How healthy are green smoothies?
If you don't like eating your vegetables, join the growing number of those who are drinking them instead.
Slurping smoothies made with raw, leafy green vegetables has become more popular as books and blogs about this trend sprout up.
Green smoothies are good sources of minerals and vitamins. Still, people who have diabetes or kidney stones should be careful about what they mix in, experts say.
Consuming green smoothies is a good way to get vegetables in your diet, says Joan Salge Blake, a spokeswoman for the Academy of Nutrition and Dietetics. Vegetables are high in potassium, "which can help lower blood pressure," and if they're pureed, "so the fiber is still intact, they'll help fill you up."
"Having smoothies is a way to stay hydrated," she adds.
Sergei Boutenko of Ashland, Ore., says he's been consuming green smoothies for almost 10 years and drinks at least a quart every day. He mixes fresh, organic green vegetables and fruits with water in a blender. He also includes edible wild plants.
Boutenko, 28, a videographer and writer, says such smoothies boost his energy, help his digestion and improve his muscle recovery after workouts. He's working on a documentary, Powered by Green Smoothies, about how endurance athletes perform when given green smoothies. It will premiere in February.
Boutenko says he rotates the greens in his smoothies to avoid a buildup of alkaloids, compounds that can cause mild but unpleasant symptoms such as stomachaches. He chooses vegetables that are in season.
Green smoothies also have raised concerns about oxalates, which form oxalic acid, linked to kidney stones. Oxalates are common in greens such as raw spinach and Swiss chard. They can be broken down to varying degrees by different cooking methods.
People who are at risk of calcium oxalate stones, a type of kidney stone, may need to monitor oxalates in their diet, says Blake, clinical associate professor of nutrition at Boston University. Talk to your doctor if you have a family history, she says.
Blake urges caution when using cream or other ingredients that can add fat and calories to smoothies. Also, fruits and juices contain carbohydrates, she says. "Individuals with diabetes need to monitor their total carbohydrate consumption."
Kristi Crowe, spokeswoman for the Institute of Food Technologists, a Chicago-based science society, says spinach is one of the great green vegetables to use in smoothies. Celery, kale, beet leaves, cucumbers and parsley are other good options. Those vegetables blend well with green apples and kiwi, says Crowe, an assistant professor of nutrition at the University of Alabama. "Also, carrots and beets add a boost of nutrients."
Crowe encourages using more vegetables in smoothies than fruits; veggies have abundant antioxidants and less sugar than fruits, she says.
In general, experimenters can get creative -- there are no combinations of fruits and vegetables that should be avoided, she says. Yet some veggies have overpowering tastes: "If it's strong in flavor, then use less of it."
Go slowly when adding protein powders, she adds; they can cause clumping and uneven texture. She suggests trying Greek yogurt, which also has lots of protein, instead.