If you’ve noticed you’ve recently felt lightheaded during workouts, struggled with brain fog, or have been more fatigued than usual—even when your daily routine hasn’t changed—it could be worth paying attention to your iron levels.

Iron deficiency is extremely common, and women are disproportionately affected, as we lose a significant amount of blood during menstrual cycles and require more iron during pregnancy and childbirth, per a 2024 review in Blood Reviews. And if you follow a plant-forward diet and/or do endurance training, you’re even more likely to be iron-deficient.

Meet the experts: Taylor Hess, DO, is a neurologist and MS Specialist at the Michigan Institute for Neurological Disorders (MIND). Jennifer Pallian, RD, is a registered dietitian and founder of Foodess.

Iron has a lot of jobs, so it’s important that your body gets enough of it: Not only does it transport and store oxygen for cells and tissues, convert nutrients into energy, and support immune health, but it also helps your brain function. Iron assists your body with producing energy in the brain, supports the protective coating around nerve fibers so signals can travel efficiently, and plays a role in making the chemical messengers that allow brain cells to communicate, says Taylor Hess, DO, a neurologist and MS Specialist at the Michigan Institute for Neurological Disorders (MIND). So, an iron deficiency can lead to some not-so-pleasant symptoms. (More on that in a sec!)

Ahead, learn more about how an iron deficiency can affect your brain function, and what to do if you need more iron, according to experts.

The Link Between Iron and Your Brain

Iron helps produce neurotransmitters like dopamine, serotonin, and norepinephrine, which regulate your mood and motivation, according to a 2021 paper in EJHaem. So when your levels dip, you might feel more irritable, anxious, and fatigued than usual, and you might experience poor sleep, says Dr. Hess.

Low iron can also affect executive functioning—your brain's management system of skills that help you plan, focus, and juggle tasks—due to how iron can interact with dopamine. In fact, low iron has also been linked to reduced attention, slower processing speed, and trouble remembering new information.

“Patients often describe this as brain fog, mental fatigue, or feeling less sharp at work or in conversations,” says Dr. Hess. So, maybe you sit down to answer an email and you’ve reread the same sentence several times without actually processing it, start a few chores but struggle to finish any of them, or walk into a room and completely forget why you went there in the first place.

“In the short-term, low iron can make your brain feel less efficient,” says Dr. Hess, noting that symptoms such as fatigue, brain fog, and trouble concentrating are often reversible once levels are restored. However, the jury is still out on how low iron affects your brain's health and functioning over time.

What to Do if You Think You Have an Iron Deficiency

Traditionally, you may get your hemoglobin levels measured as part of a routine complete blood count when you get your bloodwork—which reflects the iron in red blood cells that carry oxygen. But you’ll also want your levels of ferritin, which demonstrate the body’s iron stores, tested as well. Those stores can start to drop and show low iron in bloodwork before hemoglobin levels change and anemia develops. However, a hemoglobin test alone can miss early iron deficiency.

Hess says that you should especially advocate for ferritin testing if you:

  • Experience persistent fatigue, brain fog, difficulty concentrating, hair shedding, or mood changes that are not otherwise explained
  • Have heavy periods
  • Are pregnant or postpartum
  • Follow a low-iron diet

If ferritin levels come back within a normal range but you’re still experiencing symptoms, it’s important to follow up with your doctor to explore other possible causes.

How to Get More Iron

Daily iron needs vary by age and life stage, but women ages 19 to 50 generally need 18 milligrams per day, while those 51 and over should try to get 8 mg each day to support both physical energy and brain function, per the National Institutes of Health (NIH).

Pallian recommends a food-first approach through heme iron sources like red meat, poultry, fish, seafood, legumes, greens, nuts, seeds, and whole grains. They’re more bioavailable, or easily absorbed and used by the body, compared to non-heme sources, like plant-based foods. (For reference, 3.5 ounces of roast beef tenderloin contains 3 mg of iron, 3.5 ounces of light canned tuna contains 1.67 mg, and one braised chicken drumstick contains 0.89 mg, per the USDA.)

If you choose non-heme sources, pair them with citrus or tomato-based foods to boost the amount of iron you absorb from them. “Nutrients such as vitamin C and carotenoids can enhance absorption by helping convert iron into a more absorbable form,” Pallian says. Additionally, try not to consume iron at the same time foods with substances that can reduce iron absorption. “Coffee, tea, chocolate, and dairy products are best consumed separately from iron-rich meals,” says Pallian.

The timing around when you consume iron can also affect how much you absorb because of the way it works with hepcidin, a liver-produced hormone that helps regulate how much iron the body absorbs and releases. Absorption is “potentially more effective in the morning when hepcidin levels are lower,” Pallian adds.

However, it can be difficult to get enough iron through your diet alone, so you may also consider taking an iron supplement. Just chat with your doctor about your dosage to avoid side effects like constipation and diarrhea.

So, when in doubt, get your iron levels checked. That way, your doctor can help you come up with a comprehensive care plan and you’ll be on your way to feeling like yourself again.