The New Complete Book of Food
by natural chemicals in the plants. Vitamin C appears to make nonheme iron more available
to your body, perhaps by converting it from ferric iron to ferrous iron, which is more easily
absorbed. Eating vitamin C–rich foods along with plant foods rich in iron can increase the
amount of iron you get from the plant—the nutritional justification for a breakfast of orange
juice and cereal or bread. (See also beans, bread, flour, oats, wheat cereal.)Adverse Effects Associated with This Food
Flare-up of aphthous ulcers. In sensitive people, eating citrus fruits may trigger an attack of
aphthous ulcers (canker sores), but eliminating citrus fruit from the diet neither cures nor
prevents canker sores.
Contact dermatitis. Although there is ample anecdotal evidence to suggest that many people
are sensitive to natural chemicals in an orange’s flesh or peel, the offending substances have
never been conclusively identified.Food/Drug Interactions
Aspirin and other nonsteroidal anti-inflammatory drugs (ibuprofen, naproxen, and others). Tak-
ing aspirin with acidic foods and drinks such as oranges or orange juice may make the drugs
more irritating to the stomach.
False-negative test for hidden blood in the stool. The active ingredient in the guaiac slide test
for hidden blood in feces is alphaguaiaconic acid, a chemical that turns blue in the presence
of blood. Citrus fruits or vitamin supplements containing more than 250 mg ascorbic acid
may produce excess ascorbic acid in the feces, which inhibits the ability of alphaguaiaconic
acid to react with blood may produce a false-negative test result that fails to disclose the
presence of a tumor in the colon.