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What uric acid is, and how it becomes gout

Purines are natural compounds in every living cell, where they build DNA and RNA and help the cell use energy, so they're in your body and in the food you eat. Uric acid is the waste left when your body breaks them down. Your kidneys and gut clear it. When less leaves than arrives, the level in your blood rises, and above about 6.8 mg/dL it can form crystals in a joint. Those crystals are what a gout flare reacts to.

By Oliver Silen Sources checked October 22, 2026

Source: Maiuolo et al. 2016

How uric acid builds up, step by step Read top to bottom. Step 1: purines come from two places, your own cells and food and drink. Step 2: the liver turns them into uric acid, the step allopurinol slows. The uric acid sits in your blood, drawn as a tub with two dashed lines: below 6 mg/dL is the treatment target, and over about 6.8 crystals can form. Step 3: the kidneys clear about two-thirds and the gut about one-third. Between 6 and 6.8 is above target. If blood still stays over 6.8 after that, step 4: crystals settle in a joint, often the big toe. Step 5: the immune system attacks them, which is a flare. Purines come from two places Your own cells break down daily Food and drink meat, seafood, beer purines Liver turns purines into uric acid allopurinol slows this step uric acid over ~6.8: crystals form level here 6 to 6.8: above target below 6 (360 µmol/L): target Uric acid in your blood measured in mg/dL cleared out Kidneys about 2/3, in urine Gut about 1/3 If blood still stays over ~6.8 Crystals in a joint often the big toe Then a flare the immune system attacks the crystals

  1. Purines come in

    From two places: your own cells, which break down and are replaced every day, and food and drink. Eating more meat and seafood raised gout risk in a large study, and beer raises uric acid.

    Source: El Ridi 2017Choi 2004Major 2018

  2. They become uric acid

    Mostly in the liver and gut. Most mammals break uric acid down further, but humans lost the enzyme that does it, so uric acid is where the process stops. Allopurinol, the usual first medicine, slows this step.

    Source: El Ridi 2017Kratzer 2014ACR 2020

  3. The kidneys and gut clear it

    About two-thirds leaves in urine and one-third through the gut. When less goes out than comes in, the level in your blood rises.

    Source: Ichida 2012El Ridi 2017

  4. Too much forms crystals

    Above about 6.8 mg/dL, uric acid can come out of solution as needle-shaped crystals that settle in joints, sooner in cooler ones like the big toe.

    Source: Loeb 1972Dalbeth 2016

  5. Crystals trigger the flare

    The immune system treats the crystals as a threat and sets off the swelling and pain of a gout attack.

    Source: Martinon 2006

Where food fits

Food is one of the two sources, and the one you control. In 47,150 men, eating more meat and seafood raised gout risk and purine-rich vegetables, beans and mushrooms did not, which is why we grade foods by their purine source as well as the amount. Your genes still decide more: across whole populations, diet explains under 1% of the difference in uric acid between people, against about 24% for common genes. Alcohol and sugary drinks push the level the wrong way, and the drinks and alcohol pages carry those numbers.

Source: Choi et al. 2004Major et al. 2018

High uric acid is not gout

About 20% of US adults have high uric acid, and 3.9% have gout, so most people with a high level do not have gout. What your own number means, band by band, is on uric acid levels, explained.

Source: Chen-Xu et al. 2019, NHANES

Bringing the level down

Keeping uric acid below about 6 mg/dL (360 µmol/L) over the long term dissolves the crystals and, in time, makes flares rare. That is why the American College of Rheumatology recommends treating gout to a target below 6, with allopurinol as the preferred first medicine. It works on step 2, by slowing the step that makes uric acid. Flares can still happen while crystals dissolve, and why do I still flare? covers that.

Source: Dalbeth et al. 2016ACR 2020

Quick answers

What are purines?

Natural compounds found in every living cell, where they build DNA and RNA and help the cell use energy. Your body makes them and food carries them, and when they break down, what is left is uric acid.

What is uric acid?

The waste product left when your body breaks down purines, from its own cells and from food. Humans lack the enzyme most mammals use to break it down further, so it stays in the blood until the kidneys (about two-thirds) and gut (about one-third) clear it.

Do purines in food cause gout?

They add to the load. In 47,150 men, eating more meat and seafood raised gout risk while purine-rich vegetables did not. Across whole populations, though, diet explains under 1% of the difference in uric acid between people, against about 24% for common genes.

