The Silent Cause of Tiredness

Too often the response to the question “How are you?” is, “Tired.” A list of reasons justifying the fatigue usually follows: working hard and late, a household of children and/or visitors, too many outside commitments with deadlines, school papers and exams, inadequate sleep, recovering from a cold, and, of course, stress. The list could go on. Missing from this list, however, is a silent but potent cause of tiredness: iron deficiency anemia.  Iron is needed by the body to make hemoglobin, the constituent of red blood cells that transports oxygen from the lungs through the blood and delivers it to the cells. If, over a period of time, too little iron is consumed to make hemoglobin in amounts necessary to meet the needs of the body, iron deficiency anemia results.

Extreme fatigue is one of the symptoms of iron deficiency anemia, along with decreased stamina, increased vulnerability to infections, sensitivity to cold, increased heart rate and dizziness. Pale skin is also a symptom, but like so many of these signs, especially fatigue, other reasons for their presence can easily be summoned.  Many of us assume that we are suffering from some yet identified virus if we feel dizzy or out of breath climbing stairs. And, for many people, being pale in the winter is hardly considered unusual. And we often respond to our tiredness by eating. “Maybe if I eat a snack, I will feel more energetic,” we tell ourselves as we reach for a cookie or bag of chips.  We are unlikely to consider that maybe our fatigue is caused by an insufficient amount of iron in our diets. Unnoticed and unchecked, the depletion of iron stores continues to cause persistent fatigue that does not respond to more sleep or getting over a viral infection.

The National Institutes of Health Office of Dietary Supplements recommends that men and women of non-childbearing years obtain 8 mg of iron daily and 18 mg for premenopausal women. The larger requirement for women of childbearing age is based on monthly blood loss from menstruation.  Blood losses from medical conditions may also decrease iron stores. I had a neighbor who had a silent bleeding ulcer for months and was found to be severely anemic.

Iron deficiency anemia is not uncommon.  (“Iron Deficiency Anemia,” Killip S, Bennett J, Chambers M, Am Fam Physician 2007 1: 75: 671-678) According to a recent publication in the American Family Physician, “ The prevalence of iron deficiency anemia is 2 percent in adult men, 9 to 12 percent in non-Hispanic white women, and nearly 20 percent in black and Mexican-American women.” The trend toward intermittent fasting or cleanse diets may increase these numbers as a one or two-day fast cleanse diets, has been shown to rapidly deplete iron. (“Effect of short-term food restriction on iron metabolism relative well-being and depression in healthy women,” Wojciak R, Eat Weight Disord. 2014; 19:21-327)

Obtaining the necessary amount of iron from the diet is not as easy as, for example, getting enough vitamin C.  Although many foods contain iron, not all the iron in the food gets into the body. There are two types of iron: heme iron and non-heme iron. Heme iron comes from animal sources and is considered more “bioavailable” than non-heme iron. This means that the iron in the food is more able to get into the body from the intestinal tract than non-heme iron.

Liver is a good source of heme iron, but this food is not universally enjoyed (except, perhaps, by cats).  Lean meat and seafood, especially octopus, are also good sources, although the latter is also not particularly popular. Indeed, for most non-vegetarians as well as vegetarians and vegans, more of our iron comes from plant sources than animal foods.  According to the Office of Dietary Supplement report, about half of the iron we eat comes from fortified bread, cereal and other grains. In fact, cereal is a good source of iron:  one cup of bran flakes contains 4.5 mg of iron which is about half the amount men and post-menopausal women need each day. An avoidance of grain products means that the vegetarian and vegan eater must depend on obtaining iron from vegetables, lentils, dried beans, soy products like tofu, and nuts and seeds. The amount of iron in plant foods that are not fortified is low so that large quantities must be eaten each day to meet iron intake requirements, especially for women of childbearing age.  Moreover, there often is a misperception of how much iron is in the foods we think of as good sources of this mineral.

“I eat plenty of spinach and nuts,” a friend will say, “so I am not worried about getting enough iron even if I try to avoid eating meat.“  But an entire cup of cooked spinach (which is a large amount raw since it shrinks when cooked) has only 6 mg of iron. A cup of cashew nuts has 4 mg and lots of calories. Two large eggs have less than 2 mg of iron and one would have to eat an entire cup of hummus to get 5 mg of iron.

Iron in plant foods is also less “bioavailable” than the iron in animal foods. There are phytates and other substances in plant foods that grab hold of the iron and prevent much of it from being absorbed into the body from the intestinal tract. In fact, studies on the iron status of vegetarians have shown that they tend to have lower iron stores than non-vegetarians.   (“The effect of vegetarian diets on iron status in adults: A systematic review and meta-analysis,” Haider L, Schwingshackl L2, Hoffmann G3, Ekmekcioglu C ,  Crit Rev Food Sci Nutr. 2018; 58(8):1359-1374)

Fortunately, eating foods that are high in Vitamin C counteracts the effect of phytates on preventing iron from entering the body. Eating a vitamin C-rich food such as citrus fruits or juice, strawberries, broccoli, cauliflower, Brussels sprouts, and peppers including chili peppers, with an iron-containing food like oatmeal or tofu, significantly increases the absorption of iron, especially for people with low iron reserves.

However, if blood tests show that iron deficiency or iron deficiency anemia is present, it may be necessary to take an iron supplement and doing so should be under the care of a physician.  For many, this may be an easier solution than eating chopped liver or grilled octopus.  Once the problem is resolved and iron stores are back to normal, fatigue and the other symptoms of the anemia should disappear.

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