the healing professions. Fortunately researchers have now vindicated the instincts of some that dark green leafy vegetables are supremely good for us; despite being labelled for their so-called antinutrients.
Oxalate-rich foods are not the cause of kidney stones; nor do they bind significant amounts of calcium and other minerals in those enjoying a wide spectrum of nutritious meals. If they did all vegetarians would be suffering from osteoporosis and iron deficiency anaemia.
Long the advice has been that those with a tendency to form kidney stones should avoid high-oxalate foods. That means little or no spinach, beets or almonds; neither should they eat legumes, cereal grains nor potatoes.
The theory was that on being excreted from the body oxalates bind with calcium forming kidney stones.
Avocados, berries and citrus too are high in oxalates; in short, in many good foods.
Roughly one in ten people have a tendency to form kidney stones; that advice meant that they should avoid all these good foods that have such strong research backing. They are rich in the fibre that supports the microbiome.
Medical advice was that one in ten people enjoying typical grocery store meals should not eat any of these excellent but rich in oxalate foods; or least only in small quantities.
The happy tum contains an astonishing two kilogrammes of friendly bugs; most commonly known are bacteria, viruses and yeast cells but there are other creatures with strange names like archaea.
They form colonies in the colon, urinary tract and armpit too, for example. Now scientists have established that "stone formers" have a serious imbalance; they have large numbers of inflammation-associated bacteria.
Also stone formers were low in friendly bacteria like F. prausnitzii that feed on dietary resistant starch, forming short chain fatty acids that enhance so-called tight junctions in the colon inhibiting excess oxalate uptake.
They found that Stone Formers harboured a gut with a microbiome containing less diversity; and were notably low in the whole phylum Bacillota and the health-associated Fecalibacterium prausnitzii.
The urinary system of healthy individuals has now been clearly shown to have a microbiome of its own. Escherichia coli and Lactobacillus jensenii were particularly abundant in Stone Formers.
Pyridoxine is required in over 140 biochemical reactions in our bodies, including the detoxification of glyoxylate to the important proteogenic amino acid glycine.
Conversely the typical grocery store diet, high in animal protein and refined carbs but low in fruit and vegetable consumption shifts the microbiome to a predominantly proteolytic state, increasing inflammation; and promoting kidney crystal deposition.
A deficiency of dietary vitamin B6 leads to an increase in oxalate excretion.
Paradoxically by recommending that Stone Formers avoid whole grains, legumes and potatoes because of their oxalate content, doctors were actually worsening the situation; those are excellent sources of vitamin B6.
Urinary samples from Stone Former were also significantly depleted relative to Healthy Controls in vitamin B12 and butyrate biosynthesis.
Butyrate is one of the short-chain fatty acids formed in the gut of those with a happy tum; a diverse and plentiful microbiome along with plenty of dietary fibre for them to feed on.
Clearly the happy tum contains many bacteria that synthesise different vitamins.
There is a strong correlation between oral antibiotics and kidney stones; more than double the risk especially in children.
That could be from prescription medication or from our food; animals in feed lots and cages fed daily with anti-microbials.
The take-home from this profound study of spinach, oxalates and kidney stones is manifold.
Generalised health and in this instance the wellness of the urinary system is utterly dependent on a diverse and plentiful array of friendly bacteria and other species in the gut.
Our experience is that kefir is the simplest probiotic to make in the home environment. Those struggling with the issues of spinach, oxalates and kidney stones should probably be making two or more. Avoid those in supplements which swamp the gut with only a few species, narrowing the diversity.
Unpasteurised homemade wines, beers and meads are other probiotics that will add to the diversity of the microbiome.
Bowel disease, kidney stones and natural probiotics like kefir and sauerkraut have a profound connection.
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