Spinach – Iron in the Soul?

popeye-spinach-ironPopeye, the popular cartoon character, got it all wrong about spinach.

He ate mounds of spinach, thinking it contained plenty of iron to make him strong. But it turns out that spinach isn’t the best source of iron. Scientists in the 1890’s made a mistake while calculating the nutritional value of various vegetables and put a decimal point in the wrong place. For a long time, people thought that spinach contained ten times more iron than it actually did.

It also isn’t necessarily true that the more iron you eat, the stronger you become. Increasing your intake only makes you feel stronger if you are iron deficient in the first place. Iron is part of haemoglobin, the red pigment in the blood, which carries oxygen to all the cells around the body. Iron-deficiency anaemia results in a decrease in the amount of oxygen the blood is able to carry. Symptoms include unusual fatigue, lack of concentration, dizziness and palpitations. More advanced symptoms can be headaches, a sore or swollen tongue, pale skin, “restless” legs and a desire to eat unusual things (clay, cardboard).

A lack of iron may be due dietary deficiencies or conditions that cause blood loss such as heavy menstruation, piles, ulcers or gastrointestinal bleeding. Pregnant women, people with gluten intolerance, children or adolescents during a growth spurt, or those who simply don’t produce enough gastric acid for proper digestion may be at risk of iron deficiency. It’s important to get a proper medical diagnosis and to be aware that there could be many different reasons for fatigue, not just iron deficiency. For example the body also requires vitamin B12 and folic acid to produce red blood cells. If there is a lack of any of these, anaemia will develop.

The most absorbable form is called “heme” iron and is found in red meat, eggs, the dark meat of chicken and turkey and oily fish like sardines. “Non-heme” iron is less well absorbed and found in fortified cereals, beans, nuts, seeds, dried fruit and dark green vegetables like spinach. Vegetarians who don’t replace meat with iron-rich foods may be low in the mineral.

Only use supplements if you have been diagnosed with iron deficiency as taking iron supplements can be harmful. The reason is that iron cannot be excreted by the body and must be either used up or stored. Excess storage promotes bacterial infections because bacteria require iron for growth. Iron supplementation can also interfere with the absorption of other minerals such as zinc which is needed for a healthy immune system. Supplementing a zinc-deficient person with iron may weaken their immunity whilst stimulating bacterial growth.

Those who are at risk of iron deficiency should avoid drinking wine, tea and coffee – these contain tannins which block the uptake of iron. Vitamin C, on the other hand, increases the absorption of iron and some supplements include vitamin C to encourage its uptake. Nutritionists can advise on suitable brands that are easier to absorb and lessen the risk of common side-effects of iron supplementation such as constipation and stomach irritation.

© 2011 Martina Watts MSc Nut Med, first published Brighton Argus October 2003


  1. says

    Great article. I was once a believer in eating spinach for all my iron needs (Popeye aside) but I’ve read now that it may not be the best source of the nutrient. I’m curious about your caution on supplementation, especially the part of only supplementing if a deficiency exists. I thought supplementation particularly for endurance athletes wouldn’t be ill advised. Would you mind expounding on that further? Would supplementing with a multi-vitamin carry the same risks? Thanks.

    • Martina Watts says

      Hi Maximilian,

      Supplementation can be a mine-field but can have its place! Some people supplement with single nutrients (in my opinion never a good idea especially if long-term), some people use super high doses (also questionable if long-term and synthetic), some use poor quality multis (with added sweeteners, binders or fillers) and so on. The other problem I often encounter is that many people have digestive issues that make absorption of supplements (especially in tablet form) tricky. So that’s why Nutritional Therapists exist – we are trained to assess each person individually according to their diet/lifestyle/medical history/digestion/goals. My short answer to your question: a multi for an endurance athlete is probably a good idea (if it is of high quality) but so would be a look at his/her diet in general, as well as digestive capacity. Our assessments include thorough case history taking/questionnaires as well as lab testing if necessary. Hope this helps!

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