Transcript: Preventing Gout Attacks with Diet
Over 2,000 years ago, Hippocrates described gout as a “disease of kings,” primarily because it was the wealthy who could afford the rich foods which seemed to precipitate gouty attacks. But now, we can all eat like kings and acquire some diseases of royalty ourselves.
Gout is caused by needle sharp crystals of uric acid in our joints, and uric acid comes from the breakdown of purines. And purines are the breakdown product of genetic material, DNA, the foundation of all life. So, there is no such thing as a purine-free diet, but foods do vary in their purine content, and it was long thought that people with gout just needed to stay away from all high-purine foods, whether from animals, like organ meats, or plants like beans, but this strategy proved ineffective. Yes, all uric acid comes from the breakdown of purines, and so limiting meat makes sense, but that means all kinds of meat, and plant sources have now largely been exonerated.
The association of gout with both alcohol intake and increased dietary purine consumption has been known since ancient times, but there were no prospective trials to back it up… until just a decade ago. The Harvard Health Professional’s Follow-Up Study, about 50,000 men followed for a dozen years, and alcohol intake was strongly associated with an increased risk of gout, and in terms of food, they found an increased risk of gout with higher meat and fish consumption, but not with higher consumption purine-rich plant foods, maybe because the purines in plants are less bioavailable? So, though it’s been suggested that gout sufferers should moderate both purine rich animal and plant foods, their results suggest that this type of dietary restriction may be only applicable to purines of animal origin.
Although it was not surprising that meat and seafood had significant associations with the incidence of gout, this lack of effect of purine-rich plant foods was new. There don’t appear to be any long-term studies showing purine rich, plant foods increase risk, though there are still some guidelines continuing to disseminate outdated recommendations.
Not only has the intake of purine-rich plants not been associated with high uric acid levels, but the vegetables gout sufferers are specifically told to stay away from - mushrooms, peas, beans, lentils, and cauliflower - were actually found to be protective. This may be because foods rich in fiber, folate, and vitamin C appear to protect against uric acid buildup and gout. For example, fiber has been recognized as having a potential role in binding uric acid in the gut for excretion.
Lack of association between purine-rich vegetables and urate could be due to the co-packaging of these beneficial plant components (such as vitamin C, dietary fiber, or some phytochemicals), which may have masked an effect of purine on uric acid. Vegetable intake, regardless of purine content, may also be protective as it may increase uric acid excretion.
By changing the pH of our urine, we can change uric acid clearance. Eating an alkaline diet, a vegetarian diet in this case, was found effective for removing uric acid from the body. Those eating the alkaline diet excreted significantly more uric acid than those eating the acidic diet. As such, uric acid levels in the blood of those eating the acid-forming diet rose within days.
So, one would assume uric acid levels are lower in vegetarians. And indeed, those eating vegetarian long term were found to have significantly lower levels in their blood. To prove cause and effect, though, you need to do an interventional trial, where you take people, change their diets, and see what happens. So, they took ten guys for a study of the build-up of uric acid in the kidneys, kept them on a standard Western diet for five days, and measured their relative super saturation for uric acid. Then, they tried a vegetarian diet for five days and got this. The intake of the vegetarian diet led to a 93% decline in the risk of uric acid crystallization, within days.
Or, you can do it the other way: take a bunch of people with gout, feed them a big meal of meat and see if you can trigger an attack. Seven patients were put in a hospital, stabilized on a low-purine diet, and then challenged with a meat-laden dinner. In response, uric acid levels shot up, and they started getting gout attacks. Then, they added alcohol and uric acid levels shot up even further. In all, just with single meals, they were able to trigger gout attacks in six out of seven patients.
Now, some meat has less purines than others. Superworms have particularly low purine levels, super, because they're like two to three inches long.
Not all animal foods increase gout risk, though. Low-fat dairy products were found to be protective. If that’s the case, we would predict vegans would be at a disadvantage, which is indeed what was found, though these all were within the normal range, which is like 3.5 to 7.
Should gout patients add milk to their diets? Well, although drinking the equivalent of ten cups of skim milk at a time appears to have an acute lowering effect on uric acid levels, in the long term over months, at the equivalent of two cups a day, there was no significant lowering effect. They gave skim milk powder to gout patients for three months, and it did not appear to help. Though soy milk has also been associated with a lower risk of uric acid buildup, there are no interventional trials to back that up.
The bottom line is that we now have good research on how to reduce risk of gout without the use of drug treatments, through modification of diet. That’s important, because allopurinol is the drug of choice. It’s considered generally safe. What does it mean when doctors talk about a relatively safe drug? Well, about 2% of patients develop hypersensitivity reactions, which can sometimes be severe and fatal with a mortality rate of up to 20%--and that’s the safe drug. The other leading drug, colchicine, has no clear-cut distinction between the nontoxic, toxic, and lethal dose.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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