Iron deficiency in teens
Iron deficiency anemia (IDA) is a common problem seen mostly in menstruating women and frequently in teenage girls. I’ve supported a number of young women with iron deficiency this year and thought it might be time for a PSA on the topic. This type of anemia can lead to fatigue, hair loss, weight gain as well as learning cognitive difficulty… so it’s important to stay on top of it.
“It is estimated that 9-16% of US female adolescents are iron deficient while 2-5% are anemic.”
What is anemia?
Anemia refers to a state of having low number of red blood cells or low hemoglobin levels in the blood. The different kind of anemia include iron-deficiency anemia, pernicious anemia, aplastic anemia, and hemolytic anemia. The first 2 are due to nutritional deficiencies, low iron and low B12, respectively. We’re just going to zoom in on the iron-deficiency anemia here.
Is anemia caused by low iron?
Yes. Iron deficiency is typically caused by low iron intake. It can also be caused by not absorbing what you eat or heavy bleeding. Whatever the cause, iron-deficiency anemia is a low-iron state.
I see this a lot in teenage girls who are menstruating and do not eat a balanced diet. These are the people I want to focus on, screen for iron deficiency, and support.
Picky eaters and teens choosing a vegetarian diet (but not a balanced vegetarian diet) are at the highest risk of iron deficiency. If you have a daughter who has not started menstruating yet, and she does not eat very well (very particular, doesn’t like meat, eats only starches and fruit), she could really struggle once she starts bleeding.
A little prevention could go a long way here. If you suspect the pre-teen girl in your life has a diet that is low in iron, talk to your pediatrician about having a complete blood count and iron panel run. If they are even borderline anemic, you will want to start looking into improving their diet or supplementing. Because it’s not going to get any better in the coming years.
What labs should I ask for?
A CBC is a routine lab that will flag anemia. Get this one done if your diet is poor and there is fatigue or other symptoms.
The iron panel and serum ferritin should be requested if red blood cells (RBC) or hemoglobin (HGB) come up low (or nearly low). Of course, if there are already clear signs and symptoms of iron deficiency, ask for an iron panel upfront. (4)
What are the symptoms of iron deficiency?
Fatigue
Weakness
Pale skin
Shortness of breath
Headache
Dizziness or lightheadedness
Cold hands and feet
Numbness of extremities
Sore tongue
Brittle nails, split or spoon-shaped nails
Pica (unusual cravings for non-nutritive substances like ice and dirt)
Poor appetite
Can I treat myself for iron deficiency?
I would get some guidance on this. Too much iron is as dangerous as too little. It’s best to see your doctor and get some labs done. Not only to confirm anemia but also to start determining the CAUSE. Sometimes anemia is caused by iron deficiency, but it can also be caused by low copper, low B12 or low folate. Or it could be caused by infection and heavy bleeding so other strategies need to be employed. So the first step is to see which nutrient is lacking. THEN determine the cause. This typically involves coordination between your primary care provider and a nutrition professional.
What are the causes of iron deficiency?
Low intake
Excess bleeding
Chronic infection
What can untreated iron-deficiency lead to?
Untreated iron-deficiency is serious.
Low iron can lead to poor cognitive function and can impair learning in your teen, just when they need it the most. Studies have demonstrated impairments in attention span, intelligence, and sensory perception.(5)
Low iron can also lead to low thyroid hormone production. The thyroid gland needs iron to make thyroid hormones. So this can really slow down your metabolism leading to constipation, weight gain, brain fog and more. So… yes… low iron can lead to weight gain.
What form of dietary iron is best abosrbed?
There is nuance in this answer. First, there are 2 forms of iron: heme and non-heme. Heme iron is much more readily absorbed by our bodies than non-heme. Heme iron is only found in animals. Non-heme iron is found in both plants and animals.
We also need to take into account anti-nutrients. These are things like phytates and oxalates that bind up cations like iron (and calcium, magnesium, zinc, manganese…) and render them useless to our bodies. Oxalates and phytates are found in plant foods like spinach, chard, rhubarb, beets, whole grains, beans and other seed foods. While these plant foods have plenty to get excited about, their iron is less bioavailable than that found in animal sources. (6)
There are some strategies to improve our absorption of iron. One is to include acidic food/drink with our iron sources. Think of having a salad with a vinegarette dressing, a tablespoon of apple cider vinegar before meals, or some lemon in your water.
