Processed foods potassium supplementation

L-ascorbic acid (AA) and L-dehydroascorbic acid (DHAA) are the two main C vitamers occurring in nature [1]. In food analysis, the valuation of the vitamin C total content should account for both forms, since DHAA is readily reduced to AA in the animal body. D-isoascorbic acid (D-IAA), also known as erythorbic acid or D-araboascorbic acid, has analogous reductive properties but only 5% of the antiscorbutic activity of L-AA this epimer is a by-product of vitamin C, and is approved within the European Community as an antioxidant additive [62]. The capability of LC to distinguish the two ascorbic acid isomers and their primary oxidation products is very useful for analyzing processed foods. Forms used for supplementation are AA, sodium-, calcium-, or potassium-L-ascorbate and L-ascorbyl 6-palmitate [4]. 

In unprocessed foods, potassium occurs mainly in association with bicarbonate-generating precursors such as citrate and, to a lesser extent, with phosphate. In processed foods to which potassium is added and in supplements, the form of potassium is potassium chloride. In healthy people, approximately 85% of dietary potassium is absorbed. Most potassium (approximately 77-90%) is excreted in urine, whereas the remainder is excreted mainly in feces, with much smaller amounts excreted in sweat. Because most potassium that is filtered by the glomerulus of the kidney is reabsorbed (70-80%) in the proximal tubule, only a small amount of filtered potassium reaches the distal tubule. The majority of potassium in urine results from secretion of potassium into the cortical collecting duct, a secretion regulated by a number of factors including the hormone aldosterone. An elevated plasma concentration of potassium stimulates the adrenal cortex to release aldosterone, which in turn increases secretion of potassium in the cortical collecting duct. 

End uses of phosphoric acid are highly dependent on the process used to produce it. About 875,000 tonnes (as P2O5) of furnace phosphoric acid was produced in the U.S. in 1984, about 7% of the total U.S. production [70]. Nearly half of this furnace acid is still dedicated to the production of sodium, potassium, and calcium phosphates for use in detergents and commands an 80% or so price premium over fertilizer grade, wet process acid. A further 5% is destined as a food-grade product, which is mostly used as salts in foods, bakery goods, and soft drinks. Some of this grade is also used as a supplement in animal feeds. These are relatively all small-scale uses. 

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