The New Complete Book of Food
plantain may reduce the risk of stroke. In the study, the men who ate the higher number
of potassium-rich foods (an average of nine servings a day) had a risk of stroke 38 percent
lower than that of men who consumed fewer than four servings a day. In 2008, a similar
survey at the Queen’s Medical Center (Honolulu) showed a similar protective effect among
men and women using diuretic drugs (medicines that increase urination and thus the loss
of potassium).Adverse Effects Associated with This Food
Nitrate/nitrite poisoning. Spinach, like beets, celery, eggplant, lettuce, radish, and collard
and turnip greens, contains nitrates that convert naturally into nitrites in your stomach and
then react with the amino acids in proteins to form nitrosamines. Although some nitro-
samines are known or suspected carcinogens, this natural chemical conversion presents
no known problems for a healthy adult. However, when these nitrate-rich vegetables are
cooked and left to stand at room temperature, bacterial enzyme action (and perhaps some
enzymes in the plants) converts the nitrates to nitrites at a much faster rate than normal.
These higher-nitrite foods may be hazardous for infants; several cases of “spinach poison-
ing” been reported among children who ate cooked spinach that had been left standing at
room temperature.Food/Drug Interactions
Anticoagulants Spinach is rich in vitamin K, the blood-clotting vitamin produced natu-
rally by bacteria in the intestines. Consuming large quantities of this food may reduce the
effectiveness of anticoagulants (blood thinners) such as warfarin (Coumadin). One cup of
drained canned spinach contains 988 mcg vitamin K, 16 times the RDA for a healthy adult;
one cup of shredded raw spinach contains 144 mcg vitamin K, nearly three times the RDA
for a healthy adult.
MAO inhibitors. Monoamine oxidase (MAO) inhibitors are drugs used as antidepressants
or antihypertensives. They interfere with the action of enzymes that break down tyramine,
a chemical produced when long-chain protein molecules are broken into smaller pieces.
Tyramine is a pressor amine, a chemical that constricts blood vessels and raises blood pres-
sure. If you eat a food rich in tyramine while you are taking an MAO inhibitor, the pressor
amine cannot be eliminated from your body and the result may be a hypertensive crisis
(sustained elevated blood pressure). There has been at least one report of such an interaction
in a patient who consumed New Zealand prickly spinach while using an MAO inhibitor.