If you don’t have anemia, green veggies can be a good source of iron…
But, if you are anemic – then green veggies can be a good source of irony…
Whenever I overhear conversations where someone just found out that their iron levels are low – somebody in the room is guaranteed to chime in with how important it is to “eat your greens” to boost your iron. While this type of friendly advice is well intended, it isn’t always the best suggestion for those with anemia…
As the table below highlights, a cup of cooked spinach contains over 75% of a male’s daily iron requirement, but notice how much more iron females require each day:
|Greens||Iron (mg)||% Daily Value (men)||% Daily Value (women)|
|Spinach (1 cup, cooked)||6.4||80%||36%|
|Swiss chard (1 cup, cooked)||4.0||50%||22%|
|Beet greens (1 cup, cooked)||2.7||33%||15%|
|Kale (1 cup, cooked)||2.5||31%||14%|
|Collard greens (1 cup, cooked)||2.2||28%||12%|
|Dandelion greens (1 cup, cooked)||1.9||24%||11%|
|Broccoli (1 cup, cooked)||1.1||14%||6%|
|Spinach (1 cup, raw)||0.8||10%||4%|
*Adult males need 8mg/day; adult females need 18mg/day (during pregnancy it’s 27mg!)
Popeyes’ favorite superfood, canned spinach is quite rich in iron – but this is because spinach is over 90% water, and cooks down so much that 1 cup of cooked spinach is the equivalent of 8 cups of raw spinach. Spinach may top the list of iron-rich vegetables, but a (raw) spinach salad isn’t the best option to raise up your iron levels.
Red meat is usually considered to be the best source of iron, however many types of seafood – especially canned seafood, can be equally good sources. Leaner beef cuts will have a slightly higher iron content, because leaner beef is higher in muscle than fat – and iron gets stored in muscle. In fact, the color of “red” meats partly comes from the high concentration of iron in beef (and lamb) relative to “white” meats. This fun fact also explains why darker cuts of poultry have a slightly higher content of iron than lighter cuts.
|Iron Rich Animal Foods||Iron (mg)|
|Ground beef (97/3), 3 oz||2.5|
|Ground beef (90/10), 3oz||2.3|
|Ground beef (70/30), 3oz||2.1|
|Sardines (2oz, canned)||1.7|
|Canned tuna (light, in water) 2oz||0.9|
|Chicken liver (2oz)||5.0|
|Chicken, dark meat (3oz)||1.7|
|Chicken, light meat (3oz)||1.2|
Understanding Iron Absorption (with a nightclub analogy)
You know those movies where the characters are waiting in a long line to get into the nightclub…and then the beautifully elegant VIPs show up and bypass the line and strut right into the club while everyone else waits outside? This is a helpful analogy to understand that just because there is iron in a food, that doesn’t mean that the iron will make it across the gut and into circulation.
The iron found in animal foods – such as beef, seafood, and poultry comes packaged in a heme-form of iron that has a much higher rate of absorption in our gut than plant sourced iron. I like to think of this heme-iron as “VIP-iron” with exclusive status in our digestive system, able to transport itself across the intestines into our bloodstream – just like a VIP walks right in to the most exclusive clubs.
The iron from greens (and other plant foods) hasn’t earned this VIP status, and instead needs to be carried across the intestines by a transport protein – kind of like a bouncer at the door checking IDs. Consuming grains, beans, tofu, certain vegetables, coffee, or tea will further reduce iron absorption from non-heme iron containing foods…so, the fibers and phytates in whole grains are to iron absorption what showing up at the club with an ugly friend does to your chance of getting in.
Interestingly, when you eat foods containing the “VIP” heme-form of iron (meat, seafood), it somehow enhances absorption of “Non-VIP” iron from plant sources….kind of like if you show up at the club with a VIP, you are more likely to get in too!
In summary – all the iron in those green veggies is not very likely to get absorbed into your body, just like all those poor saps waiting in line aren’t likely to get into the fancy nightclub.
Leafy greens are so ironic
As you can see in the next table – kale might have more iron on your plate, but beef and chicken puts more iron in your body. It would take 3.5 cups of kale to provide the same amount of available iron as a very small (3 oz) serving of red meat.
|Estimated range of absorption*||Iron available to body|
|Kale (1 cup, cooked)||2.5||3-8%||0.10|
|Ground beef (3 oz)||2.3||15%||0.35|
|Chicken breast (3oz)||1.0||15%||0.21|
|Spinach Salad (2 cups raw)||1.6||3-8%||0.06|
*We typically absorb about 15% of heme iron and 3-8% of non-heme iron. Consuming non-heme iron as part of a meal with fiber (vegetables), or phytates (whole grains, beans) leads to a lower absorption rate – so the above chart uses the lower end of the 3-8% range, assuming a meal with other plant foods.
So, you can get more iron from a lower iron containing food, and that is the “irony” of leafy greens!
Treating Anemia with Iron Supplements and Foods
There are quite a few iron fortified foods and iron supplements on the market, and these all contain the non-heme form of iron, so absorption is quite low, and can be further inhibited by compounds in tea, coffee, grains, and beans. Tip: take your iron supplement with a meal that contains some heme-iron (just a small amount), as this will improve absorption of the iron supplement.
My favorite iron supplements provide some vitamin C, which greatly improves absorption of the supplemental iron, as well as Vitamins B6, B12 and folic acid. These three B-vitamins are needed to boost the production of the iron-based red blood cells that transport oxygen throughout the body. Look for supplements that combine these vitamins with 18-30 mg of elemental iron, ideally in a slow-release capsule to prevent the upset stomachs that some people report from supplements.
If you are anemic – your best options are to consume some seafood or meat (even small quantities), and to consider taking an iron supplement for a month or two until your iron levels come back up. Iron absorption is also enhanced when you are anemic – as your body knows that it needs more iron, so it allows more iron to be absorbed from food until your iron levels are normalized.
One more tip to get a more iron is cooking in a cast-iron skillet, because some of the iron from the skillet is transferred into your food. You can even accelerate the amount of iron transferred from skillet to food by adding acidic foods to your dish such as tomato sauce, lemon juice or vinegar. It’s Science, Yo!!
The advice in this post is intended for the millions of people around the world with iron-deficiency anemia – the most common nutrient deficiency in the world.
Iron deficiency is less common in the US, and in fact you don’t want to have too much iron in your system. Too much iron in the body acts as a pro-oxidant (the opposite of anti-oxidant) and could potentially be a risk factor for certain cancers. Some people (especially males) regularly give blood to keep iron levels low.
In addition to green leafy veggies like spinach, kale, and chard – we can also find iron in lentils, soybeans, potato skins, quinoa, blackstrap molasses, cashews, and pumpkin seeds; and these plant sources of iron can work just fine for most of us.
So, if you don’t have anemia – then Green Veggies are a Great Source of Iron…not irony.