Diets high in red meats, saturated fats, and sugars, relative to diets dominated by fruits, vegetables, and legumes, are associated with an increased risk of gout independent of an underlying genetic risk, according to independent sets of data presented at the annual European Congress of Rheumatology.
Only one of the two retrospective analyses evaluated diet in the context of a genetic risk score, but “no evidence of an additional or multiplicative interaction” was seen when genetic risk was evaluated on top of the risk already known to be associated with a Western diet, reported Chio Yokose, MD, a researcher and clinician in the division of rheumatology, allergy, and immunology at Massachusetts General Hospital, Boston.
A parallel study presented at the EULAR Congress looked at the impact of a proinflammatory diet. Although genetic predisposition was not considered in this analysis, this diet, too, was associated with increased risk of gout independent of a long list of other variables. Each of the studies supports the potential for diet to be a target for risk reduction.
“Adhering to a diet with low inflammatory potential may mediate systemic and metabolic inflammation,” reported Natalie McCormick, PhD, a research fellow at Massachusetts General Hospital. She said the association of an inflammatory diet with gout is analogous to previous studies linking this type of diet to type 2 diabetes mellitus and cardiovascular disease because the inflammatory response is a pathogenic factor.
The two retrospective studies evaluated different but overlapping sets of data. Yokose and McCormick collaborated on both studies.
In the study of Western diet, which was restricted to women, the focus was on both diet and genes. Using food frequency questionnaires completed by 18,512 women participating in the Nurses’ Health Study (NHS), subjects were placed in quintiles for relative exposure to Western diets and for an interventional diet called DASH (Dietary Approaches to Stop Hypertension) that is high in fruits and vegetables.
A genetic risk score (GRS) was developed for participants using 114 serum urate single-nucleotide polymorphisms from a genomewide association study.
For the Western diet, there was a stepwise increased risk of gout per quintile associated with greater exposure. For the DASH diet, the same phenomenon was seen in reverse so that risk of gout was incrementally lower per quintile defining greater adherence.
When considered as a variable, GRS altered these basic relationships only for the DASH diet. After adjusting for multiple factors, such as age, menopause, use of hormone therapy, and hypertension, there was no significant interaction observed for genetic predisposition in relation to the Western diet.
For the DASH diet, there was an even greater reduction in the relative risk of gout among those with a high GRS if they were in the quintile defining greatest adherence to the DASH diet. Although this association fell just short of reaching statistical significance (P = .056), Yokose indicated that it was a strong trend.
Gout Similarly Associated With Proinflammatory Diet
The proinflammatory diet shares many food items with the Western diet, including refined carbohydrates, sweetened beverages, red meat, and fried foods. The study that evaluated its impact used dietary history collected from in 164,090 women in the NHS and 40,598 men in the Health Professionals Follow-up Study. In both, participants completed dietary questionnaires every 4 years. Patients were assigned an Empirical Dietary Index of Inflammatory Potential (EDIP) score on the basis of these questionnaires.
When the 2874 incident gout cases were evaluated by EDIP quintile, those in the highest had a 50% greater risk of gout than did those in the lowest when adjusted for multiple potential confounders. When stratified by intake of alcohol, the impact of being in the highest quintile of inflammatory diet was even greater, producing a 2.37-fold increased risk of gout.
Impact of Weight on Risk for Gout
The impact of proinflammatory diet was detectable even after adjusting for adiposity, a gout risk factor reconfirmed in a third study presented at EULAR by this same team of investigators. In that study, presented by Yokose, a GRS above the mean was associated with a further increased likelihood of gout among those with elevated body mass index. However, obesity remained a risk factor for gout even among those with a low GRS.
The data from this study indicate “maintaining healthy weight is an important gout prevention strategy, regardless of underlying genetic risk,” Yokose reported.
All three studies reinforce diet as a modifiable risk factor for gout. According to both Yokose and McCormick, healthy diets should be considered as a gout prevention strategy.
Annelies Boonen, MD, PhD, professor of internal medicine (rheumatology) at the University of Maastricht (the Netherlands), did not challenge these conclusions. However, she cautioned that it is “very difficult to evaluate food questionnaires.” She further noted that retrospective analyses complicate efforts to control for the many potential confounders.
Ultimately, healthy diets can be recommended for many reasons, particularly in individuals with other risk factors for gout. For this reason, Boonen indicated that it will be difficult to prove definitively that gout can be prevented by avoiding Western diets and other diets high in proinflammatory foods. However, definitive proof of this benefit might not be essential for the purpose of a general recommendation to eat healthy foods.
Yokose and McCormick reported no potential conflicts of interest.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.