Higher Uric Acid Levels in Vegans
I’m going to take a brief break from the antioxidant discussion to report on a cross-sectional study just released from EPIC that shows vegans to have higher levels of uric acid than lacto-ovo and pesco-vegetarians (people who eat no meat other than fish).
To quote the authors, “Uric acid is the end product of purine metabolism, generated from the breakdown of DNA, RNA and ATP… High circulating concentrations of uric acid can lead to gout, a common form of arthritis, and have also been linked to chronic kidney disease, cardiovascular disease and cancer.”
In the model adjusted for age and alcohol intake (but not body mass index), the results were (µmol/l):
Men
Meat-eaters – 323
Pesco – 307
Lacto-ovo – 301
Vegan – 336
Women
Meat-eaters – 239
Pesco – 224
Lacto-ovo – 228
Vegan – 243
In our correspondence, author Paul Appleby told me that the differences between the vegans and the pesco/lacto-ovo groups were statistically significant for both genders, and the differences between the vegans and meat-eaters were statistically significant for men only.
How could this be?! Apparently, dairy products have been shown to lower uric acid levels. And in this study, there was a significant positive correlation between uric acid and soy protein intake in men.
The good news is that these levels are still within the normal range which is 202-416 µmol/l for men and 143-357 µmol/l for women (2). And even though the differences were statistically significant, they were not huge (about 11% in men and 8.5% in women).
These levels do not appear to be associated with an increased risk of kidney disease (3) or cardiovascular disease (4). One study found an increase in risk of stroke for uric acid levels above 297 µmol/l, but another did not find a statistically significant difference for levels above 410 µmol/l (4).
Uric acid is an antioxidant and has been studied for its potential to prevent cancer, but the findings have not been in that direction. One study found an increased risk for cancer above the normal levels (5), while another found an association of cancer in men (women were not in the study) in the range of the vegans in the EPIC study (6). The authors (6) noted that vitamin B12 deficiency can increase uric acid levels and also stated, “we hypothesize that elevated [serum uric acid] acts as a valuable, long-term, surrogate parameter, indicative for a life-style which is at increased risk for the development of cancer, but does not function as an independent risk factor or even carcinogenic substance by itself.”
Given all the above, I do not think there is much to worry about, though it would be interesting to see if cancer deaths are related to uric acid levels among vegans in EPIC (if there are enough participants to determine this).
February 18th, 2013 at 2:23 pm
It’s interesting to see so much research being done that differentiates between vegans and lacto-ovo vegetarians! It seems like with a lot of your older blog posts, you had to speculate about how things applied to vegans because either there were no vegans in the studies or the authors did not differentiate between different types of vegetarians.
Anyway, I was actually wondering about uric acid recently because of observations of my own urine that I won’t discuss in detail. I didn’t know it could possibly be associated with B12 deficiency. I have actually been eating less fortified food than I was the last time I got my nutrient levels tested.
February 18th, 2013 at 3:34 pm
“And in this study, there was a significant positive correlation between uric acid and soy protein intake in men.”
Is there any way to know if the soy they consumed in this study was isolated or not? Also how much soy was consumed.
February 18th, 2013 at 3:50 pm
>The authors (6) noted that vitamin B12 deficiency can increase uric acid levels and also stated, “we hypothesize that elevated [serum uric acid] acts as a valuable, long-term, surrogate parameter, indicative for a life-style which is at increased risk for the development of cancer, but does not function as an independent risk factor or even carcinogenic substance by itself.”
If vegans had been lower, you can bet your bottom dollar certain groups would be screaming that vegans have less cancer! (Not just lower risk of cancer, they’d actually say “less cancer!”)
February 18th, 2013 at 4:01 pm
Josh,
I calculate that the vegans averaged 12.7 g of soy protein per day for women (3.0% of energy, energy was 7076 kj/d (1691 kcal)) and 12.4 g per day for men (2.6% of 8001 kg/d (1912 kcal)).
February 18th, 2013 at 4:01 pm
Josh,
I forgot – no the study didn’t distinguish between isolated soy protein and other soy protein.
February 18th, 2013 at 9:52 pm
Hi Jack,
Did the EPIC study have the data to check for a negative correlation between B12 status and uric acid levels? What if it’s mostly down to more plant protein (low B12, unless fortified) and less B12 = higher uric acid?
February 18th, 2013 at 10:10 pm
mine is 315 after 4.5 years of veganism .
i do consume soy but i can’t say that alot .
some tofu occasionally and regular consumption of soy milk
February 18th, 2013 at 10:14 pm
Syd,
The EPIC authors didn’t mention the correlation between B12 deficiency and uric acid and they did not report measuring it in that study. You might ask Paul Appleby on IVU-Sci.
February 19th, 2013 at 5:40 am
Hi Jack,
is there a danger in consuming too much soyprotein? I’m an endurance athlete and I’ve got a protein intake of 120-130g per day, about 50-60g are from soy (Soyproteinisolate, Tofu, Soymilk).
Many thanks for your answer and your blog.
February 19th, 2013 at 8:28 am
But I know that uric acid is an antioxidant, is correct?
February 19th, 2013 at 8:50 am
Andrea,
Yes – the authors of one of the cancer studies said that they were investigating uric acid levels and cancer to see if it could prevent cancer, but they found uric acid to be correlated with cancer instead.
February 19th, 2013 at 8:58 am
Stefan,
That’s about 5-7.5 servings. Soy intakes that high have not been studied much, but up to 3 servings a day have not been shown to be harmful to anyone except people with subclinical hypothyroidism (in which case less than one serving was shown to be harmful).
Here is an article I wrote examining the dangers of soy: http://veganhealth.org/articles/soy_wth I haven’t updated it since 2011, but I’m not aware of any new research that would change the conclusions.
February 21st, 2013 at 9:19 pm
I’ve had gout while on a long-term (30+ yrs.) vegan diet. My uric acid level was and is high normal; curiously, one can have gout while within the normal range. Luckily, mine was in a joint where it could be treated surgically; that isn’t usually the case. Now I only have pain in that toe if I get dehydrated. I’ve never found that plant purines were a problem. I eat soy, but rarely consume isolated soy protein.
February 27th, 2013 at 2:35 pm
About 15 years ago I read an article warning that nutritional yeast will raise uric acid levels (it’s ridiculously high in protien). I was consuming moderate amounts daily so I went and had my uric acid level taken. Sure enough, it came back high. I stopped using it for 6 weeks (this was torture because I love it on popcorn), and had my u.a. level re-checked and it came back well within normal. I still use nutritional yeast, but very sparingly and my u.a. levels remain in the high normal range. I now usually warn new vegans to take it easy on the nutritional yeast. It’s easy to go overboard if you’re suffering cheese withdrawal!
February 28th, 2013 at 5:56 am
Stefan -
If your soy protein isolate is in the form of protein powder, you can try other plant-based protein powders that contain protein from pea, brown rice, hemp, etc.
March 28th, 2013 at 9:37 am
Were the vegans consuming more fruit? Uric acid is a by-product of fructose metabolism.