Philip J. Goscienski, M.D.
August 2011
Sorry, Popeye, it's not the iron. Thanks to a cartoon character, three generations of mothers have foisted spinach on their kids in the belief that this you-have-to-learn-how-to-like-it leafy green plant food is rich in iron. Compared to other vegetables, spinach does have a moderately high iron content. Unfortunately, most of it doesn't get taken up in the course of digestion. Early nutritionists were not aware of the fact that some plant foods contain an ingredient that binds so tightly to the iron that it never gets absorbed.
The villain is oxalate, which is present in many fruits and vegetables. The highest amounts are present in beets, spinach, Swiss chard and rhubarb, none of which is found with great frequency on any home or restaurant menu. You may have heard that there is some oxalate in chocolate but the ounce or two that most people consume in one sitting is of no consequence. When oxalate is absorbed into the bloodstream it can form a complex with calcium. A regular high intake of oxalate-rich foods can lead to the formation of kidney stones. A couple of servings of spinach per week don't pose a risk for those who enjoy it but persons with a history of calcium oxalate stones should have it only occasionally.
Although the value of iron in spinach has been exaggerated, its other nutritional benefits are well deserved. Like most highly-colored plant foods, spinach is rich in antioxidants and it has high levels of vitamin A, Vitamin C and folate. Spinach also has a considerable amount of vitamin K, which is a healthy nutrient but it can affect the clotting tendency of persons who are taking prescription blood-thinners.
Spinach is an excellent substitute for iceberg lettuce in salads and sandwiches. Iceberg lettuce has a pleasant mouth feel but not a lot of nutritional value. It does have some vitamin A but not nearly as much as spinach does and much less of the other vitamins. Spinach has about 50 percent more fiber than iceberg lettuce.
A generation ago, Mom wasn't too happy about having to rinse the leaves over and over to get the sand out. Modern technology has brought us baby spinach, prewashed, conveniently bagged and no sand. If you're concerned about the one outbreak of E. coli disease that was linked to spinach in 2006, serve it cooked.
Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.