Purines and Gout: Managing Uric Acid on a Low-Carb Diet
Understanding the relationship between diet, purines, and gout risk
Key Takeaways
- Purines are natural compounds found in many foods that break down into uric acid [1]
- High uric acid can trigger gout - painful joint inflammation caused by monosodium urate crystal deposition [2]
- Acute purine intake increases gout attack risk by almost 5-fold in people with gout [3]
- Low-carb diets may temporarily raise uric acid during adaptation, but long-term effects may be beneficial [4]
- Dairy consumption is associated with lower gout risk (OR 0.56) [5]
What Are Purines?
Purines are natural compounds found in the cells of all living things. Uric acid is the metabolic end product of purine metabolism in humans [1:1]. When your body breaks down purines (either from food or from your own cells), it produces uric acid as a byproduct.
Most people excrete uric acid through their kidneys without any issues. However, when uric acid levels get too high (hyperuricemia), it can crystallize in joints as monosodium urate (MSU) crystals, causing the intense pain known as gout [2:1].
The Uric Acid Pathway
The final step of purine metabolism is the conversion of hypoxanthine to xanthine, followed by conversion to uric acid by xanthine oxidase [1:2]. Unlike most mammals, humans lack the enzyme uricase that would further break down uric acid, making us susceptible to hyperuricemia.
- You eat foods containing purines
- Your body also produces purines during cell turnover
- Purines are broken down into uric acid by xanthine oxidase
- Kidneys filter uric acid into urine
- If levels exceed excretion capacity, crystals can form
Purine Levels in Common Foods
A 12-year prospective study of 47,150 men documented 730 confirmed cases of gout and established the relationship between dietary purines and gout risk [6].
Very High Purine Foods (Limit or Avoid)
| Food | Purines (mg/100g) | Gout Risk |
|---|---|---|
| Organ meats (liver, kidney) | 300-600 | High |
| Anchovies | 410 | High |
| Sardines | 345 | High |
| Mussels | 310 | High |
| Herring | 200 | High |
| Game meats | 200-300 | High |
Moderate Purine Foods (Eat in Moderation)
| Food | Purines (mg/100g) | Gout Risk |
|---|---|---|
| Beef | 110-130 | Moderate |
| Pork | 100-145 | Moderate |
| Chicken | 100-125 | Moderate |
| Salmon | 100-170 | Moderate |
| Spinach | 57 | Low* |
| Asparagus | 23 | Low* |
*Plant purines show no association with gout risk [5:1]
Low Purine Foods (Generally Safe)
| Food | Purines (mg/100g) |
|---|---|
| Eggs | 2-5 |
| Cheese | 0-10 |
| Milk | 0-5 |
| Most vegetables | 10-50 |
| Nuts | 10-30 |
| Butter/oils | 0 |
Meta-Analysis: Dietary Factors and Gout Risk
A comprehensive meta-analysis examined the relationship between various dietary factors and gout/hyperuricemia risk [5:2]:
| Dietary Factor | Odds Ratio | Effect |
|---|---|---|
| Red meat | 1.29 | Increases risk |
| Seafood | 1.31 | Increases risk |
| Alcohol | 2.58 | Strongly increases risk |
| Fructose | 2.14 | Strongly increases risk |
| Dairy products | 0.56 | Decreases risk |
| Soy foods | 0.85 | Decreases risk |
| High-purine vegetables | 0.86 | No increased risk |
Notably, high-purine vegetables were not associated with increased gout risk, and may even be protective.
Low-Carb Diets and Uric Acid
The Adaptation Phase
When you first start a low-carb or keto diet, you may experience a temporary increase in uric acid levels. This happens because ketones compete with uric acid for excretion in the kidneys, and rapid weight loss releases purines from broken-down cells.
This adaptation phase typically lasts 2-6 weeks.
The BHB-Inflammasome Connection
Research from Yale University demonstrated that the ketone body β-hydroxybutyrate (BHB) specifically inhibits the NLRP3 inflammasome, which is the key driver of gout inflammation [4:1]. In animal studies, a ketogenic diet:
- Increased β-hydroxybutyrate levels
- Protected against joint swelling and tissue damage
- Reduced systemic inflammation normally seen during gout
The researchers concluded that BHB may serve as an anti-inflammatory treatment for gout, achievable through dietary modification.
Long-Term Benefits
After the initial adaptation, most people may see improvements because:
- Lower insulin levels improve kidney function and uric acid excretion
- Reduced fructose intake (a major driver of high uric acid) [5:3]
- Weight loss reduces overall uric acid production
- BHB has anti-inflammatory effects on gout pathways [4:2]
Preventing Gout on Low-Carb
Hydration is Critical
Uric acid crystals form more easily when you're dehydrated. On a low-carb diet, you naturally lose more water, making hydration even more important.
