Low-calcium diet prevents fructose-induced hyperinsulinemia and ameliorates the response to glucose load in rats

Abstract

BackgroundConsuming a fructose-rich diet leads to hyperinsulinemia, impaired glucose tolerance, and insulin resistance. In humans, the consumption of high levels of refined sugars often coincides with a diet containing suboptimal levels of calcium. Calcium and carbohydrate metabolism interact, so there is potential for fructose to have different health outcomes depending on whether the diet is calcium-rich or calcium-poor.MethodsWe evaluated the metabolic effects of feeding fructose to rats that were maintained on either a calcium-replete diet or a low-calcium diet. Growing male Sprague Dawley rats were fed diets based on the AIN-93G formulation, with the main source of carbohydrate derived either from a mixture of cornstarch and sucrose or from fructose. Half the rats given each carbohydrate source were fed calcium at recommended levels (125 mmol/kg Ca2+); the others were fed a diet low in calcium (25 mmol/kg Ca2+). At various times, glucose and insulin tolerance tests were conducted to assess glucose metabolism.ResultsRats fed low-calcium diet had lower fasting insulin levels irrespective of the carbohydrate source they ate. They had a normal glycemic response to a glucose load and did not develop hyperinsulinemia under conditions of fructose feeding. The drop in blood glucose levels in response to insulin injection was larger in rats fed low-calcium diet than in those fed calcium-replete diet.ConclusionsLow-calcium diet prevented fructose-induced hyperinsulinemia and improved glucose handling under conditions of fructose feeding. Potential mechanisms underlying these effects of the low-calcium diet remain to be determined, but possibilities include impairment of insulin release from the pancreas and improved peripheral insulin sensitivity.

Pre-diagnostic carbohydrate intake and treatment failure after radical prostatectomy for early-stage prostate cancer

“…Lower levels of circulating IGF-1 is known to be associated with reduced PCa tumor cell growth, while higher level of insulin and IGFBP-1 and −2 are related to increased PCa cell proliferation. Experimental studies have shown the associations between refined carbohydrate intake and hyperinsulinemia (33). Epidemiologic studies also support the positive association between high refined carbohydrate diet and insulin resistance (34)(35)(36).…”

Dietary calcium affects body composition and lipid metabolism in rats

“…Thus it is unlikely that changes in glucose metabolism or insulin sensitivity accounted for the observed differences in serum lipids of the rats. Rats fed very low Ca (0.75Ca) had lower serum insulin compared to the other groups that may be explained by impaired secretion of insulin from pancreatic β-cells [66].…”

The protective effects of Δ9-tetrahydrocannabinol against inflammation and oxidative stress in rat liver with fructose-induced hyperinsulinemia

“…Recently, the increase in the use of refined food, which is rich fructose, has raised concerns about the potential adverse on public health. The metabolic pathway of fructose is associated with hepatic gluconeogenesis and lipid biogenesis . The main organ in metabolism, the liver transports energy to other cells in the form of glucose, lactate and lipids.…”

“…The metabolic pathway of fructose is associated with hepatic gluconeogenesis and lipid biogenesis. [8] The main organ in metabolism, the liver transports energy to other cells in the form of glucose, lactate and lipids. A large amount of fructose metabolism is in the liver.…”