For optimal performance and health, women in particular need to make sure their diets include enough iron.
When it comes to nutrition, there’s a lot to think about, from making sure you’re getting enough protein, to incorporating lots of fruits and vegetables. But have you considered how much iron you’re getting from your diet? For active women, it’s a crucial question.
Due to biological factors such as menstruation and pregnancy, women are more likely to struggle with iron deficiency than men. And research suggests that women who exercise or play sports may need to pay even closer attention to their iron levels.
According to a review published by the Journal of the International Society of Sports Nutrition, female athletes may experience “increased iron losses associated with haemolysis (the breakdown of red blood cells), sweating, gastrointestinal bleeding, and exercise-induced acute inflammation.” Just how much you lose is, in part, related to exercise frequency and intensity.
It doesn’t just affect elite athletes, though. One of the referenced studies compared the iron levels of inactive women with women who identified as “habitual runners” (not Olympians, triathletes, or ultramarathoners). The average, everyday runners were found to have significantly lower iron stores than the inactive women.
It sounds grim, but don’t throw in the towel just yet. The benefits of exercise far outweigh the risks, even for people with low iron, says Stacy Sims, PhD, female physiology expert and Tonal Advisory Board member.
“When you’re physically active, you are increasing the cell turnover; you’re increasing your red cell count. You’re also improving your blood volume. You’re improving all the metrics of cardiovascular health that also increase oxygen delivery,” she says.
So, if you’re on the low end of iron normalcy, you should be exercising as part of your overall strategy for boosting your levels. While iron deficiency is a serious health issue that can take a toll on your daily life and hinder athletic performance, it’s generally easy to remedy and prevent. Here’s what you need to know.
Why Is Iron Important?
Found in both animal- and plant-based food sources, iron is a mineral that’s critical to blood health. The body uses it to create hemoglobin, a protein in red blood cells that transports oxygen from the lungs to the body’s tissues and organs, and myoglobin, a muscle protein that stores and carries oxygen. Over time, iron deficiency can develop into anemia, a condition in which the body lacks adequate or properly functioning red blood cells.
“Progressive, untreated anemia results in cardiovascular and respiratory changes that can eventually lead to arrhythmia (irregular heartbeat), an enlarged heart, and heart failure,” says Danielle Gaffen, MS, RDN, LD, founder of Eat Well Crohn’s Colitis. But you’ll likely feel the effects of low iron well before that happens.
What Are Some Iron Deficiency Symptoms?
“Symptoms I frequently see in my private practice clients with low iron levels are fatigue, weakness, decreased exercise tolerance, and difficulty maintaining body temperature,” Gaffen says. Other telltale signs include pale skin, brittle or spoon-shaped fingernails, dizziness, headache, glossitis (an inflamed tongue), lack of appetite, and pagophagia (a craving to chew on ice).
And if you’re planning to compete (even against yourself), don’t expect to set any new records. According to Gaffen, low iron—even a partial depletion of the body’s stores—is a significant “limiting factor” in an athlete’s performance. Oxygen, which relies upon iron for transport and storage, fuels the mitochondria, the “powerhouses of our body’s cells,” she says. Without adequate iron stores, you lose aerobic endurance and the capacity to train. In other words, every workout feels like a drag.
What Causes Iron Deficiency in Athletes?
Sims explains that post-workout inflammation is one of the biggest culprits when it comes to iron deficiency.
“When you’re doing a lot of activity, you tend to have post-exercise inflammation. The intestines are inflamed because they have had low oxygen and low blood flow during exercise,” she says. “And when you have an increase in inflammation, you also have a rise in the hormone called hepcidin, which inhibits the gut’s ability to absorb iron.”
Gastrointestinal bleeding can also play a role in iron loss. During exercise, the protective mucosal lining of the intestines degrades, increasing gastric distress and gastrointestinal bleeding. The mucosal lining eventually regenerates, but it takes about 24 hours. So, if you’re working out twice a day or habitually following up evening workouts with morning sweat sessions, you may have a lower level of mucosal lining. And if you’re a woman, your mucosal lining is already slightly more vulnerable, says Sims.
“Women are more predisposed to GI issues, and a lot of that has to do with estrogen’s relationship to the mucosal lining as well as creatine concentration within the mucosal lining,” she says. “Women have around 70 percent of the stores that men do, so the mucosal lining degrades a lot faster.”
Then there’s the factor of iron consumption.
“A lot of active women and female athletes are very careful about what they eat, and they end up not eating enough iron to support their active lifestyle,” Sims says. They might, for example, swap out red meat and fortified grains—both good sources of iron—for less calorically-dense foods.
How Do You Increase Your Iron Levels?
Fortunately, you’re in control of the main determinant of your iron levels: your diet.
According to the Recommended Dietary Allowances (RDA) for iron, pre-menopausal women should consume 18 milligrams of iron a day. Menopausal women should aim for 8 milligrams.
If you do happen to dip below the normal range (this can be assessed with basic blood work), you’ll want to increase and diversify your intake of iron-rich foods such as beef, beans, dark leafy vegetables, fortified whole-grain bread, and liver. Also important? Everything else you consume with those sources of iron as certain foods can either inhibit or enhance the body’s ability to absorb it.
Iron comes in two forms: heme and non-heme. “Heme iron, approximately 15 percent of which is absorbable, is the organic form in meat, fish, and poultry. Non-heme iron, which can be found in eggs, grains, vegetables, and fruits, has an absorption rate between 3 percent and 8 percent,” Gaffen says.
However, you can bolster the relatively low absorption rates of non-heme sources by pairing them with meat, fish, and poultry. Foods high in vitamin C (think: oranges and bell peppers) also boost the absorbability of both types. So the next time you prepare a spinach salad, top it with some grilled chicken and a squeeze of citrus.
Just don’t pair it with coffee. When consumed with an iron-rich meal, coffee and tea have been shown to reduce iron absorption by 39 percent and 64 percent, respectively. According to Gaffen, vegetable fiber and compounds in foods such as unleavened bread, unrefined cereals, and soybeans can also inhibit iron absorption to varying degrees. There’s no need to eliminate these foods from your diet, as they have nutritional value. Just balance them out with plenty of other iron-rich and absorption-enhancing foods.
Should You Take Iron Supplements?
In general, it’s usually best to aim to satisfy your iron needs through a healthy and balanced diet, but for some, food alone won’t cut it. Before taking any supplements, consult a doctor for approval and guidance on dosage. Once you get the okay to take supplemental iron, stick to ferrous iron because it’s more bioavailable than ferric iron. And, if you get a monthly period, Sims recommends taking iron on the first day of bleeding and then every other day until ovulation.
“If you take [an iron supplement] every day, that can increase hepcidin [the hormone that inhibits iron absorption]. If you have too much iron, then the body’s like, ‘I don’t need it,’” she says.
You may also consider supplementing with vitamin D, especially if you don’t spend much time in the sun.
“Vitamin D is super important for downregulating hepcidin,” Sims says. “So, we tell women to take vitamin D around training. That helps with that inflammatory response and reduces hepcidin. That’s another key link for people trying to increase their intake and absorption of iron.”