Low iron status and enhanced insulin sensitivity in lacto-ovo vegetarians

The efficacy of insulin in stimulating whole-body glucose disposal (insulin sensitivity) was quantified using direct methodology in thirty lacto-ovo v egetarians and in thirty meat-eaters. All subjects were adult, lean (BMI < 23 kg/m(2)), healthy and glucose tolerant. Lacto-ovo vegetarians were more insulin sensitive than meat-eaters, with a steady-state plasma glucose (mmo l/l) of 4.1 (95 % CI 3.5, 5.0) v. 6.9 (95 % CI 5.2, 7.5; P=0.0028) respecti vely. In addition, lacto-ovo vegetarians had lower body Fe stores, as indic ated by a serum ferritin concentration (mug/l) of 35 (95 % CI 21, 49) compa red with 72 (95 % CI 45, 100) for meat-eaters (P=0.0012). To test whether o r not Fe status might modulate insulin sensitivity, body Fe was lowered by phlebotomy in six male meat-eaters to levels similar to that seen in vegeta rians, with a resultant approximately 40 % enhancement of insulin-mediated glucose disposal (P=0.0008). Our results demonstrate that lacto-ovo vegetar ians are more insulin sensitive and have lower Fe stores than meat-eaters. In addition, it seems that reduced insulin sensitivity in meat-eaters is am enable to improvement by reducing body Fe. The latter finding is in agreeme nt with results from animal studies where, no matter how induced, Fe deplet ion consistently enhanced glucose disposal.