Tuesday, March 22, 2016

Diet, Uric Acid and Gout

The conventional advice surrounding diet and gout will recommend that to reduce the consumption of high protein and high purine foods.  On the other hand, people giving advice in alternative health communities may argue against the need reduce protein and purine consumption and then stress the importance of the ‘fructose > uric acid’ mechanism

In a couple of earlier blog posts I looked evidence from clinical trials on how protein and fructose affect uric acid

  • Fructose increases postprandial uric acid, but will only increase fasting uric acid if it increases insulin resistance
  • High protein and purine meals will likely increase postprandial uric acid, but have a modest or no effect on fasting uric acid 

If you deal with the underlying causes (such as insulin resistance (see initial post)) then you no longer have to worry about the triggers (protein, purines, fructose, etc).  This will often deal with other current or future health issues rather than just putting a bandaid on the current problem.  This is particularly important for gout where foods rich in protein, purines or fructose include meat, fish, organ meats, legumes, some vegetables, fruit and chocolate*.  This list includes most whole foods and many of the healthiest things to eat.  Many high purine foods would have been staples in the diet of ancient humans prior to agriculture (grains and dairy) and purines could potentially be a measure of cellularity as as RNA is a major source of purines

But the postprandial effects shouldn’t be discounted** as they could potentially trigger a gout attack in a susceptible person.  Much of the rest of the literature on how diet affects postprandial uric acid is concerned with the postprandial inflammatory response.  (I wrote about this an earlier post on how consumption of most macronutrients leads to postprandial inflammation but several substances in whole foods and exercise have been found to protect against this).  However, the outcomes of these studies are mixed and there are two contradictory narratives.

In healthy overweight middle-aged adults, a high calorie (1416 kcal), moderate protein (51g, 14%) high fat (82g, 52%) and low purine meal increased postprandial triglycerides, inflammation and uric acid levels, whereas other plasma antioxidants (uric acid is an antioxidant) were not affected [1].  A later study using the same meal found this postprandial increase in uric acid to be prevented by antioxidant and polyphenol rich fruit juices [2].  The increase in uric acid is thought to be due to an endogenous antioxidant response to postprandial oxidative stress that can be prevented by ingestion of antioxidant-rich and polyphenol rich fruit juices [1] [2]

Whereas other studies have found that dietary fat has the opposite effect in slightly or non-significantly lowering uric acid.  One study found that 60g of fat (12g SFA, 35.35g MUFA, 12.75g PUFA) slightly but significantly decreased uric acid by from 288 to 278 umol/L and that this correlated with oxidative stress [3].  Another study found heated or unheated olive oil or safflower oil non-significantly reduced uric acid [4].  The explanation here is that postprandial oxidative stress from the increase in postprandial triglycerides lowers endogenous antioxidants such as uric acid, and that a set point for plasma uric acid increases in response to postprandial oxidative stress [3]

Regardless of whether postprandial inflammation increases or decreases uric acid it’s probably a good idea to reduce it (via fruits and vegetables, other whole foods, exercise, etc) as this inflammation alone may contribute to triggering a gout attack

* Dairy and coffee are rich in protein and purines respectively but both are strongly inversely associated with the incidence of gout in observational studies, while fruit and purine rich vegetables aren’t significantly associated with the incidence of gout.  This might be due to other components of these foods lowering uric acid [5]

** “Since the acute effects of fructose to raise blood pressure occur during the ingestion of fructose (and are likely mediated by uric acid), it is not surprising that the authors did not show an effect on blood pressure; indeed, a similarly designed study would conclude that glucose-rich diets do not increase insulin levels.” [6]

That’s probably it for gout.  I’ll leave you with few other resources:

  • A draft chapter on gout not included in Good Calories, Bad Calories (thanks Zooko for the link)
  • An open access Cochrane meta-analysis on dietary supplements for gout [7]
  • Examine.com’s page on for uric acid [8]

3 comments:

  1. nice post steven.

    Gout is one of the hardest nutrition topics i've tried to explain to a 28 year old friend of mine who has gout: 'meat, fish, organ meats, vegetables etc. don't cause gout, but can trigger it, so you should initially limit some of the non-essential ones until you improve your IR...and then go back to eating them in a LCHF fashion.'

    As you can guess, my message was not received positively. Will keep this post as a reference though, thanks!

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    1. Thanks Raphi

      Wow, gout at 28! Yes, there's not a great understanding in the general public on triggers vs. underlying causes

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