For most of us, a combination of heme and non-heme sources works best for the usual reason… variety. Each food source has other nutrients we need and variety helps us meet all our other needs as well. But if there is a nutrient deficiency we are trying to CORRECT, a therapeutic period of eating more heme sources (meat) may be helpful for 3-6 months.
What are good iron sources?
Plenty of foods contain iron. The problem is that a lot of that won’t be absorbed. Heme iron is optimal. Non-heme is not only poorly absorbed, the foods that contain it also have anti-nutrients like phytate and oxalates as well as polyphenols that further reduce absorption.
Other tricks you might not have heard of are using a cast iron skillet and eating sea vegetables like dulse
Do heavy periods cause anemia?
Yes… and anemia can cause heavy periods. So if you have a teen with heavy periods, keep an eye on their iron levels. If you have a girl in your life who has heavy bleeding AND isn’t eating a really nutritious diet, she should probably get labs done every year.
It can take years for menses to even out into a regular cycle. Similar to the way menopause can be a little all over the place as our periods are fading away, they are also pretty erratic when starting up. Girls don’t know what “normal” bleeding is, so ask them questions like how many pads they soak through in a day and how many days it’s heavy vs light. Women’s health expert Dr. Aviva Romm explains that it’s often a sign of hormone imbalance (either high estrogen or low progesterone). It can also be something more serious so it should never be ignored. Most women will go through their whole life just putting up with heavy bleeding and low iron. At some point, it gets so bad that they end up getting a hysterectomy. But you don’t have to just put up with it. The heavy bleeding is also a sign something is out of balance and you’ll benefit from doing your due diligence to find out what that is. If we suspect this, I typically run a DUTCH test to evaluate hormone levels. Testing often illuminates a path forward that provides relief. For example, if progesterone is low, we can work on strategies to increase it or talk to your doctor about bioidentical hormones. If estrogen levels are too high, then we look into ways of clearing them from your body more efficiently.
Here’s the bad news about low iron and heavy bleeding. They cause a vicious cycle. Heavy bleeding can cause low iron and low iron can lead to heavy bleeding. Crazy, right? Nearly 40% of women of reproductive age experience heavy menstrual bleeding. In some studies, only 22% of these women sought medical advice for it. (7)
I encourage you to take heavy menstrual bleeding seriously. But testing is always a good idea before adding hormones or even supplements that affect hormones like DIM and calcium-D-glucarate. You could just be making the situation worse if you guess wrong. The first thing I’d do is run a DUTCH hormone test for you.
Anemia of chronic disease
Sometimes we can’t blame iron deficiency on poor diet or heavy bleeding. If you’re reading through this thinking, “I eat plent of good iron sources and my periods aren’t that heavy!” Then it’s time to consider other causes. Chronic infection is next on my list.
There are 2 ways that chronic infection can cause iron deficiency.
One is the classic way. Infections and other chronic medical conditions that increase inflammation signal the iron to be sequestered into the storage form (ferritin). So you will have elevated ferritin levels but there are signs of anemia. This is the anemia of chronic disease. You’ll see this when you’ve got low red blood cells (RBC) and hemoglobin (HGB), but your ferritin levels are high. More dietary iron is not the solution - it just pours gas on the fire. Resolution of the infection is the solution. In this case, I’d be looking into dental infections, gut infections, food intolerances and other chronic illnesses.
Small intestinal bacterial overgrowth (SIBO) is one such infection. SIBO is often the cause of irritable bowel syndrome (IBS). It’s when your awesome microbiome from your LARGE intestine move up into your SMALL intestine and start eating all of your food. They love iron. (Read more about how SIBO can cause iron deficiency.)
Are iron infusions safe?
Yes, they are.
Let’s be clear… an iron infusion is different from a blood transfusion. It’s easy to mix them up.
