Effect of nibbling versus gorging on cardiovascular risk factors: Serum uric acid and blood lipids

Nibbling has been reported to decrease serum cholesterol under fasting conditions, as well as the incidence of cardiovascular disease. It has been suggested that these effects are partly attributable to reduced concentrations of serum insulin, which are also observed. However, data on the effects of nibbling on serum lipids throughout the day are not available, nor is it known how nibbling affects serum uric acid as a further insulin-related risk factor for cardiovascular disease. We have attempted to address these issues. Seven healthy men consumed identical diets in a randomized crossover design either as three meals daily (control) or as 17 meals daily (nibbling) for 2 weeks. On day 13, serum lipid levels were measured over the course of the day (12 hours) together with the 24-hour urinary excretion of mevalonic acid as an indicator of hepatic cholesterol synthesis. Concentrations of uric acid in serum and 24-hour urinary excretion of uric acid were also determined. Mean (±SE) percent treatment differences in day-long total, low-density lipoprotein (LDL), and non-high-density lipoprotein (HDL) cholesterol, and apolipoprotein (apo) B were significant, with lower values on the nibbling diet as compared with the control diet (8.1% ± 1.6%, P = .002; 12.2% ± 2.6%, P = .005; 10.1% ± 1.6%, P < .001; and 9.9% ± 2.6%, P = .008, respectively). No significant difference was seen in the total to HDL cholesterol ratio or in urinary mevalonic acid excretion. However, the percent difference between treatments in total cholesterol levels was directly related to the percent difference in urinary mevalonic acid excretion (r = .94, P = .005, n = 6). The mean fasting concentration of uric acid was significantly lower during the nibbling period as compared with the three-meal period (5.8% ± 1.8%, P = .019). Urinary uric acid excretion was also increased on nibbling (26.3% ± 7.9%, P = .021), and the treatment difference related to the reduction in serum insulin over the day (r = -.83, P = .041). We conclude that spreading the nutrient load over time reduces serum risk factors for cardiovascular disease. Our results suggest that these effects may be partly due to lower serum insulin concentrations. Lower insulin concentrations may lead to increased urinary uric acid excretion and possibly reduced hepatic cholesterol synthesis, since the treatment difference in urinary mevalonic acid excretion, although nonsignificant, related significantly to the treatment difference in serum cholesterol.