Older Women May Need More Zinc
~ November 1997 No.24 ~
Dietary intakes of the mineral zinc has often been reported to be low in the general population, and this is especially true for elderly women.
In a recent scientific article published in the American Journal of Clinical Nutrition the risk of older women to zinc deficiency has been raised. The team of researchers from the Mineral Bioavailability Laboratory at Tufts University in Boston pointed out that based on their research, post menopausal women who increase their calcium intake, may at the same time be decreasing their absorption of zinc and thereby increasing their risk of zinc deficiency. Many older women have increased their calcium intake in an attempt to slow down osteoporosis, a bone thinning disease that is particularly prevalent in this population.
In the experiment, post-menopausal women were given a control diet or a diet containing added calcium either in the form of a tablet or in the form of milk. The controlled feeding experiment lasted 36 days. The Boston researchers found that when the women ate the diet containing added calcium, the overall absorption of zinc was lowered. This effect of added calcium was similar no matter if the calcium was supplied as a tablet or milk. It appears the scientific community is still not clear about all the factors that influence zinc uptake, storage, use in the body and excretion. The authors of this study state that their results suggest that high intakes of calcium can reduce zinc absorption and zinc balance in the body. However, they point out that longer duration studies need to be carried out to assess the long term effects of calcium on zinc status.
The current US recommended daily allowance (RDA) for zinc in adult women is 12 mg / day, and it has been recommended that elderly people consume 1500 mg of calcium per day as a way of reducing bone loss. The authors of this latest study on zinc suggest that an additional 10 mg / day in zinc may be required to overcome the loses caused by dietary calcium.
|Good Dietary Sources of Zinc:||liver, kidney and muscle meats|
|Biochemical Role of Zinc:||zinc is an essential part of more than 100 different enzymes in the body|
|Plant Sources of Zinc:||most plant sources are not good sources of zinc because the plants also contain phytate which binds the zinc and makes it unavailable as it passes down the digestive tract|
|Zinc deficiency symptoms:||include loss of appetite, retarded growth, dermal changes and reduced immune function, delayed wound healing|
High dietary calcium intakes reduce zinc absorption and balance in humans
Am J Clin Nutr. 1997,65:1803-9