Greater consumption of plant protein and caffeine is associated with lower serum uric acid levels in kidney transplant recipients (KTRs), a new study finds.
Investigators analyzed the dietary intake of 113 KTRs using two 24-hour dietary recalls. Hyperuricemia was classified as serum uric acid levels exceeding 7.0 mg/dL in men and 6 mg/dL in women. Hyperuricemia in this population is typically attributed to low uric acid excretion due to reduced glomerular filtration rates.
KTRs with elevated uric acid levels ingested lower amounts of carbohydrates, plant protein, total fiber, soluble fiber, caffeine, lactose, calcium, and dairy products.
In adjusted analyses, greater consumption of plant protein predicted variances of uric acid by approximately 2%, Erick P. de Oliveira, PhD, of Universidade Federal de Uberlândia in Minas Gerais, Brazil, and colleagues reported in The Journal of Renal Nutrition. Patients who ingested more caffeine had an approximately 2% reduced likelihood of hyperuricemia.
Cereals (60.1%), fruits (8.2%) and beans (7.4%) were the main foods that contributed to plant protein intake, whereas teas and coffee (48.8%), and chocolates (16.8%) were the main food sources of caffeine intake.
Although consumption of animal protein is commonly associated with hyperuricemia, after an adjusted multiple linear regression analysis only plant protein intake remained associated with uric acid.
Plant proteins contain phenolic acids and flavonoids and low amounts of purine, which may lead to lower uric acid synthesis, Dr de Oliveira’s team suggested. Caffeine and other compounds in teas, coffee, and chocolate may be competitive inhibitors of xanthine oxidase activity, which also decrease uric acid synthesis.
According to the investigators, the data suggest that dietary intake does not seem to be essential for uric acid increases in KTRs, although there may be some effect, even if it is small. They suggested future randomized clinical trials should be performed to determine whether these are important nutritional interventions to promote uric acid reductions in KTRs.
Limirio LS, Santos HO, dos Reis AS, de Oliveira EP. Association between dietary intake and serum uric acid levels in kidney transplant patients. J Ren Nutr. 2021;31:637-647.doi:10.1053/j.jrn.2020.11.009