Study rekindles debate over widespread use of phosphorus additives in food

By Maggie Hennessy

- Last updated on GMT

 Phosphorus additives, found in such foods as deli meats, cola, yogurt, prepared frozen foods and soups, are highly absorbed in the gastrointestinal tract. Food manufacturers are not currently required to provide the phosphorus content of foods on pack.
Phosphorus additives, found in such foods as deli meats, cola, yogurt, prepared frozen foods and soups, are highly absorbed in the gastrointestinal tract. Food manufacturers are not currently required to provide the phosphorus content of foods on pack.
A new study showing a correlation between high dietary phosphorus intakes and increased all-cause mortality has reignited the debate over the extensive use of phosphorus additives in packaged foods.

The study, published last week in the American Journal of Clinical Nutrition​, found that high phosphorus intake was associated with increased mortality in a nationally representative, healthy US population. 

“Because of prevalence of high phosphorus intake in healthy adults ​[more than one-third of Americans reported phosphorus consumption that exceeded 1,400 mg per day, the study found] and the widespread use of inorganic phosphorus additives in processed food, our findings may have far-reaching public health implications,”​ wrote the authors.

For the study, exposure to dietary phosphorus was assessed between 1988 and 1994 in a nationally representative sample of 9,686 healthy US adults aged 20 to 80 years with normal kidney function.

All-cause and cardiovascular mortality was assessed through Dec. 31, 2006. The study found that high phosphorus consumption was associated with increased all-cause mortality at amounts exceeding 1400 mg per day, which is twice the US Recommended Daily Allowance for adults. (There was no significant association between absolute phosphate intake and mortality below this threshold.)

Since the study was observational, “we cannot prove that reducing phosphorus intake would reduce risk of death,” ​co-author Alex R Chang, MD, MS, clinical investigator at Geisinger Health System, told FoodNavigator-USA.

More research is needed to understand the health effects of phosphorus intake. We also need more studies understanding the contribution of phosphorus in food additives to our diets.

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Commonly used to enhance flavor and preserve food, phosphate additives are as ubiquitous in our food supply as sodium.

Dietary intake, not just blood levels of phosphate, linked to adverse outcomes

While phosphorus is an essential nutrient for cell structure and function found naturally in some foods such as dairy, meat, fish, eggs, nuts and legumes; intakes have increased in recent years as more inorganic phosphates are added to packaged foods in the form of phosphorus additives used as anti-caking agents, to help preserve moisture or color, as stabilizers, leavening agents and acidifiers.

And a growing body of research has linked elevated serum phosphate levels to higher mortality in people with chronic renal failure and increased risk of cardiovascular disease in healthy people.

"This is a very important publication with some potential implications for public health policy,"​ Geoffrey Block, MD, director of clinical research at Denver Nephrologists, told FoodNavigator-USA. 

"While we have known for some time that elevated blood levels of phosphate were associated with increased mortality and increased likelihood of developing kidney disease, and we've known that the amount of phosphate in the diet is likely to contribute to these outcomes, one of the critical pieces of information that has been missing has been solid evidence that dietary intake of phosphate per se, and not just blood levels of phosphate, are clearly linked to adverse outcomes."​ 

“We have long seen this correlation in the population of persons with kidney disease, but only recently has this been recognized as an issue applicable to the general population,” ​added Janeen Leon, MS, RD, LD, a dietician and researcher at MetroHealth Medical Center in Cleveland, OH. 

​[The Chang et al] findings are worrisome because of the broad use of phosphorus-containing food additives in a large proportion of foods sold in the United States.”

Not difficult to eat a diet high in phosphorus, even if we think we are eating healthy

Leon co-authored a recent study​ in the Journal of Renal Nutrition​, which found that nearly half (44%) of the best-selling grocery products in the US contain phosphorus additives, based on a sample of product labels from 2,394 top-selling branded grocery items in northeast Ohio.

The additives were especially common in prepared frozen foods (72%), dry food mixes (70%), packaged meat (65%), bread and baked goods (57%), soup (54%), and yogurt (51%) categories.

“It is not difficult to consume a diet high in phosphorus, even if we think we are eating ‘healthy’,” ​ Leon said, adding that even some beverages contain “surprising” levels of phosphorus additives.

"It is widely known that the reference database used in ​[the Chang et al] study and in many others underestimates dietary phosphate intake probably by at least 25-30% due to the use of food additives which are not accounted for," ​Dr. Block noted. "For some food products it is probably 100% of an underestimation."

