The role of diet in gout has long been controversial. Highly purine-restricted diets have been shown to reduce serum urate modestly, but have been found to be very unpalatable to patients. It has been unclear whether all dietary proteins are equally likely, via the purines from their breakdown, to raise serum urate and increase the risk of gout.
It is not as yet proven that urate acts directly as a coronary risk factor in humans, although animal studies have been suggestive. However, gout is clearly associated with a number of known coronary risk factors, including obesity, hypercholesterolemia, the metabolic syndrome, hypertension and insulin resistance. The ideal diet for gout would be beneficial both for lowering serum urate and opposing hyperlipidemia.
As Fam has noted, "a rigid purine-restricted diet is of dubious therapeutic value and rarely can be sustained for long." Extension of our knowledge of the relative risk of different types of dietary protein would be very helpful in designing a diet for gout which might be better tolerated by patients.
Choi et al looked at the intake of purine rich foods, dairy and protein, on the risk of gout in men. They noted that previous data had shown that a dairy-free diet increased serum uric acid, but the effect of dairy intake on clinical gout development had not been studied. They studied 47,150 men (in the Health Professionals Follow-Up Study) and assessed their diet every four years. Study participants who reported a history of gout were excluded from analysis. During their 12-year study, 730 new cases of gout occurred.
They found that the men who ate the most meat and seafood had the highest risk of developing gout (RR 1.41 and 1.51 respectively), and that those with the highest intake of dairy products, especially low-fat dairy products, had the lowest risk (RR 0.42). The intake of total protein and of purine-rich vegetables did not appear to change the risk of gout. These results were independent of classical gout risk factors, such as high body-mass index, use of alcohol, diuretic use and chronic renal failure.
Their proposed explanation for the beneficial effect of dairy protein related to the uricosuric effect of this type of protein, in addition to the low purine content of dairy protein. They also pointed out that inadequate data presently exists as to the bioavailability of purines in various foods.
In the past, gout patients were generally advised of the potential risks of high intake of meat or seafood. However, they also had been advised of the relatively high purine content of certain vegetables, such as asparagus, beans and spinach. While dairy intake was generally considered not to be a negative factor, patients were generally not advised that increased low-fat dairy intake might be protective against gout.
The greatest strength of this study is its size and its prospective nature. A limitation is that it studied only men who had not had prior gout, so that the effects of the dietary elements in patients already suffering with gout could be different. Another limitation is that the gout cases were not crystal-documented, but depended rather on the "softer" definition of meeting 6 of 11 American College of Rheumatology criteria.
The authors of the study on dietary protein intake caution that "hurdles exist" before applying this data to clinical practice. However, since following the classical diet for gout, with restriction of meat, seafood and high-purine vegetables is problematic, it is reasonable to make use of some of this study's findings until more data is available. For example, it may be reasonable to focus patients on meat and seafood reduction, while backing off on any vegetable restriction and encouraging an increase in low-fat dairy intake.
Another article from the same group has looked at alcohol intake and the risk of developing gout in middle-aged men. Since alcohol increases hepatic production of uric acid and decreases the excretion of uric acid from the kidney, it has been assumed that any type of alcohol would be a gout risk. The data in this article is far from definitive in answering this question, but in view of its large sample size deserves consideration. The study found that beer intake was the highest risk for the development of gout, followed by hard liquor. Moderate intake of wine, two glasses of wine a day or less, was not associated with the development of gout. It should be emphasized that this study was not looking at the effect of alcohol intake (of any kind) on patients who already had gout. We therefore need to be cautious in extrapolation. It would not be unreasonable to advise patients that beer seems even worse than wine for causing an initial episode of gout, but it seems prudent to continue to advise the patient with already-established gout to minimize alcohol consumption of any kind.
 Fam AG. Gout, diet, and the insulin resistance syndrome. J Rheumatol. 2002 Jul;29(7):1350-5.
Choi HK, Atkinson A, Karlson EW, Willett W, Curhan G: Purine-rich foods, dairy and protein intake, and the risk of gout in men. N Engl J Med. 2004 Mar 11;350(11):1093-103.
 Choi HK, Atkinson K, Karlson EW, Willett W, Curhan G. Alcohol intake and risk of incident gout in men: a prospective study. Lancet. 2004 Apr 17;363(9417):1277-81.