Can Tart Cherry Juice Affect Gout Flares? Inside a 12-Month Trial Protocol

The study “ Effect of tart cherry juice on risk of gout attacks: protocol for a randomised controlled trial” by Kirstie Louise Lamb et al. (2020) sets out a detailed plan to test whether tart cherry juice might influence the risk of gout flares over one year. This protocol outlines the design, methods, outcomes, and analysis plan before any results are known. The authors explain that years of small studies and observational research suggest cherries might lower uric acid and inflammation, but strong clinical evidence is still missing. The randomized controlled trial (RCT) described in this protocol will be carried out in adults with gout who receive Montmorency tart cherry juice or a matched placebo.

The scientific paper explains that gout is a “debilitating and common type of inflammatory arthritis exerting a significant health burden” and affected about 3% of UK adults in 2012. Gout flares happen when monosodium urate crystals build up in joints, especially in the lower limbs, causing intense pain, redness, and swelling. These attacks can last from days to weeks and are strongly linked to long-term high levels of uric acid in the blood ( hyperuricaemia).

The paper notes that gout often occurs alongside other health problems, especially cardiovascular disease (CVD), obesity, and high blood pressure. It also notes that certain foods and beverages, such as seafood, red meat, beer, and sugar-sweetened beverages, are associated with higher uric acid levels and increased risk of gout.

Cherries, especially tart cherries, are rich in polyphenols and anthocyanins, which are bioactive compounds with antioxidant and anti-inflammatory properties. Earlier case reports from the 1950s suggested cherries might help with gout pain and inflammation. More recent small studies have shown that cherry products can acutely lower serum urate, which is uric acid in the blood, and reduce inflammatory markers such as C-reactive protein (CRP).

One observational case cross-over study of 633 people with gout found that cherry consumption was associated with a 35% lower risk of gout flares. However, the authors stress that this was an observational study, so it cannot prove cause and effect and only looked at short-term cherry intake, not regular use over months. Small feasibility trials of cherry products in gout also had important limitations, such as small sample sizes and a lack of proper placebo control.

Despite this limited evidence, many medical societies and charities mention cherries as a possible aid for gout, while regulators such as the U.S. Food and Drug Administration have warned against disease prevention claims about cherry juice. The authors argue that a well-designed randomized controlled trial (RCT) is needed to provide clear, definitive evidence.

This protocol describes a 12-month, double-blind, two-arm, parallel randomized controlled trial in adults aged 18–80 years with a clinical diagnosis of gout and at least one self-reported gout flare in the previous year. Participants will be recruited mainly from primary care practices around Sheffield, UK, using electronic medical records to identify eligible patients. General practitioners will screen for suitability, and written informed consent will be obtained.

Participants will be randomly assigned (in a 1:1 ratio) to:

• Intervention group – daily Montmorency tart cherry 68 Brix concentrate (30 mL concentrate diluted with 220 mL water; total 250 mL/day).
• Placebo group – a low-phenol, cherry-flavoured cordial matched for colour, taste, and tartness, but with far lower phenolic and anthocyanin content.

The tart cherry serving provides about 80 kcal, 20 g carbohydrate, 870 mg phenolics, and 14 mg anthocyanins. The placebo provides about 2.9 kcal, 0.3 g carbohydrate, 13 mg phenolics, and 0.2 mg anthocyanins. The drinks are delivered in identical bottles and labelled only with participant ID to keep both participants and researchers blinded.

Each participant will be followed for 12 months. Study visits occur at baseline, 6 months, and 12 months, and include:

• Anthropometric measures (height, weight, body mass index).
• Fasting blood samples for serum urate, inflammatory markers (CRP, interleukin-6, tumour necrosis factor-alpha), blood lipids, and oxidative stress.
• 24-hour urine collection and spot urine sample to measure urinary uric acid excretion and fractional excretion of uric acid.
• Vascular assessments will use a Vicorder device to measure blood pressure (BP), arterial stiffness, and augmentation index.

