This page about caffeine and gout was last reviewed, or updated, on 16 May 2011.
Since coffee has been shown to lower uric acid a little, and lower the risk of getting gout, researchers have naturally wondered whether coffee’s best known compound – caffeine – is responsible. Maybe you have too. How could caffeine affect uric acid? As you will read, the truth is currently still elusive, but in the short term, the latest research showed caffeine could give a few gout sufferers a gout attack.
DOES CAFFEINE LOWER OR RAISE URIC ACID?
Caffeine has a diuretic action. It increases the filtration and blood flow in the kidneys, so maybe it increases the kidney’s excretion of uric acid, just like uricosuric (urosuric) drugs such as probenecid, and studies have shown Vitamin C, especially at at 1 gram plus dose. And perhaps caffeine can inhibit uric acid production in humans as do allopurinol and febuxostat. It has shown it can do this in rats.
But does caffeine's diuretic action work to reduce uric acid excretion - perhaps as the body loses water, so uric acid becomes less soluble, and its concentration rises. And is the action of caffeine, despite the above possibly benign gout effects, more likely to increase the risk of gout though an effect of lowering insulin sensitivity?
This means increased insulin resistance and insulin levels. Higher insulin has been shown to inhibit uric acid excretion and thus raise its level in the blood. This makes crystallisation (crystallization) more likely and is the event which is the immediate cause of gout in most cases.
In another study, higher intake of both regular and decaff coffee has been found to be linked to lower C-peptide levels, a marker of the insulin level. If insulin falls, this is good for gout because insulin inhibits uric acid excretion. In this study caffeine did reduce C-peptide slightly (6). But it was coffee, not caffeine, that had the major beneficial effect on C-peptide levels – caffeine wasn’t important for forecasting them.
So caffeine's effect on uric acid and insulin aren't clear.
Which of the two opposing actions of various kinds is dominant is not yet known, but the five coffee studies described on the coffee for gout page, and below, help to unravel the question of caffeine and gout somewhat. The majority have concluded that in the long term, caffeine does not lower uric acid levels. Nor does it raise uric acid.
However, a short term study on the effects of caffeine on the risk of gout (7) found that there were increased risks of a gout attack within 24 hours of consuming caffeinated beverages, compared to those who didn't drink caffeinated beverages.
CAFFEINE AND GOUT RISK
If caffeine helps cause gout, you would expect the studies to show unanimously and clearly that those who drink large amounts of regular, caffeinated, coffee daily have elevated uric acid levels, or higher levels than those who drink less coffee. They don’t, at least in the long term.
If caffeine helps prevent gout you would expect the reverse – higher caffeine intake means lower uric acid levels or a lower risk of gout. But again, with the exception of one study of female nurses, this was not found in four other studies that looked at caffeine and gout, as well as coffee.
So let’s take a peek at what these coffee and gout studies learnt about caffeine and gout. In these studies drinking coffee was linked to lower uric acid levels, or a lower risk of gout, or both, when sufficient cups of coffee daily are drunk. It’s thought that other coffee compounds are responsible for coffee’s beneficial effects on gout and uric acid, not caffeine.Possibly its chlorogenic acid, or other antioxidants in coffee.
The (1) – (5) study references are named on the coffee for gout page where you’ll find more details about these studies such as how much coffee was drunk and how much uric acid fell. Studies (6) and (7) are named at the bottom of this page.
These were the studies.....
COFFEE AND THE RISK OF GOUT IN MEN (1)
In this very large (nearly 46,000 males, average age 54) population study, the researchers could not find a significant link between total caffeine intake, in the coffee, tea, colas and chocolate, which the male study population drank and ate over 12 years, and the risk of gout. Neither could they find a connection in non-coffee drinkers (i.e. from the caffeine in tea and colas), nor in those who got their caffeine from coffee, between caffeine and the risk of gout.
