Submitted to: Journal of the American College of Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/17/2006
Publication Date: 6/1/2007
Citation: Joung, H., Jeun, B., Li, S., Kim, J., Woodhouse, L.R., King, J., Welch, R.M., Paik, H. 2007. Fecal phytate excretion varies with dietary phytate and age in women. Journal of the American College of Nutrition. 26(3):295-302. Interpretive Summary: Phytic acid (myo inositolhexaphosphoric acid) is known to inhibit the bioavailability of iron and zinc to humans. Edible whole cereal grains and legume seeds contain high concentrations of phytic acid. Iron and zinc deficiencies afflict over 2 billion people globally especially the resource poor dependent on cereal grains and legume seeds for their sustenance. Many of those afflicted are thought be the result of the consumption of high concentrations of phytic acid from these food crops. We studied the effects of age in women on fecal phytic acid excretion to determine if the consumption of high phytic acid meals for long periods of time would result in increased ability to digest the phytic acid. Our results indicate that phytic acid degradation in the gut is substantial and more variable in young women with older women degrading more phytic acid compared to young women. These results suggest that long-term phytic acid consumption may lead to the ability to degrade more phytic acid in the gut. Further studies are warranted to determine both beneficial and adverse effects of phytic acid consumption that consider both long-term phytic acid intake and age of subjects as well as dietary phytic acid levels. Apparently, phytic acid may have less inhibitory effect on mineral bioavailability than previously assumed.
Technical Abstract: In young and elderly women consuming two different levels of dietary phytate, fecal phytate excretion was affected significantly not by dietary phytate alone but by age of subjects and the interaction of age and dietary phytate. Young subjects had higher fecal excretion than elderly subjects and were influenced by the phytate level in the diet. The elderly women, who are considered to have consumed high phytate diets for a long time, seem to have higher capacity for degradation of dietary phytate. The results imply that considerable amounts of dietary phytate are degraded in the gastrointestinal tract decreasing the adverse effects of phytate on mineral absorption and providing utilizable phosphorus. These findings suggest that dietary phytate may have less inhibitory effect on the mineral absorption than previously assumed.