Trypotophan amino acid is metabolized by a series of chemical reactions called the kynurenine pathway. One product is kynurenic acid (KA), which protects the nervous system, reduces inflammation, reduces tissue oxidation and may even prevent cancer. KA is anticonvulsant and has functions in the gastrointestinal tract. The blood-brain barrier (which blocks passage of chemicals from the blood to the brain) reduces the neuroprotective properties of KA.
KA is elevated in fresh broccoli and bee products, such as propolis, honey and pollen. Potatoes contain some of the highest levels of KA. The herb, St. John’s Wort, is high in KA. A daily dose of St. John’s Wort can contain nearly 34 microg. of KA, similar to the amount found in a 100 gm. serving of potatoes.
The amount of KA in potatoes depends on the variety used, the amount of processing, and length of storage. Longer storage reduces the amount of KA. The researchers studied 16 potato varieties and found that several components of potatoes, including sugars, starches, and vitamin C, degrade with prolonged storage.
Dry weight potatoes contained 0.239 to 3.240 microg./g dry weight of potato. French fries contained 0.100 to 0.646 microg/g dry weight of KA. Potato crisps* contained 0.478 to 0.576 microg./g dry weight. These are all potentially therapeutic doses of KA. The amount of KA declined as much as 96% with prolonged storage. Sweet potatoes had very low levels of KA, and potato flour had very little as well.
CONCLUSION: The authors concluded that the daily diet including potatoes should supply a fairly large amount of kynurenic acid (KA) to the body, with neuroprotective and anti-inflammatory benefits.
NOTES: *Potato crisps are either potato chips or slices of potato about ¼ inch thick which have been baked until brown. They can be flavored with a variety of seasonings, and should be cooked as fresh as possible.
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Summary #924. nutrientmedicine.