Iron infusions sound very drastic and scary. But they can be real life-savers and they work fast. If your iron has become so low that you are experiencing profound fatigue, it can be a good idea for a few reasons. One, while it’s ideal to get your iron via the oral route (food or supplements), oral iron supplements often cause constipation and other gastrointestinal symptoms. Two, you might not be absorbing iron (because of SIBO, Celiac disease, pernicious anemia, or other). Three, you can get your iron levels up more quickly this way. In recent years, new forms of intravenous iron therapy have come on the market which is much better tolerated than the old versions. (8)
It will still take your body a few months to use that iron to make enough red blood cells to get you back to your old self again. Waiting on a few steak dinners might not get you there fast enough. Your doctor may recommend a few infusions in a row, and follow-up labs 6-weeks later to see that they have corrected the deficiency. Be sure to add the other blood-building nutrients to help the iron with either a balanced diet or supplements and keep that lab appointment.
The other nice thing about infusions is that it allows us to see if your body will respond to iron, even if you can’t absorb it. Think about it this way, if you’re eating red meat three times per week and STILL have iron deficiency anemia, but an iron infusion directly into your bloodstream helps your body make new red blood cells, then the problem is in your gut. That really helps us zero in on our next move. My next move would be to suspect low stomach acid or… more likely… SIBO.
What’s the best iron supplement?
Iron supplements can be tricky. A lot of them can cause stomach upset and constipation. It also turns your stool black. The sources of iron in supplements tend to be ferrous fumarate, ferrous gluconate, ferrous sulfate. Ferrous bisglycinate appears to be equally bioavailable as ferrous sulfate but with fewer gastrointestinal side effects. (9,10)
Liver capsules are also an option. You can buy liver capsules, which will not only contain bioavailable iron, but also the accessory nutrients needed to build more red blood cells. The downside is you need to take a lot of them and they can be expensive.
For best absorption, take iron supplements at least 30 minutes before a meal. If it causes stomach upset, take it with a small amount of food, but avoid taking it with milk, calcium, antacids, high-fiber food or caffeine. (4)
The body tightly regulates iron absorption to the point that taking more does not equal more iron in the body. You go low and slow. Higher, more frequent dosing just leads to more gastrointestinal symptoms. Dosing 60-120mg iron with some vitamin C or other acid every other day seems to be an optimal oral dosing regimen with iron deficiency present. (11)
References
Centers for Disease Control and Prevention. Recommendations to prevent and control iron deficiency in the United States. MMWR Recomm Rep. 1998 Apr 3;47 (RR-3):1-29.
Looker AC, Dallman PR, Carroll MD, Gunter EW, Johnson CL. Prevalence of iron deficiency in the United States. JAMA. 1997 Mar 26;277(12):973-6.
Cogswell ME, Looker AC, Pfeiffer CM, Cook JD, Lacher DA, Beard JL, Lynch SR, Grummer-Strawn LM. Assessment of iron deficiency in US preschool children and nonpregnant females of childbearing age: National Health and Nutrition Examination Survey 2003-2006. Am J Clin Nutr. 2009 May;89(5):1334-42.
Nguyen M, Tadi P. Iron Supplementation. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK557376/
I Jáuregui-Lobera. Iron deficiency and cognitive functions. Neuropsychiatr Dis Treat. 2014; 10: 2087–2095.
Beck, KL. Encyclopedia of Food and Health 1st Ed., Academic Press, 2015.
Kocaoz S, Cirpan R, Degirmencioglu AZ. The prevalence and impacts heavy menstrual bleeding on anemia, fatigue and quality of life in women of reproductive age. Pak J Med Sci. 2019 Mar-Apr; 35(2): 365–370.
Cançado1 RD and Manuel Muñoz M. Intravenous iron therapy: how far have we come? Rev Bras Hematol Hemoter. 2011; 33(6): 461–469.
Milman N, Jønsson L, Dyre P, Pedersen PL, Larsen LG. Ferrous bisglycinate 25 mg iron is as effective as ferrous sulfate 50 mg iron in the prophylaxis of iron deficiency and anemia during pregnancy in a randomized trial. J Perinat Med. 2014 Mar;42(2):197-206.
Olivares M, Pizarro F. Bioavailability of iron bis-glycinate chelate in water. Arch Latinoam Nutr. 2001 Mar;51(1 Suppl 1):22-5.
Stoffel NU, von Siebenthal HK, Moretti D, Zimmermann MB. Oral iron supplementation in iron-deficient women: How much and how often? Molecular Aspects of Medicine 75, 10 2020.
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