Dr. Chang added that the source​ of phosphorus is particularly important, "as​ bioavailability is higher in animal-based proteins than many vegetable-based proteins, which often contain phytate-bound phosphorus that is absorbed less. Phosphorus-based additives are commonly used for multiple purposes including improving taste, texture, and reducing cooking time and may be absorbed even more readily than naturally occurring organic sources of phosphorus.”​ 

A wake-up call for the food industry

Despite that, more research is needed to know the contribution of phosphorus-based additives to the average American’s diet, Dr. Chang says that transparency from food manufacturers offers a step in the right direction.

Phosphorus-based additives are important for the food industry for many purposes. However, I think it would be helpful to provide information about phosphorus content in products, particularly for patients with kidney disease who have problems excreting phosphorus,”​ he noted.

Leon added that food manufacturers should also try to decrease their use of phosphorus additives, though this may not be a desirable option, given its moisture retention, flavoring and leavening properties.  

“If manufacturers do not wish to reduce their use, then they should voluntarily quantify phosphorus content on the food label so that consumers can make purchasing decisions with knowledge,” ​she said. “A few manufacturers are starting to list this information on their websites and/or directly on the food label and that is appreciated. Ideally, technologies will fully develop to allow the differentiation between inorganic phosphorus from additives from phosphorus naturally present in the food.”

Dr. Block added: "I’m afraid this won’t be enough to move us fully towards trying to get phosphate content on food labels, but it should be a tremendous wake-up call to the food industry that we are headed that direction and we are continuing to generate the scientific data supportive of the need for full disclosure of phosphorus content in our food." 

Source​: American Journal of Clinical Nutrition

Nov. 13, 2013 doi: 10.3945/​ajcn.113.073148

“High dietary phosphorus intake is associated with all-cause mortality: results from NHANES III”

Authors​: Alex R Chang, Mariana Lazo, Lawrence J Appel, Orlando M. Gutierrez and Morgan E Grams

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2 comments

Phosphorus (synthetic, natural, acids & salts)

Posted by Cassie,

Phosphorus is naturally found in organic foods the highest concentrations are in flax seed, whey proteins and guess what since I was a child grocer shelves didn't stock large quantities supposed health fortified foods. (whey protein diet shakes or meal replacement bars) what I've called bogus health garbage.

Synthetics are your phosphates used in detergents and cleaners work effectively in hard water. Are known pollution contaminate in streams, rivers, marshes, bays and oceans. They alter the PH levels so highly used agricultural fertilizers but in concentrations increase algae including a form that dies causing dead water or oxygen depletion zones as well increase rise bacterium that kills aquatic life or make them poisonous (paralytic shell fish) toward human consumption. Oddly only 16 states ban phosphates that can end up contaminating our water systems other states not banning what's wrong with you? Plus they're used as preservative agent in raw mets to prevent spoilage as the PH altering properties inhibit bacteria but also found in toilet bowel cleaner or surface disinfectant that inhibit germs on surfaces. Being sarcastic here why do people want consume toilet bowl sanitizer or prefer share their pet dogs choice in drinking from the toilet?

Phosphate Salts just as phosphates change the PH levels so too the salts that are used in leavening agents in baking versus use of natural yeasts. They also a used as colon, bowel cleaners or laxatives then the common use soft water treatment systems. The salts are in many health food supplement colon cleanses for health, leavening agent as baked goods for longer shelf life as again PH balance prolongs baked goods these same leavening agents increase aluminum absorption in the body that has been hinted in Alzheimer's disease as those suffering have higher concentrations aluminum in the brain.

Phosphorus acids they give sodas that sharp flavor now citric acid can do the same but it breaks down faster again shelf life also it works as a preservative through PH levels decrease growth molds. This said there is food grade and industrial Phosphorus acids the commercial is used to remove: rust, mineral deposits, and medicinal to dissolve kidney stones or even a preservative in some antibiotics. Again the most common use I've seen is acid wash decks, walkways, remove moss off roofs, power wash mildew off siding, remove rust, descale hard mineral deposits in pipes. Don't believe next time your car battery connections need cleaning to remove corrosion acid scale a little soda pop like coke can fizz it off real fast let alone dissolve the calcium in teeth or calcium kidney stones....What's upsetting concentrations through home improvement grounds keeping supplies to tidy your deck or etc again gets in the water systems.

These concentration are more than food consumption but environmental contamination back into the food supply---I've noticed all the chemical conveniences over use to clean, have food last longer for profit, lose weight without exercise or etc we are getting sicker being lazy! As 40 years ago the ratio population to disease was lower then it is today. As a child I knew more 80+ year old active and childhood cancers let alone cancer occur between ages 2 and 55 as mythical as unicorns. Even obesity s rare it didn't exist unless you were over age 55???

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Phosphoric acid in cola drinks

Posted by Stefan,

To show just how the phosphoric acid in cola drinks degrades teeth, I have made a short film showing the degrade during a whole year:
http://www.youtube.com/watch?v=eaDiWJIGe2U

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