Phosphoric Acid

At a glance

Also calledE338, orthophosphoric acid, H3PO4
H3PO4, E338, orthophosphoric acid, phosphoric acid E338 (cola acidulant)
Typical doseAbout 50 to 100 mg of phosphorus per 12 oz cola
Not a nutrient with a beneficial dose — a food-acid/flavoring additive. Colas typically deliver roughly 50-100mg phosphorus per 12oz serving via phosphoric acid (context cited in Tucker et al. 2006).
Upper limitNone set — total phosphorus: 3,000 to 4,000 mg a day
No upper limit has been set for the phosphoric acid in cola specifically. Total dietary phosphorus, from all sources rather than phosphoric acid alone, carries regulatory upper limits in the 3000-4000mg/day range, and that figure is not specific to this additive.
Half-lifeNo single figure; hormones and kidneys hold phosphate steady
No single half-life. In the body phosphoric acid becomes phosphate, whose blood level is held in range by hormones, including parathyroid hormone and vitamin D, and by the kidneys, bone and gut. The one measured figure, a serum half-life of 5 to 11 hours, comes from infants with normal kidneys after an acute phosphate overdose, not from drinking cola.
Found inCola soft drinks such as Coca-Cola and Pepsi
Cola-type soft drinks (Coca-Cola, Pepsi and the like) are the primary dietary source of phosphoric acid specifically — delivering roughly 50-100mg phosphorus per 12oz serving via phosphoric acid (Tucker et al., 2006).

Myth check

Phosphoric acid in cola is so corrosive that it will 'dissolve a tooth overnight,' and is single-handedly responsible for soda drinkers' bone loss and osteoporosis.

Head-to-head erosion testing finds colas measurably erosive but among the least erosive of common beverages tested: several fruit juices, sports drinks and other sodas erode tooth enamel faster than cola (Zimmer et al., 2015; Ehlen et al., 2008). Separately, daily cola intake, regular or diet, is associated with modestly lower bone mineral density in observational research (Tucker et al., 2006) — a real but gradual, dose-dependent effect, not an acute corrosive one.

The 'instant dissolving' framing overstates both the speed and the relative severity of phosphoric acid's effects: real erosive and bone-density associations exist, but comparative testing puts colas below many everyday beverages on dental erosion, and the bone-density link is a gradual epidemiological association from habitual daily intake, not a corrosive event.

The findingsStrongest first

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Physical & bodyCola dissolves enamel, and fruit juice did more of it in the same test

Over seven days of soaking, Coca-Cola took 7.5mg off enamel specimens and Coca-Cola Light 5.2mg, below the other eight drinks tested, fruit juices among them.

★★☆Age well

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Physical & bodyWomen who drank cola daily had lower hip bone density; men did not

Against women drinking less than one cola a month, one hip site ran 5.4% lower. The pattern held for diet cola too, and non-cola sodas showed nothing.

★☆☆CautionAge well

Sources4 behind this page

Acidic beverages increase the risk of in vitro tooth erosionEhlen et al., 2008DOI 10.1016/j.nutres.2008.03.001
Colas, but not other carbonated beverages, are associated with low bone mineral density in older women: The Framingham Osteoporosis StudyTucker et al., 2006DOI 10.1093/ajcn/84.4.936
Damage from Carbonated Soft Drinks on Enamel: A Systematic ReviewInchingolo et al., 2023DOI 10.3390/nu15071785
Influence of Various Acidic Beverages on Tooth Erosion. Evaluation by a New MethodZimmer et al., 2015DOI 10.1371/journal.pone.0129462

What we don't know

1 open question

Contested — This is diet recall at a single point in time, so daily cola drinkers may differ from occasional ones in ways nobody recorded, including what they were drinking instead. The difference showed at the hip and not the spine. Daily cola drinkers were not taking in more phosphorus overall, which makes phosphoric acid the authors' inference rather than something they measured.