Restoration of thiamine status with white or whole wheat bread in a thiamine-depleted rat model

Long-term thiamine deficiency has been largely documented, whilst little is known about effects of short-term depletion/repletion periods on thiamine vitamers status. Rats were submitted to short-term depletion (8 days) followed by different durations of repletion (3 or 14 days) with thiamine from bread (whole wheat bread or white bread, whole B and white B respectively) or corresponding controls. Short-term depletion drastically decreased plasma thiamine (-97%) and its urinary excretion (-77%). TDP (thiamine diphosphate) was strongly affected in liver (-67%) but less affected in cerebellum (-38%) or kidneys (-45%). Short-term repletion (3 days) with whole B diet or its control restored TDP at initial values in cerebellum and kidneys. A longer repletion (14 days) was required to restore liver TDP. Comparison of the diet groups indicates that thiamine status in tissues of rat fed whole B or white B diet was comparable to that of rats fed purified thiamine. Plasma thiamine concentration could not be restored at initial values in the bread groups or respective controls. In conclusion, thiamine in whole wheat bread appears effective in preventing marginal deficiencies and plasma thiamine is a less reliable indicator of thiamine status than tissue TDP levels.