Jul 242018

When Spinach is NOT a Good Source of Iron

When Spinach is NOT a Good Source of Iron

Iron deficiency anemia is the most common nutrition deficiency in the United States. If you have been told you, or a family member needs more iron, you are not alone.

Why Iron Deficiency is so Common

When you get the news from your doctor to increase your intake, one of the first things you do is head to Google to search good sources of iron in food. However, the reason iron deficiency is so common is not because it is scarce in the food supply, it is because it is one of the hardest minerals to absorb.

I’m sure you are wondering what I mean by absorb. Don’t we absorb everything we eat? The answer is no. We poop because we do not absorb everything we eat. While iron is essential for life, if there is too much in the body, it causes the liver to fail. If the liver fails, one of two things will happen, you will get a liver transplant or you will die.

Now, let’s say that a person does have too much iron in the body and the liver is suffering, but it has not failed yet. How does the body eliminate the extra iron? The only way to eliminate iron once it makes its way to the liver is by blood loss. Wait, did I just say by blood loss?! Yes, I did. Clearly, this would take medical intervention. Don’t worry, nothing weird involving leeches is part of this, think regular blood donation, but still invasive and time consuming.

Stepping back and looking at this from a biological standpoint, and the fact that the human body was created with amazing self-preservation systems, what would be the easiest way to protect the liver from iron toxicity? The answer is to prevent the iron from ever being absorbed into the bloodstream. To the body, that means, pooping out a large amount of what is ingested.

The good news though, nutrition science has provided some key understandings. First, the type of iron which most readily absorbed (yes, there is more than one). Second, dietary factors that promote absorption. Finally, the factors that inhibit absorption. When trying treat iron deficiency, it is imperative that all of these are taken into consideration.

Heme iron vs non-heme iron

Heme iron is found in animal products. It is the iron of red meat. This form of iron is the most easily absorbed. When I’m working with someone who has iron deficiency anemia, finding ways to increase heme iron intake is my first goal.

Non-heme iron is found in non-animal products. This is the iron of spinach. Non-heme iron is difficult for the intestines to absorb. Why though? It is because the non-heme iron requires more biochemical changes prior to absorption than does heme iron. The more steps you introduce to a process before the iron is even absorbed into the intestines the greater the likelihood that some of the iron will be missed, and therefore go through the intestines unabsorbed. In other words, you poop it out.

Dietary factors that promote absorption

Even though heme iron is my first line of attack on iron deficiency, I know that other foods also contain the mineral. I would be crazy to not do everything possible to help the body absorb any and all it can, right? This is where promoting non-heme iron absorption turns into a fun menu planning exercise. Iron has more than one biochemical state. The ferrous form is most readily absorbed. The ferric form is pretty much eliminated. The ferrous form can turn into the ferric form once inside the gut (oh that is just super helpful, huh?). To help the iron stay in the absorbable ferrous form, Vitamin C becomes our best friend. Vitamin C is a potent antioxidant, and we put that characteristic to work here. If you have ever purchased an iron supplement you may have noticed that the label says ferrous sulfate and Vitamin C. Combining the iron and Vitamin C in one pill increases the absorbability of the supplement.

MPF factor, literally means: meat, poultry, fish factor. It is a currently unidentified compound found in meat, poultry, and fish that increases non-heme iron absorption. Did I just say that, in addition to heme iron being the best absorbed iron, animal products have another compound that increases other types of iron absorption? Yes, yes, I did.

Being iron deficient actually enhances absorption as well. I know this statement is completely baffling on its face, but bear with me as I explain. When a person is NOT deficient, only about 10-20% of ingested iron is absorbed. When deficiency exists, this amount can go as high as 30-35%. When the body is deficient in a nutrient it does try to absorb more, but think about it – even in a deficient state, the body is only absorbing about a third of the iron consumed.

Dietary factors that inhibit absorption

Polyphenols found in tea and coffee, oxalic acid found in tea and spinach, and phytates found in spinach and legumes are all compounds that inhibit iron absorption. There are many people who healthfully follow a vegetarian diet and do not experience iron deficiency anemia. Those people are effectively absorbing iron from non-heme sources, so concerns about these inhibitors do not apply to that group. As a Dietitian, I am concerned about these factors when facing a diagnosis of iron deficiency. Deficiency can be a challenging hurdle to overcome, and I want to minimize barriers as much as possible. Please hear me say, that I am not advocating avoiding these foods, I am advocating not promoting the use of spinach and legumes to overcome iron deficiency. When dealing with an iron deficiency, these foods can certainly be included in the diet, and if combined with enough MPF and Vitamin C, there may even be some absorption.


Now, I’m going to level with you, as a Dietitian, I hate iron supplements. Iron supplements are torture on the gut. They cause both nausea and constipation. It is not uncommon for a stool softener to be needed while on iron supplementation. If someone struggles with constipation due to other issues, iron supplements may lead to the need for additional laxative use. It is a vicious downward spiral when you start requiring drugs to treat the side effects of other drugs. Even if you don’t need extra medication for your gut, the side effects of the iron alone make it a miserable supplement.

When I would get consults to see patients about iron deficiency anemia, my very first question was, “Are you a vegetarian?” I have no opposition to being vegetarian or vegan, but with the difficulty in absorbing non-heme iron, coupled with lack of MPF, I knew I only had one true viable option for helping vegetarian patients. That was supplementation.

I never lied to my patients, I told them the side effects of supplementation, but I also told them some things to look for in choosing a product. First of all, you want a pill that states it has an enteric coating. This protects the stomach from irritation. Secondly, you want to find product that has Vitamin C to promote absorption.

There are liquid supplements for children and those who cannot swallow a pill. Again, these are torture on the gut. They also taste absolutely terrible. However, if we are dealing with severe anemia, this may be our best option.

How to Eat for Iron Deficiency Anemia

So what are some of my favorite foods to suggest when trying to treat iron deficiency? Spaghetti with meat sauce, especially with meatballs is an awesome kid-friendly meal. Steak salads with lots of vegetables. Grilled chicken breast sandwiches with tomato slices. It boils down to finding ways to combine meat with vegetables and/or fruit in the same meal. This allows for heme iron, MPF, and Vitamin C to help with absorption of all non-heme sources to be combined into one meal.

Once I explain the basis of the meat/vegetable/fruit combination, I start asking lots of questions about favorite foods in these categories. I can sit and come up with iron rich meal plans all day long, but if I choose foods that you hate, how likely are you to eat it? So sit down and start writing out all favorite foods in these categories. Next, think of favorite recipes that combine these ingredients. Plan to incorporate these frequently into your meal planning. Look at lunch meals. Salads and sandwiches are common lunch meals. Can you throw a little MPF into that salad by adding salmon?

Kids and Iron Deficiency Anemia

Many cereals are iron fortified. This is a non-heme source, similar to a supplement. For parents who have a picky eater for a kid (like me), cereal is often a fight-free food. Having a few foods that aren’t a battle are often a lifesaver. If this is you, just try to see that the cereal is eaten with some fruit or even just a small amount of 100% juice to have some Vitamin C with the meal.

Finally, I want to note the importance of limiting toddlers and kids to 24oz of cow’s milk per day. Amounts in excess of this can cause tiny bleeds in the intestines that can cause or worsen anemia. This limitation does not apply to breastmilk or formula. Breast milk, while it does not contain large amounts of iron, it is the best absorbed of all iron sources.

I know it can be concerning to be hear the words iron deficiency, but try not to stress. Remember it is very common, and there are ways to treat it.


Authentic Moment: Post may contain affiliate links. If you purchase through this link it will not cost you more, but I may earn a small commission.