Why does high uric acid cause gout?

Above about 6.8 mg/dL, uric acid can form needle-shaped crystals in and around joints, and the immune system attacks them, which is the flare. Most people with high uric acid do not have gout: about 20% of US adults have a high level and 3.9% have gout.

Can the crystals go away?

Yes. Keeping uric acid below about 6 mg/dL (360 µmol/L) over the long term dissolves the crystals and, in time, makes flares rare. That is why guidelines treat gout to a target below 6.

Sources

  1. 1. Source: Maiuolo J, Oppedisano F, Gratteri S, Muscoli C, Mollace V. Regulation of uric acid metabolism and excretion. Int J Cardiol. 2016;213:8-14. Purines are the building blocks of DNA and RNA, help run the cell’s energy and signalling, and every cell needs them. In humans their breakdown ends in uric acid.
  2. 2. Source: El Ridi R, Tallima H. Physiological functions and pathogenic potential of uric acid: A review. J Adv Res. 2017;8(5):487-493. Uric acid is made mainly in the liver and intestines, from food purines and from the body’s own dying cells. About two-thirds leaves through the kidneys and one-third through the gut.
  3. 3. Source: Ichida K, et al. Decreased extra-renal urate excretion is a common cause of hyperuricemia. Nat Commun. 2012;3:764. Humans lack uricase, so uric acid is the end product. Two-thirds is excreted by the kidneys and one-third by other routes such as the gut, and a weak gut transporter (ABCG2) raises urate.
  4. 4. Source: Kratzer JT, et al. Evolutionary history and metabolic insights of ancient mammalian uricases. Proc Natl Acad Sci U S A. 2014;111(10):3763-3768. Apes, including humans, cannot break uric acid down, after independent events silenced the uricase gene.
  5. 5. Method: Loeb JN. The influence of temperature on the solubility of monosodium urate. Arthritis Rheum. 1972;15(2):189-192. Urate solubility falls as temperature drops.
  6. 6. Source: Martinon F, et al. Gout-associated uric acid crystals activate the NALP3 inflammasome. Nature. 2006;440(7081):237-241. Urate crystals switch on an immune alarm that releases interleukin-1β, the signal behind a flare.
  7. 7. Source: Dalbeth N, Merriman TR, Stamp LK. Gout. Lancet. 2016;388(10055):2039-2052. Crystals form when urate is high, kidney and gut excretion are central to the level, genes matter, and long-term urate below 360 µmol/L (about 6 mg/dL) dissolves crystals and suppresses flares.
  8. 8. Source: Choi HK, et al. Purine-rich foods, dairy and protein intake, and the risk of gout in men. N Engl J Med. 2004;350(11):1093-1103. In 47,150 men, eating more meat and seafood raised gout risk and purine-rich vegetables did not.
  9. 9. Source: Major TJ, Topless RK, Dalbeth N, Merriman TR. Evaluation of the diet wide contribution to serum urate levels: meta-analysis of population based cohorts. BMJ. 2018;363:k3951. Diet patterns explained under 1% of urate variance, common genetic variants about 24%. Beer was among the foods that raised urate.
  10. 10. Source: Chen-Xu M, et al. Contemporary Prevalence of Gout and Hyperuricemia in the United States: NHANES 2007-2016. Arthritis Rheumatol. 2019;71(6):991-999. Hyperuricemia about 20% of US adults, gout 3.9%.
  11. 11. Source: FitzGerald JD, et al. 2020 American College of Rheumatology Guideline for the Management of Gout. Arthritis Care Res. 2020;72(6):744-760. Treat to a serum urate below 6 mg/dL, with allopurinol, a xanthine oxidase inhibitor that slows uric acid production, as the preferred first medicine.

Values are per 100g unless a note says otherwise, rounded to three significant figures. Per-serving figures are calculated from the unrounded measurement, so recomputing from the rounded number can differ by a milligram or so. A single determination is normal in food composition tables, not a defect. The fructose figure is derived, not a label value: it counts free fructose plus half of sucrose, because sucrose is half fructose and the body treats both the same way. A sucrose-sweetened food therefore carries roughly twice this much total sugar.

Last reviewed October 22, 2026.

Not medical advice. This page explains published research. Talk to your doctor about your own uric acid and whether you need treatment.

See also: uric acid levels · plant vs. animal purines · the food list

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