How to Know if You’re Getting Enough Iron on a Plant-Based Diet (And How Your Approach Should Change As You Age)
Medically Reviewed by Dr. Joel Kahn, MD — Written by Doug Hay — Published Jan 19th, 2024
"Out of nowhere, I'm overcome with crippling fatigue."
That was the opening line from an email we received from Sarah, a 53-year-old woman from New Hampshire.
Sarah is active — she runs a few 10Ks and half marathons each year — and has been thriving on a whole food plant-based diet for the past four years. But when she wrote us (while waiting on blood results from her doctor), she was desperate for answers.
As we later discovered, Sarah was deficient in iron, an essential metal for all living things. Too little iron can cause issues from your brain to your nails (including the fatigue Sarah was experiencing), but too much can be equally as dangerous.
So let's get to the bottom of why iron is so important, how you can avoid Sarah's situation, and the best plant-based sources to support your long-term health.
What Iron Does (and Why it's Important for Your Health)
The role of iron is rather simple:
It forms hemoglobin, a vital protein found in red blood cells. Hemoglobin's primary function is to carry oxygen from the lungs to the body's tissues and return carbon dioxide from the tissues back to the lungs. A deficiency in hemoglobin often leads to anemia, characterized by symptoms like fatigue, weakness, shortness of breath, and pale skin, as the body's tissues and organs don't receive enough oxygen.
On the flip side, maintaining adequate levels of iron presents a number of benefits, like enhanced energy and vitality, improved focus and memory, stronger immunity, and elevated mood and mental health.
Heme vs. Non-heme Iron, Understanding the Difference
You may have heard the argument from meat eaters that plant-based sources of iron aren't adequate. And while that's not true, there are differences between the two types of dietary iron:
Heme Iron
Heme iron constitutes approximately 40% of the iron in meat, poultry, and fish. Heme iron gets its name because it's bound to a heme group, a component of hemoglobin and myoglobin found in animal muscles. This binding allows it to be highly bioavailable.
While absorbed at a high rate, recent research has highlighted the potential dangers of heme iron. Excessive consumption of heme iron has been linked to certain health risks, including an increased risk of colorectal cancer.
Non-Heme Iron
Non-heme iron, on the other hand, is the form found in plant-based foods like legumes, grains, nuts, seeds, and vegetables. It also accounts for the majority — about 60% — of the iron in animal tissue. The argument against plant-based sources of iron comes from the fact that the absorption rate of non-heme iron is significantly lower.
Should Vegans and Vegetarians Worry About Getting Enough Iron?
With such a low absorption rate of non-heme iron, does that mean plant-based eaters are routinely not getting enough? As always, there's nuance.
The current Recommended Dietary Allowances (RDAs) of iron for omnivorous adults aged 19-50 are:
- 8 mg for men
- 18 mg for women
- 27 mg for women during pregnancy
- 9 mg for women who are lactating
But for plant-based eaters, the RDAs are 1.8 times higher.
Many plant foods like leafy greens are rich in non-heme iron, and there are ways to increase the absorption rate, like consuming vitamin C alongside iron-rich plant foods.
- 14.4 mg for men
- 32.4 mg for women
- 48.6 mg for women during pregnancy
- 16.2 mg for women who are lactating
How do your iron needs change after the age of 50?
Being over 50, Sarah's RDA for iron is less than those listed above. For both 50+ men and women omnivorous, the RDA is 8mg, which means plant-based eaters should get at least 14.4 mg per day. Studies show that as you age, your iron metabolism changes, resulting in higher rates of anemia, especially in the elderly.
How to Increase Iron Absorption from Plant-Based Foods
Here are a few techniques to increase your absorption of iron.
- Incorporate Vitamin C-Rich Foods: Eating foods high in Vitamin C alongside non-heme iron sources can boost iron absorption by converting non-heme iron into a form that's more easily absorbed by the body.
- Sprout or Ferment Your Grains and Legumes: This can reduce the levels of phytates, natural compounds known to impede iron absorption.
- Limit Coffee and Tea During Meals: Consuming these beverages with meals can inhibit iron absorption.
Should You Supplement a Plant-Based Diet With Iron?
Supplements can help some vegetarians, vegans, and plant-based eaters get adequate amounts of iron, but because iron has an upper limit of tolerable intake, it's advisable to consult your healthcare provider before supplementing.
Iron-Rich Plant-Based Foods
- Legumes: Lentils, chickpeas, tofu, black-eyed peas
- Nuts and Seeds: Pumpkin seeds, sesame seeds, cashews, almonds, flaxseed
- Vegetables: Broccoli, brussels sprouts, sweet potatoes, white mushrooms
- Leafy Greens: Spinach, kale, swiss chard, beet greens
- Whole Grains: Quinoa, spelt, oats
5 Plant-Based Recipes Rich in Iron
Sarah Reversed Her Anemia — You Can Avoid It Altogether
Maintaining proper levels of iron is essential to a healthy life. Plant-based eaters should ensure they're getting the recommended amount and periodically get blood tests to monitor their body's ability to absorb iron.
