For nearing a few year/s now throughout CKD+IF ~  I am noticing an increased pattern of adverse symptoms when consuming oxalate heavy foods. Namely ~  lower mobility pains, flexibility limitations and overall feeling of lower-back encumbrances.

I'd like to share both a database and an online Oxalate consumption calculator (Globalrpx). This is worth mentioning ~ considering it handily calculates the overall footprint. You can find it here.

All you have to do is to set your checkboxes, # of serving/qty's next to each food item and the calculator will provide you an overall result and a rating.

They also have other calculators for convenience - BMI, TDEE (in various formats and formula methods), Protein intakes and (curiously) ~ an entire section dedicated to "Finances".

Oxalate synthesis - from food or from our own?

Endogenously, synthesis can occur as byproducts of general carbohydrate, protein (particularly from aminoacid Hydroxyproline) and fat breakdowns. Altogether, through what is known as Glyoxalate pathway, here the oxidative byproducts from macronutrients eventually form Glyoxylate, thought to be direct precursor to oxalate synthesis especially if it interacts with other known contributor(s) chiefly among them Ascorbic Acid.

Interesting to note that specific Vitamin deficiencies may also precipitate the above pathway. Namely - B1 and B6 deficiencies.

Next, the exogenous factors ~ from high dietary copper and oxalate rich foods.

Unfortunately due to copyright restrictions ~ copying and pasting even within benevolence intent is forbidden.  I instead resort may only share following resources as URLs.

1. St Joseph Hamilton ~ Patient Education Oxalate in Food
   https://www.stjoes.ca/patients-visitors/patient-education/patient-education-k-o/pd-9447-oxalate-in-food.pdf
2. Nutrition Advance ~A List of 112 Foods High In Oxalate (Oxalic Acid)
   https://www.nutritionadvance.com/high-oxalate-foods/#:~:text=Overall%2C%20the%20highest%20oxalate%20foods,%2C%20beet%20greens%2C%20and%20rhubarb.

A good number of Youtube presentations are also plenty. Chief among them are as follows.

Objective questions ~ meet nuanced answers.

So what are the side effects I experience ?

I may only speak from my own N=1.  "Encumbrances", mobility concerns and/or "malaise" are what I clarify as:

• Back pains "heaviness", bi directionals mostly. Either left or right.
• Following from above - the L4/5/S1 propensity to flare (again) on an on/off basis. Manageable, however I shall have to remind myself that Ankylosing Spondilytis is never a "minor problem"; given I still have many years unknown ahead of me.
• Constipations (subjective) but still currently assesing their patterned occurences.

All these indeed sounds minor. But over the years of cycling in and out of very high and very low amount of fibre intakes I can now attest with some degree of confidence that something will happen.

People of course remain free to opinionate my case be it "isolated", "anecdotal" and thus "unscientific". Be that as it may. But do not forget that you your"self" ~ remains an anecdote worthy for your own exploration.

And what foods impact me the most?

I at times, have to partially wave goodbye; or at least greatly reduce consumptions of the following heavily suspect foods:

• Raspberries. What was once glorified low-carb friendly dessert fruits concerned me; such that as just a handful do at times trigger the above symptoms. 
• Black tea. This one is very interesting as I may have to change my stance and opinion on their safety perhaps in the future. I will almost guarantee to feel some encumbrance soon upon drinking it in or outside ~ of my fasting windows.
  • Green tea however appears to be milder, and thus safe(r) thus far from my  experience. 
• Spinach.
• Avocadoes.
• Potatoes. Surprisingly to most home frugalists and health-user-biases, potatoes and sadly sweet potatoes and/or yams (if you are from the other side of the globe). As a result during my carbohdyrate refeed days and/or allowance I'd stick to good ol' rice pudding and/or even just the plain DIY breads and basic cake recipes.
• Cacao and cocoa powders. There is an article here explaining the various oxalate concentrations amongst cocoa and cacao products.
  
• Peanut butters. Sadly and regretful ~ peanut butters have been long admittedly a comfort food amongst LC / low carbohydrate+IF days; and despite their complimentary nutrient profiling that few other plant based sources have, in particular curiosity ~ plant based source of COQ10 ~ I have begun to only consume these on a rotating one week on one week off fashion.

A note on coffees. There appears to be many conflicting and often confusing findings. TLDR; I have been coffee drinker for nearly as long as I have forgotten (at times ) about water. So far I do not think these have any serious impact on oxalate footprint.

I may only recommend you all to please read Sally K Norton's excellent coverage and lengthy self-meta on various reasons why the big discrepancies from one study after another.  TLDR; instant coffees may possess higher amount than that of regular grounds.

How long / how soon do adverse effects began and/or last?

Depending on the quantity of prior consumption and/or food types ~ I am confident to say that malaise or encumbrances may surface within a manner of hours. But on some clearly-suspect items, particularly black tea - as little as minutes upon ingestion.

If there are 24 hours urine test to examine possible kidney health, then such short window of insight ~ should indicate more than enough time for us all to test on our accord whether or not any suspecting food may have an effect.

Usually, abstinence usually resolve all symptoms within the same day or at least until one or two bowel movements. Other things that help mitigate include - regular mobility variations  be it sit/stand stance. And obviously ~ regular training but within mindfulness especially if you are also suspected to have Ankylosing Spondylitis episodical flares ~ and/or suspected with disc degeneration.

Noteworthy reminders about Ca (Calcium) and Mg (Magnesium) role in prevention...

Calcium and Magnesium both are chelators / thus binders with oxalates to prevent the inevitable crystalization in the kidney  (Betz, M. 2022).

Coincidentally ~ Calcium salts (Huynh, H. et al 2020)  and Magnesium (Massey, L. 2005) + (Riley, JM et al. 2013) appear to help offset the risk against hyper oxalate absorption. In particular, that latter study finds that acidic PH, tends to be synergistic with magnesium*. This also coincides with another study that looks at intestinal absorption suggesting that Mg absorption requires acidic medium, alongside a citrate (Schuchardt JH & Hahn A 2017).

*As per from the abstract: "Mg²⁺ inhibitory effect is synergistic with citrate and remains effective in acidic environments." (Riley, JM et al. 2013).

• Whilst it is important to realize again that Mg Oxide is poorly utilized, many of these cheaper Mg supplements (at least throughout Australia) nonetheless come with helpful cofactors and other micro's. Notably Vitamin B6 and Manganese.

A pragmatic takeaway, were I to take for myself is to have both amino acid chelated version and the usual oxide version of Magnesium. These at least, allow the additional micros to be in favourable supply notably Vitamin B6 and manganese serving as methylation support and B6 in protein metabolism. As for Calcium, I still emphasize food sources from dairy for now, alongside my own DIY yoghurts. Once again, I would encourage you to please gather insight upon yourselves adequately first and foremost.

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Conclusion

I only speak from my own N=1 experience. Your's very own nutrigenomics and biology obviously will vary.

By no means I am condoning complete abstinence on all these foods. Many of these ~ namely cacao powders avocadoes, peanut butters still contain elusive and arguably essential minerals and anti-oxidants that are complimentary to everything else.

Irrespective oxalates should be a genuine concern. One must weigh the pros and cons with some personal introspect that at the very least no single food may yet ever be "safe".

My stance when it comes to bargaining with chaos have not changed cycle anything subjective. Years of SKD then Cyclical Keto + IF both indeed have taught me much.

Live-It-Forward,

AW.