Daily water targets:
- Minimum: 2-3 liters (8-12 cups)
- More if you're active or in hot weather
- Add electrolytes to support absorption
Manage the Transition
If you have a history of gout, consider a gradual transition to low-carb:
- Reduce carbs slowly over 2-4 weeks instead of going cold turkey
- Stay extremely well-hydrated during the first month
- Limit very high purine foods initially
- Consider cherry extract - systematic reviews show it may reduce gout flares [7]
Keto-Friendly, Lower-Purine Protein Sources
- Eggs (excellent, very low purine)
- Cheese and dairy (associated with lower gout risk) [5:4]
- Chicken and turkey (moderate purine, but lower than red meat)
- Fish (choose lower purine options like cod, tilapia)
- Plant proteins (tofu, tempeh - not associated with gout risk)
Foods That Help Lower Uric Acid
Cherries and Berries
A systematic review of six studies found that gout patients regularly consuming cherry extract or juice reported fewer gout flare-ups [7:1]. A positive correlation was observed between cherry intake and decreased serum uric acid concentration.
Vitamin C
A randomized controlled trial found that supplementation with 500 mg/day of vitamin C for 2 months reduced serum uric acid by 0.5 mg/dL [8]. A meta-analysis of 16 RCTs confirmed that vitamin C supplementation significantly lowers serum uric acid [9].
Low-carb sources of vitamin C include:
- Bell peppers
- Broccoli
- Cauliflower
- Leafy greens
Low-Fat Dairy
The NHANES III study and prospective cohort data consistently show that dairy consumption is associated with lower serum uric acid levels and reduced gout risk [10] [5:5]. The proteins in dairy may help with uric acid excretion.
Common Questions
Does eating protein cause gout?
Not directly. Protein itself doesn't cause gout - it's the purines in certain protein sources. The Health Professionals Follow-up Study found that total protein intake was not associated with gout risk [6:1]. You can eat plenty of protein on keto while choosing lower-purine options.
Should I avoid all organ meats?
If you have gout or are at high risk, limiting organ meats is wise. They contain 300-600 mg purines per 100g, which is substantially higher than muscle meats [6:2].
Can I eat seafood on keto if I have gout?
Yes, but choose wisely. The meta-analysis showed seafood increases gout risk by 31% (OR 1.31) [5:6]. Shellfish and oily fish like sardines and anchovies are very high in purines. White fish and salmon are moderate and generally better tolerated.
Will keto make my gout worse?
It might temporarily during the first few weeks of adaptation due to ketone-uric acid competition for renal excretion. However, research suggests the ketone body BHB has anti-inflammatory effects that may help gout long-term [4:3].
Warning Signs of a Gout Attack
Seek medical attention if you experience:
- Sudden, intense joint pain (often the big toe)
- Swelling and redness around a joint
- Heat in the affected area
- Limited range of motion
Gout attacks often come on suddenly, frequently at night. Early treatment can reduce the duration and severity of an attack.
The Bottom Line
Managing purines on a low-carb diet is absolutely possible:
- Stay well-hydrated - this is the most important factor
- Choose lower-purine proteins like eggs, dairy, and poultry
- Limit organ meats and certain seafood if you're at risk
- Be patient during adaptation - temporary uric acid increases are normal
- Consider supplements like vitamin C (shown to reduce uric acid by 0.5 mg/dL) [8:1] and cherry extract [7:2]
- Consume dairy - associated with 44% lower gout risk [5:7]
The long-term anti-inflammatory effects of ketones (BHB) on the NLRP3 inflammasome may actually make a ketogenic diet beneficial for gout management [4:4].
References
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Dalbeth N, Merriman TR, Stamp LK. Gout. Lancet. 2016;388(10055):2039-2052. PubMed ↩︎ ↩︎
Zhang Y, Chen C, Choi H, et al. Purine-rich foods intake and recurrent gout attacks. Ann Rheum Dis. 2012;71(9):1448-1453. PubMed ↩︎
Goldberg EL, et al. β-Hydroxybutyrate Deactivates Neutrophil NLRP3 Inflammasome to Relieve Gout Flares. Cell Rep. 2017;18(9):2077-2087. PubMed ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Li R, Yu K, Li C. Dietary factors and risk of gout and hyperuricemia: a meta-analysis and systematic review. Asia Pac J Clin Nutr. 2018;27(6):1344-1356. PubMed ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎
Choi HK, Atkinson K, 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;350(11):1093-1103. PubMed ↩︎ ↩︎ ↩︎
Schumacher HR Jr, Chen LX. Effectiveness of Cherries in Reducing Uric Acid and Gout: A Systematic Review. J Evid Based Integr Med. 2019;24:2515690X19878066. PubMed ↩︎ ↩︎ ↩︎
Huang HY, Appel LJ, Choi MJ, et al. The effects of vitamin C supplementation on serum concentrations of uric acid. Arthritis Rheum. 2005;52(6):1843-1847. PubMed ↩︎ ↩︎
Juraschek SP, Miller ER 3rd, Gelber AC. Effect of oral vitamin C supplementation on serum uric acid: a meta-analysis of randomized controlled trials. Arthritis Care Res. 2011;63(9):1295-1306. PubMed ↩︎
Choi HK, Liu S, Curhan G. Intake of purine-rich foods, protein, and dairy products and relationship to serum levels of uric acid. Arthritis Rheum. 2005;52(1):283-289. PubMed ↩︎