You Ask, I Answer: Iron Cookware

Any data out there on the amount of iron transferred into food when cooking with cast iron cook ware?

Does the act of seasoning the cast iron (coating it in oil) prevent or diminish iron's capacity to leach into food during cooking?

-- Nicole Journault
[City Unknown], Canada

One of the most thorough studies on this topic, conducted by Brittin and Nossaman, was published in 1986 in the Journal of the American Dietetic Association.

The conclusion? "Acidity, moisture content, and cooking time of food significantly affected the iron content of food cooked in iron utensils."

It is a well established fact that cooking in cast iron cookware will transfer some iron into your food, especially if the food contains high amounts of vitamin C and moisture and is stirred or turned over frequently.

In terms of figures, cooking half a cup of spaghetti sauce in an iron pot for 15 minutes increases its iron content by approximately 800 percent. Foods low in moisture and vitamin C, however, increase by anywhere from 80 to 150 percent.

Keep in mind that these figures depend on how long you cook these foods for.

The "catch 22" is that iron cookware often imparts a strong metallic taste to foods -- especially those high in vitamin C and moisture cooked for long periods of time!

Three more important points:

1) Coating the cookware in oil prevents iron's leaching capacities.

2) Iron absorption gradually decreases with each passing use.

3) Since iron cookware only increases the iron content of non-heme iron, meats are unaffected.

You Ask, I Answer: Iron Absorption

I found your post about calcium absorption from different foods really interesting.

Are there other vitamins or minerals where that happens?

-- Nancy (last name withheld)
Coral Gables, FL

Yes -- let's talk about iron!

The highest iron absorption rate occurs with beef -- of which our bodies absorb approximately 20 percent.

Poultry and pork are relatively close, averaging anywhere from 15 to 18 percent absorption.

When it comes to foods like beans and spinach, though, our bodies only take up 2 percent!

Fish falls somewhere in between -- roughly eight percent of the iron in boiled fish is absorbed, but that figure is slightly increased if you're talking about canned tuna fish.

Remember -- heme iron (found in animal products) is more absorbable than non-heme iron (from plant foods).

Here is some interesting -- and little-known -- iron trivia:

The Dietary Reference Intake for iron is 8 milligrams for adult men ages 19 - 50 and 18 milligrams for adult women in that same age group, but those figures tell very little of the real story.

Truth is, we only need anywhere from 0.5 to 2 milligrams of iron a day.

However, to absorb those amounts, we need to consume anywhere from 8 to 18 milligrams of iron in our food.

Since food labels only display the total iron in a food (rather than what is actually absorbable), the Dietary Reference Intakes take this into account.

More importantly, though, those DRIs are strictly for omnivores.

Vegetarian men ages 19 to 50 should aim for 14 milligrams a day (remember, we are talking total/food label figures here), while women of that same age should be getting 33 milligrams per day!

A vegetarian diet does not in and of itself cause anemia; vegetarians simply need to eat higher amounts of non-heme iron to supply the body with sufficient quantities of this mineral.