Participants will keep diaries to record gout flares, including pain intensity on a 0–10 scale, duration, joint affected, and any treatment. A flare is counted when pain at rest is greater than 3. Diet and physical activity are tracked using 4-day diaries before each lab visit. Compliance is supported with daily calendars, monthly calls, and regular contact when delivering drinks.

Statistical analysis will follow an intention-to-treat approach, including all randomized participants as far as data allow. Generalized mixed model analyses of variance will test differences between groups over time, with significance set at p<0.05. The sample size of 120 allows for about 20% attrition and is powered to detect a marked reduction in flare recurrence from 11% to 2.7% over 12 months.

Because this is a protocol, this scientific paper does not report trial results. Instead, it defines planned primary and secondary outcomes and explains what the researchers expect to find.

The primary outcome is the change in the frequency of self-reported gout attacks from baseline to 12 months, comparing tart cherry juice with the placebo drink. The authors hypothesize that a daily tart cherry concentrate drink over 12 months will reduce the frequency of gout flares relative to placebo.

They state that “the primary objective of this trial is to assess if a daily supplement of tart cherry juice influences the frequency of gout attacks over 12 months relative to a daily supplement of a placebo drink.”

Secondary outcomes are chosen to explore both gout control and broader cardiovascular health:

• Intensity of gout flare pain.
• Serum urate concentration and fractional excretion of uric acid.
• Biomarkers of inflammation (CRP, interleukin-6, tumour necrosis factor-alpha).
• Blood lipids (total cholesterol, LDL, HDL, triacylglycerol).
• Markers of oxidative stress and antioxidant status in lymphocytes.
• Vascular function (brachial and central BP, arterial stiffness).
• Physical activity levels and functional status (pain, daily function, perceived health).

The authors hypothesize that daily tart cherry juice will not only lower flare frequency but also reduce markers of cardiovascular risk, including arterial stiffness, BP, and blood lipids, compared with placebo.

The scientific paper highlights several strengths and limitations:

• Strengths
  • First randomized, double-blind, placebo-controlled trial focused on tart cherry juice for recurrent gout flares.
  • Outcomes are directly relevant to both gout management and its common comorbidities.
  • Includes mechanistic measures (urate handling, inflammation, oxidative stress, vascular health) to understand how tart cherries might work.
• Limitations
  • The 12-month follow-up increases the chance of participant drop-out, which can challenge retention.
  • The placebo cannot be perfectly matched for energy content, which could introduce small differences in calorie and sugar intake between groups.

If the trial later shows that tart cherry juice significantly reduces gout flares, the findings could encourage more research on using tart cherries as an adjuvant dietary option alongside standard gout medications, rather than as a replacement. The protocol is designed to explore both the question of whether there is an effect and how any effect might occur by tracking uric acid, inflammation, oxidative stress, and cardiovascular indicators.

The paper explains that cherries contain polyphenolic compounds with anti-inflammatory effects that may dampen the inflammatory response to urate crystals. It also notes that previous studies have reported that cherry intake can lower CRP and serum urate in both healthy people and those with arthritis. By linking these mechanisms to clinical outcomes, such as flare counts and pain, this trial could help clarify the biological basis for any potential benefits.

Because people with gout often have high cardiovascular risk, the planned measurements of arterial stiffness, blood pressure, and lipids are also important. If tart cherry juice favorably changes these markers, the results could point to one possible dietary approach that supports both joint health and heart health, although any conclusion will depend entirely on the final trial findings.

This scientific paper presents a carefully planned, 12-month randomized controlled trial protocol to test whether Montmorency tart cherry juice can lower the frequency of gout attacks and improve cardiovascular risk markers compared with a cherry-flavoured placebo drink. It builds on earlier observational and small intervention studies, but uses a larger sample, strict blinding, and detailed outcome measures to seek stronger evidence. The main message from this protocol is that the question of tart cherry juice for gout remains open, and this trial is designed to gather clear data that may help answer it. Until the final trial results are published, no firm conclusions about effectiveness can be drawn, but this protocol provides an important framework for future findings.