The effect of high and low glycemic index diets on urinary chromium in healthy individuals: a cross-over study.

BACKGROUND Insufficient dietary intake of chromium as an essential nutrient leads to signs and symptoms that are similar to those observed for diabetes and cardiovascular diseases. We postulate that in healthy individuals, urinary chromium excretion following a high glycemic index diet is higher than after a low glycemic index diet. METHODS A sequential randomized controlled cross-over study was carried out at the Metabolic Unit of Nutrition Department of King's College London. Sixteen healthy individuals aged 18 - 60 years were recruited from 26 volunteers. A low or high glycemic index diet (as the main meals/day) was given to the volunteers over six days. Fasting blood glucose and insulin changes were determined and 24-hr urine samples were collected to measure chromium excretion before intervention and every second day within each treatment with a one wash-out period using Dynamic Reaction Cell Inductively Coupled Plasma Mass Spectrometer. RESULTS During the six-day diet study, there were no significant differences in 24-hr urinary chromium losses between the two groups following the low glycemic index (0.58+/-0.08 microg/24 hr) and high glycemic index diets (0.48+/-0.06 microg/24 hr). However, during day six there was a trend towards greater loss of chromium after the high glycemic index diet (0.73+/-0.1 microg/24 hr) in comparison with the low glycemic index diet (0.54+/-0.07 microg/24 hr). CONCLUSION Evidence that urinary chromium loses following the high glycemic index diets have not been clearly demonstrated in normal subjects. These results suggest that chromium excretion may need to be observed for longer than six days to address this question.