08 August 2009

Is High Phosphorus Intake in the U.S. Diet Hazardous?

Controversy arises as to whether or not a high dietary intake of phosphorus is hazardous to health because in the U.S. the typical diet tends to be high in phosphorus and low in calcium (1). But although the need for increasing calcium for bone health has been clearly established, reducing phosphorus to re-balance the calcium:phosphorus ratio has not been shown to have any additional benefits (1;2).

Serum phosphate levels, for example, when high can reduce vitamin D formation in kidneys reducing serum calcium (2). But high phosphorus also appears to reduce urinary calcium indicating a reversal of the prior detriment (2). In addition, the kidney is effective in maintaining normal phosphorus balance by increasing excretion of phosphorus when necessary (1).

At this time no research including at least one controlled trial has not found any adverse effect from a diet high in phosphorus at levels common in the U.S. (1;2). The exception is in those with impaired excretion such as those with kidney dysfunction (2).

It is worth noting that because calcium interferes with phosphorus absorption, a higher calcium diet would lower phosphorus intake naturally (1). And when intake of phosphorus is in the form of phytate—which is plentiful in grains, legumes and nuts—it just might be detrimental because phytate can interfere with absorption of minerals such as calcium (1).

Reference List

1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
2. Linus Pauling Institute. Phosphorus. Micronutrient Information Center. Available at: http://lpi.oregonstate.edu/infocenter/minerals/phosphorus/

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