THE U.S. NURSES’ HEALTH STUDY (2)
This study could be “the exception that proves the rule,” as far as caffeine is concerned, although its findings on coffee stood in line with the other studies. This was another large (almost 90,000) population enquiry, this time of female U.S. nurses. In this one, when caffeine from all sources was examined, those who drank most caffeine, compared to those who drank least, had a 48% lower risk of gout. This is the only study where this happened.
THE MIDDLE AGED AND ELDERLY JAPANESE STUDY (3)
This coffee and gout study was published in 2010. It was another large study of 11,662 Japanese men and women aged 49 – 76. Caffeine intake, unlike coffee intake, was not found to be linked to blood uric acid levels.
EXAMINATION OF NHANES III RESULTS (4)
This was another analysis of a large population, in this case of the U.S. Third National Health and Nutrition Examination Survey, 14,758 participants over 20 years old. Again, whilst coffee was shown to lower the risk of hyperuricemia (high uric acid, usually the immediate cause of gout), and the blood uric acid fell as more coffee was drunk, caffeine intake was not related to uric acid levels.
Green tea and gout - no effect from tea (black or green). Tea (black tea) and green tea originate from the same tea plant, Camellia sinensis. The difference between them is essentially the way the leaves are processed. Both teas contain caffeine, although there’s more in coffee. Green tea did not have an effect on the uric acid (UA) level.
Black tea and gout - nor did tea, (black tea). So their caffeine did not affect their UA either. But teas are healthy for gout sufferers in other ways.
JAPANESE ARMED FORCES PRE-RETIREMENT STUDY (5)
Published in 1999, this study found that whilst coffee reduced uric acid levels in 2,240 Japanese armed forces’ personnel who were about to retire, green tea did not change them. Even in those who only drank green tea, and not coffee, there was no serum (blood) uric acid change, up or down. Although green tea does not contain as much caffeine as coffee, it does contain caffeine. So the researchers concluded caffeine did not change uric acid levels in participants.
Any difference between regular and decaffeinated coffee?
Another feature of studies (1), (2) and (4), was that decaffeinated coffee was not found to significantly perform any differently to regular, caffeinated, coffee. Take most of the caffeine out, as in decaffeinated coffee, but uric acid does not rise or fall by a significant amount compared to caffeinated coffee.
A CAFFEINE CONCLUSION, OR IS IT A CONFUSION?
Whether you prefer regular or decaff, it does not seem likely that, in the long term, caffeine makes any difference to your uric acid level, because studies (1) - (5) were long term ones. But in the short term, in the study mentioned above (7) there was an increased risk of a gout attack within 24 hours after consuming caffeinated beverages; a 330% increased risk from six+ servings daily, and a 40% increased risk if you drink three. In this study, the researchers did not find the connection with an increased gout risk from non-caffeinated (decaff) beverages.
But, at present, it's the only study that has found caffeine to carry a risk for gout.
So a realistic and workable conclusion tip might be
If you drink say four to six cups of a caffeinated beverage - coffee, (not tea, colas or energy drinks because coffee gets uric acid down a little and these others don't) - and if within 24 hours, or a few days, you don't have a gout flare, then carry on drinking coffee. In the long term it will lower your uric acid level somewhat. How much?
And if you do have a flare, you've learnt that it's probably the caffeine that's triggered it, as long as you hadn't been consuming a personal gout trigger food or beverage, or a high purine food/beverage, or lived through some other gout trigger event.
More caffeine and gout studies are definitely required.
Caffeine and Gout references
(6) Caffeinated Coffee, Decaffeinated Coffee, and Caffeine in Relation to Plasma C-Peptide Levels, a Marker of Insulin Secretion, in U.S. Women Tianying Wu, Walter Willett, Susan Hankinson, Edward Giovannucci. Diabetes Care Volume 28 No.6, June 2005.
(7) Abstract. Short-Term Effects of Caffeinated Beverage Intake on Risk of Recurrent Gout Attacks Neogi Tuhina, Chen Clara, Chaisson Christine, Hunter David J., Zhang Yuqing. Arthritis Rheum 2010;62 Suppl 10:1362 DOI: 10.1002/art.29128