Web edition: October 2, 2002
Iron deficiency, the most common nutritional disorder in the world, is a major problem in many developing countries. The World Health Organization (WHO) currently estimates that a mind-boggling 4 to 5 billion people may suffer from some form of iron deficiency—that's 66 to 88% of the world's population. Up to 2 billion of these people also suffer from anemia, a condition often due to insufficient iron in which blood has too few red blood cells.
Now, a new study, which tested iron uptake from recipes including Chinese cabbage, adds to the evidence that iron cooking vessels may be a cheap and effective way to fight deficiency of the micronutrient in developing countries.
Anemia, which increases peoples' susceptibility to other diseases, is associated with reduced work productivity and economic output. WHO estimates that effectively tackling iron deficiency could boost productivity by up to 20% in many developing nations.
The major reason for iron deficiency is the naturally small amount of iron in plant-based foods—such as rice and cassava—which are staples in rural areas of the developing world, says physiologist Raymond Glahn of the USDA Agricultural Research Service's Plant Soil and Nutritional Laboratory at Cornell University in Ithaca, N.Y.
Glahn and his collaborators, Shumei Yun and Jean-Pierre Habicht of Cornell University, now provide evidence that reduced iron deficiency in some areas of China may be due to the traditional use of iron cookware.
Recent surveys showed that in most parts of China, up to 40% of the population has anemia. However, says Glahn, these surveys also showed that in some poor, rural areas of northwest China there was a relatively low prevalence of the condition—18.2% in children and 9.4% in women. This was unexpected since people in the northwest eat a similar diet and, in general, are as poor as people where anemia is endemic.
The scientists proposed that the regionally specific use of iron pots and also consumption of rice vinegar and fermented cabbage in large quantities might be responsible for the lower prevalence of iron deficiency. Vinegar and acidic fermented foods are known to increase the rate at which iron leaches from pots, says Glahn.
To test their idea, the scientists used either aluminum or iron vessels to cook three of the most frequently consumed regional dishes: fresh Chinese cabbage, fresh Chinese cabbage with vinegar, and fermented Chinese cabbage, a type of sauerkraut. Fermented cabbage is prepared by keeping sealed containers of cabbage and water at room temperature for about a month.
Previous studies have proved that cooking in iron pots increases the amount of iron in food, says Glahn. But since the body absorbs some types of iron more readily than others, this finding doesn’t necessarily indicate a boost in the amount of iron taken up.
To get a more accurate picture of how much iron the body might absorb from the cabbage dishes, the researchers used what they call an artificial gut. The model system, which Glahn developed, mimics the biochemical conditions of the human intestinal tract and permits nutrients to be absorbed by human intestinal cells, known as Caco-2 cells, which have been grown in the laboratory.
The amount of iron available to the body is estimated by measuring how much of an iron storage protein called ferritin forms in the Caco-2 cells during artificial digestion.
The researchers found that in experiments with all three dishes, the amount of iron that the body could absorb was significantly higher when iron cooking vessels, rather than aluminum ones, were used. The researchers also found that the available iron content was significantly higher in both the fermented and vinegar-cooked fresh cabbage than in the vinegar-free fresh cabbage. The researchers plan to publish their study later this year.
Epidemiological studies have also provided evidence for the benefits of iron cookware. One 8-month study in 1998 showed that 22 Brazilian infants whose food was cooked in iron pots had significantly higher concentrations of iron in their blood than 23 infants whose food was cooked in aluminum pots. In the aluminum-pot group, 74% of the children suffered from anemia, in contrast to only 36% in the iron-pot group.
In 1999, a 3-month study of Ethiopian infants found that children fed food cooked in iron pots also had lower prevalence of anemia and better growth than children fed from aluminum pots did (SN: 3/13/99, p. 175).
"Cooking with iron pots could be an effective way to prevent iron deficiency anemia if an appropriate cooking method is used," say Glahn and his team in their unpublished paper. "However, in recent years, the utilization rate of iron pots has decreased in some developing countries." Aluminum pots are becoming an increasingly attractive alternative, in part because of their low weight and anticorrosion properties, say the researchers.
Raymond P. Glahn
U.S. Plant Soil and Nutrition Lab, USDA/ARS
Ithaca, NY 14853
1999. Iron in the bowl. Lancet 353(Feb. 27). Article.
1992. For more iron, elevate that cow. Science News 133(March 5):153.
Seppa, N. 1999. Iron pots help fend off anemia. Science News 155(March 13):175.
Information from the World Health Orgnization on battling iron deficiency anemia can be found at [Go to].