Ask the Diet Doctor: Are Plants or Meat Better Sources of Iron?
Whether you're a vegetarian or a meat-eater, iron rich foods are crucial to your diet. Our diet expert weighs in on whether your sources of iron really matter
You probably spend most of your time thinking about protein, fat, and carbs, but there's another nutrient that needs your attention: iron. Approximately seven percent of adult Americans are iron-deficient, with upwards of 10.5 percent of adult women suffering from iron deficiency. Iron not only affects your energy levels, but can also compromise your workout. (5 Weird Signs You Could Have a Nutritional Deficiency)
First of all, it's important to know that dietary iron is available in two forms: heme and non-heme. The primary source of dietary heme iron is red meat (like lean beef), but heme iron is also found in poultry and seafood. Non-heme iron is primarily found in spinach, lentils, white beans, and foods that have been fortified with iron (like refined grains).
So, is one of these sources of iron better for you? Probably not. And the reason has to do with how your body processes iron after it's absorbed.
Heme iron is more readily absorbed than non-heme iron due to a protective structure called a porphyrin ring. This ring prevents other compounds in the digestive tract, like vitamin C and certain antioxidants, from impacting iron and absorption. Other research shows that the chemical makeup of meat proteins can further enhance the absorption of heme iron. This increased absorption is the main reason the Dietary Guidelines for Americans emphasizes heme sources as the focus for iron-deficient young and pregnant women. (6 Foods That Are Off-Limits During Pregnancy)
On the other hand, non-heme iron absorption is greatly impacted by other compounds present at the time of digestion. Vitamin C enhances non-heme iron uptake by your body, while polyphenols-a type of antioxidants found in tea, fruit, and wine-inhibits non-heme iron uptake.
After this, it's all relatively the same to your body. When heme iron is absorbed by your intestinal cells, the iron is quickly extracted and put into an iron holding tank (called the labile iron pool by scientists) until it is ready be transported out of your intestinal cells and into your body. Non-heme iron has a similar fate: It's also pulled by the intestinal cells and dumped into the iron holding tank. When the time comes for the non-heme iron to be used, it leaves the intestinal cell and is put into circulation in your body. By this point, the body has no means of determining if the iron being put into your circulation came from spinach or a steak as all the iron has been jumbled around inside your intestinal cells.
If you need more iron in your diet-and chances are you might-then you shouldn't feel like you need to force yourself to eat liver and pop iron supplements. (Are Iron Supplements the Kick Your Workout Needs?) You can get iron from a lot of places both plant and animal sources such as fortified cereals, certain types of seafood (clams, oysters, octopus, mussels), coconut milk, tofu, lean beef, mushrooms, spinach, beans, and pumpkin seeds. And while some foods are richer sources of iron than others, don't get too hung up on heme and non-heme sources as much as ensuring your iron comes from whole, healthy foods.