High Iron Content of Spinach – More Than a Myth?
The myth that the superfood spinach contains exceptionally high amounts of iron was debunked by scientists a long time ago. Nevertheless, this green leafy vegetable promoted by the fictional character Popeye has managed to maintain its reputation as an excellent source of iron, perhaps because it actually does contain surprisingly high amounts of iron compared with other vegetables. The problem, however, is that the iron from plant-based foods, including spinach, is not absorbed as well as iron from meat and poultry. Keep reading to get the full story.
How Much Iron Does Spinach Really Contain?
For years, people have been eating spinach, both raw and cooked, in an attempt to step up their iron intakes. The idea that spinach is an iron-rich food dates back to the late 1800s when German chemists first measured the iron content of spinach. Since then, also numerous other scientists have measured the iron content of spinach, but the results of the modern studies have disproved the claims of the German chemists. Today, we know that the claim that raw or cooked spinach contains extremely high levels of iron is simply a persistent myth, based on old and erroneous data (dried spinach is a different story). That, however, does not mean that spinach is a poor source of iron. In fact, a comparison of the iron content of common vegetables reveals that raw spinach contains a fairly good amount of dietary iron.
The following table shows the approximate iron content of common vegetables per 100 grams (3.5 ounces), based on USDA's nutrient data:
- Dandelion greens: 3.1 mg
- Spinach: 2.7 mg
- Asparagus: 2.1 mg
- Swiss chard: 1.8 mg
- Garlic: 1.7 mg
- Kale: 1.5
- Arugula: 1.5 mg
- Brussels sprouts: 1.4 mg
- Garden cress: 1.3 mg
- Artichokes: 1.3 mg
- Chicory root: 0.8 mg
- New Zealand spinach*: 0.8 mg
- Bok choy: 0.8 mg
- Beetroot: 0.8 mg
- Burdock root: 0.8 mg
- Cauliflower: 0.4 mg
- Broccoli: 0.7 mg
- Parsnips: 0.6 mg
- Collards: 0.5 mg
- Cabbage: 0.5 mg
- Cauliflower: 0.4 mg
- Iceberg lettuce: 0.4 mg
- Kohlrabi: 0.4 mg
- Chinese cabbage: 0.3 mg
- Carrots: 0.3 mg
- Cucumber: 0.3 mg
- Tomatoes: 0.3 mg
- Onions: 0.2 mg
*Note: Despite its name, New Zealand spinach (Tetragonia tetragonioides) is not closely related to common spinach (Spinacia oleracea).
Iron Absorption from Spinach
As shown above, 100-gram serving of fresh, uncooked spinach has about 2.7 milligrams of iron, which is equivalent to 15% of the Reference Daily Value for iron. But there's a catch: the iron in spinach (and other vegetables) is so-called non-heme iron, which is not absorbed as well as the heme iron found in animal-based products.
Furthermore, spinach contains oxalates, compounds that have been shown to hinder the absorption of iron in the intestines. On the positive side, spinach contains molybdenum, a trace element that may help your body utilize iron more effectively, and vitamin C, a nutrient that has been shown to enhance non-heme iron absorption.
How to Maximize Bioavailability of Iron from Leafy Greens
As mentioned above, vitamin C makes the iron in plant-based foods, such as spinach, more available to your body's cells. A great way to supply your body with tons of (plant-based) iron and vitamin C is to enjoy a green smoothie featuring fresh spinach and vitamin C rich fruits such as oranges or kiwis (such as this spinach-based smoothie).
Another way to increase iron absorption from spinach is to avoid drinking coffee or tea along with your spinach-containing meal, as the polyphenols in these drinks are known inhibitors of iron absorption. Also foods that contain phytic acids, such as grains and legumes, may reduce iron absorption from foods.
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