Spinach has long been associated with Popeye the Sailor’s superhuman strength. The cartoon character used to gulp down cans of spinach as if his life depended on it, and the message that got passed on to the children of the time was that spinach was a superfood that could make them as strong as their favorite hero. One of the pieces of information that got added to this narrative about spinach was the idea that it contained a lot of iron. In reality, while spinach is undoubtedly a nutrient-dense leafy green with many health benefits, the iron it contains is not as abundant as people have been led to think.
The Roots of the Myth
The myth about spinach and iron was born out of a misunderstanding. Back in 1870, a German chemist named Erich von Wolf published a paper on the iron content of various vegetables. By mistake, he misplaced a decimal point, thus overestimating the iron content of spinach tenfold. While von Wolf corrected his mistake in a later paper, the flawed data had already made its way into the public consciousness. Over time, other factors helped perpetuate the spinach myth. For one, spinach’s high vitamin C content can facilitate the absorption of non-heme iron (i.e., iron from plant sources), but this effect is not as significant as the myth suggests. Moreover, the United States Department of Agriculture (USDA) used to list spinach as one of the top iron-rich foods in its database of nutrient values, which only reinforced the perception of spinach as a high-iron food.
The Reality of Spinach’s Iron Content
In reality, while spinach does contain iron, the amount is not as impressive as many people think. According to the USDA, one cup of cooked spinach (which is about one-fourth of the usual serving) provides about 6% of the daily value (DV) of iron for adult men and women. In comparison, a serving of boiled beef liver provides 54% of the DV, while a serving of canned clams has 236% of the DV. Generally, animal-based foods are richer in heme iron, a type of iron that is more easily absorbed by the body. Plant-based foods like spinach contain non-heme iron, which is less well-absorbed because of its chemical structure. Some other leafy greens actually have more iron than spinach, such as swiss chard, kale, and beet greens.
Spinach’s Other Health Benefits
Even if spinach does not have as much iron as its reputation suggests, it is still an excellent source of many other nutrients that promote health. For example, spinach is packed with vitamins A, C, and K, as well as folate and fiber. Additionally, spinach has several phytonutrients that have antioxidant and anti-inflammatory properties, such as lutein, zeaxanthin, and flavonoids like quercetin and kaempferol. These compounds may help protect against cancer, heart disease, and other chronic conditions. Some studies have also suggested that spinach can improve glycemic control, lower blood pressure, and enhance bone health.
While the myth about spinach’s iron content may have led to some disappointment for those looking to increase their iron intake, spinach remains a nutrient-dense food with many health benefits. Spinach may not be the best source of iron, but it certainly has plenty of other nutrients that make it worth adding to your diet. The good news is that there are many other foods (and supplements, if necessary) that can provide the iron you need, especially if you are at risk of iron deficiency.
- Hamblin, J. (2020). Don’t Blame Popeye for Spinach’s Reputation. The Atlantic.
- USDA. (2021). Spinach, Cooked, Boiled, Drained, Without Salt. National Nutrient Database for Standard Reference Legacy Release.