Hmong Microbiome ANd Gout, Obesity, Vitamin C (HMANGO-C)

Gout, caused by chronic elevation of serum urate (SU), is the most common form of inflammatory arthritis worldwide. About 3.9% of adults in the U.S. suffer from gout and prevalence is even higher in certain ethnicities. Factors that may influence SU include patients' characteristics (gender, weight, renal function, etc.), genetics, and diet. Foods and beverages that have shown positive association with HU and gout are alcohol (particularly beer), purine-rich foods, red meat, seafood, and sugar-sweetened drinks, while inverse association has been found with dairy intake such as skimmed milk and low-calorie yoghurt, coffee and vitamin C. The gut microbiota composition and function have been linked to common chronic human disorders, such as obesity, diabetes, non-alcoholic fatty liver disease, and rheumatoid arthritis. Intestinal microbiota of gout patients were also found highly distinct from healthy individuals in both organismal and functional structures from a small study conducted in China. Strategies to use personal microbiome features to predict glucose response to specific food have been proposed. However, little is known about the impact of microbiota on food and urate-lowering therapy (ULT). The translational significance of a microbiota-guided approach to select appropriate foods and medications that could prevent the elevation of SU for individuals with gout or at high risk for gout is significant. The Hmong are a unique Asian sub-population. Hmong men exhibit a 2-fold higher prevalence of gout, manifesting it earlier in life and experiencing up to 5-fold increased risk of gout-associated complications, compared to non-Hmong in the US. This could lead to higher rates of cardiometabolic diseases (e.g. hypertension, renal disease, type 2 diabetes [T2DM]), which significantly impact morbidity, mortality and healthcare costs. Accordingly, the investigators seek to quantify the impact of vitamin C on patient outcomes, including serum urate level, gout-related symptoms, and obesity (measured by BMI) in both healthy Hmong adults and in Hmong patients with hyperuricemia (HU) and/or gout; identify associations between individuals' taxonomic and functional patterns of gut microbiota and its impact on the serum urate-lowering effect of vitamin C; compare taxonomic and functional patterns of gut microbiota between people with HU and/or gout and people without HU and gout; and identify associations between individuals' taxonomic and functional patterns of gut microbiota and self-reported acute gout trigger foods.

Inclusion criteria

• Self-identified Hmong persons whose both parents are Hmong, with and without hyperuricemia (serum urate (UA) ≥ 6.8 mg/dL ) and/or gout (defined by 2020 American College of Rheumatology Guideline for the Management of Gout) are eligible for the study.
• For those with gout, participants qualify if they have serum UA ≥ 6.8 mg/dL based on the baseline measurement or serum UA < 6.8 mg/dL based on the baseline measurement with at least 1 episode of peripheral joint or bursal swelling, pain, or tenderness (acute gout flare) in their lifetime, (with or without urate-lowering therapy)

Exclusion criteria

• Allergy or sensitivity to vitamin C
• Diagnosis/history of:

• Gastrointestinal surgery including colectomy, ileectomy, and gastrectomy
• Inflammatory bowel disease
• Auto-immune disease
• Type I diabetes mellitus
• Severe kidney disease (i.e., on dialysis)
• End-stage liver disease (i.e. cirrhosis)
• Glucose-6-phosphate dehydrogenase deficiency, (due to increased bleeding risk in those with G6PD deficiency when receiving vitamin C)
• Pregnant or breastfeeding persons
• Current use of:

• Antibiotics
• Probiotics supplement
• Ketogenic diet