Call me Popeye (or maybe Popette?), because I’m absolutely obsessed with spinach. I eat it constantly, cooked and raw, in everything from nachos to pasta to salads to hummus. The other day, I tweeted about my deep, abiding love for the leafy green and one of my friends replied to my tweet, saying that eating large amounts of spinach can actually interfere with the body’s ability to absorb calcium. Wait, what? This was news to me, as I always thought spinach was hands-down one of the healthiest foods you could eat. Confused, I did a little research, hoping my love for my favorite vegetable wasn’t actually harming my health. I didn’t find much information, so I took my question to the experts. Here’s what they had to say about the science of spinach and calcium absorption.
Registered dietitianÂ Mary HartleyÂ explained that oxalate, a pesky little molecule that binds to the calcium in spinach, leaves only 10% of the essential mineral available for absorption:
Oxalate occurs naturally in many common plants, especiallyÂ rhubarb andÂ dark leafy greens such as spinach, chard, beet greens, and kale. It’s present in lesser amounts in other vegetables, fruits and nuts. Oxalate binds with calcium in the digestive tract to formÂ anÂ insolubleÂ saltÂ that cannot be absorbed. For instance, one would have to eat 15.5 cups of raw spinach to match the level of calcium absorbed from one cup of milk. Oxalates do not significantly impact calcium absorption except when levels are high. Still, it is important to remember that dark leafy greens are not an important source of calcium in the diet.
Uh oh. Bad news forÂ vegans who rely on leafy greensÂ as a large source of calcium.
Dr. Bess Stillman, integrative medicine consultant and practicing ER physician in New York City, told me more about spinach specifically, and its role in a healthy diet:
In addition to the vast array of cancer fightingÂ anti-oxidants and flavanoids, research has shown that a compound calledÂ ”glycoglycerolipids,” found in the spinach leaf, can prevent damage andÂ inflammation to the lining of the stomachâ€”meaning a healthier digestiveÂ tract that’s better at absorbing the nutrients you need to feel energized andÂ healthy.Â Spinach also is a fantastic source of iron, making it an especiallyÂ important food for both vegetarians and women, who often need iron to helpÂ replace blood lost during their monthly periods.
Whew. No need to panic (or cut spinach out of your diet). Dr. Stillman comments that, “in the case of spinach, it’s all about how you eat it.” Here are herÂ suggestions on how you can cook spinach so you can get the maximum nutritional benefits of the little green leaf:
- Cook It:Â Lightly cookingÂ spinach will also breakdown the oxalic acid molecules without causing youÂ to lose too many of the vital nutrientsâ€”try steaming, sauteeing orÂ blanching, which also increases the amount of vitamin K available.Â Pour someÂ extra virgin olive oil into a pan on low to medium head and sautee lightlyÂ until the leaves begin to wilt.
- Eat With Citrus Or Tomatoes:Â The Center forÂ Disease Control and Prevention recommends eating spinach with citrus orÂ tomatoes. These foods are high in vitamin C, which changes the form of ironÂ in spinach to the easily absorbed kind you find in steakâ€“but with muchÂ fewer calories or risks to your health. Vitamin C also blocks the oxalateÂ from binding to calcium, encouraging further absorption. Try adding spinach to your pasta sauce, or make your BLT a bacon spinach tomato sandwich. Toss with orange muscat vinagrette and enjoy absorbing both the flavors and the nutrients you want.
- Buy Organic:Â Remember, spinach is one of the “dirty dozen” foods, which have highÂ pesticide residue. To get the most out of spinach’s health benefits, buyÂ organic.