Reviewed by Edward C. Geehr, M.D., Lifescript Chief Medical Officer
You just stumbled out of yoga class. You’re hot, sweaty and need a pick-me-up. Go for a nonfat latte? No, you grab a kale juice instead. Juice is now the beverage of choice for people on the go. Harried moms drink it. So do yoga fans. Celebrities Gwyneth Paltrow, Jared Leto and Salma Hayek do too. They’re juicing – chugging raw fruit-and-vegetable drinks to “cleanse” their bodies, get a speedy meal, consume more produce or lose weight.
Juice is the new latte. About 92 million gallons of super-premium juices were consumed in 2013, up from 71 million gallons in 2007, according to Beverage Marketing Corp., an industry research firm. No wonder! Juice is an easy way to get fresh vegetables and fruit. It makes for a fast breakfast or lunch, and it’s healthful.
Or is it? Could something this good be bad for you?
Yes, especially if you have a chronic condition or are taking certain drugs, says Adrienne Youdim, M.D., assistant professor of medicine and medical director of the Center for Weight Loss at Cedars-Sinai Medical Center in Los Angeles.
Even if you’re a healthy person, too much juice can be dangerous, warns nutrition expert Carol Koprowski, Ph.D., R.D., assistant professor of clinical preventive medicine at Keck School of Medicine of USC in Los Angeles.
So before grabbing a carrot juice instead of lunch or spending hundreds on a cleanse, read on for the ways juicing can hurt you.
1. You could risk dangerous drug interactions.
The high vitamin K content in a spinach-kale smoothie, for example, can be life-threatening if you take blood-thinning medications, like warfarin. Such anticoagulants often are prescribed after a stroke, deep vein thrombosis or other circulatory conditions.
Kale, spinach, turnip greens, collards, Swiss chard, parsley and mustard greens – green juicers’ favorites – contain up to 550 micrograms of vitamin K per cup, which can lower the drugs’ anti-clotting activity. If you take anticoagulants, you should only eat a half-cup of leafy greens a day, according to the National Institutes of Health Clinical Center. Eat the same amount every day too, because big changes in vitamin K intake could lead to a blood clot, and a stroke or death.
If you’re one of the 70 million people taking cholesterol-lowering statins, stay away from grapefruit juice. The citrus fruit blocks an intestinal enzyme that controls absorption of drugs such as simvastatin or atorvastatin. You’ll also face a higher risk of muscle and joint pain, muscle breakdown, liver damage and kidney failure if you drink grapefruit juice (or eat the fruit) while taking statins, according to the Cleveland Clinic. Grapefruit also can interfere with drugs for high blood pressure, anxiety, allergies and other ailments, according to the Food and Drug Administration. So ask your doctor if your prescriptions may interact with the fruit.
2. You could develop diabetes.
About 79 million Americans have prediabetes, according to the American Diabetes Association. That means they have blood sugar readings that are higher than healthy but not yet high enough for a diabetes diagnosis. Juicing could tip those at risk over the edge, according to a 2010 Harvard University study of 187,000 nurses.
Drinking one or more daily servings of apple, orange, grapefruit and other juices increases the risk of developing type 2 diabetes by 21%, the study found. If you have the metabolic disorder, juicing could lead to blood sugar spikes because you’re getting all the sugar of fruit without the fiber, Koprowski explains. The fiber in whole fruit and vegetables slows the absorption of sugar into the bloodstream.
If you’ve been told you have prediabetes, eat the whole fruit instead. But limit daily intake to one small piece of fruit or one cup of fresh berries or melon, Koprowski advises.
3. You could damage your kidneys.
Beware of fruit and vegetable juices with high amounts of potassium, such as bananas and kale, if you have kidney problems. Four-and-a-half cups of chopped kale – the amount in 8 ounces of juice for a “cleanse” – can be lethal if your kidneys are weak because of high blood pressure, severe infection, an enlarged prostate, certain drugs or pregnancy complications.
Even most lower-potassium foods are off-limits to people with kidney problems because the amounts add up quickly. Adults need 4,700 mg of potassium daily to keep the heart and muscles working. In healthy people, the kidneys generally excrete the excess. But that doesn’t happen in people with compromised kidneys: Potassium builds in their blood, raising the risk of a heart attack and stroke, according to the National Kidney Foundation. They should limit their intake of potassium to 1,500 -2,000 mg per day.
If you have experienced weakness, numbness or tingling – signs of potassium overload – call your doctor immediately, advises Judy D. Simon, M.S., R.D., a clinical dietitian and nutritionist at the University of Washington Medical Center’s Roosevelt Clinic in Seattle.
4. You could threaten your thyroid gland.
Kale, bok choy, cauliflower, collards and spinach are rich in glucosinolates, which form goitrin, a compound associated with hypothyroidism or insufficient thyroid hormone. High amounts of these veggies have caused hypothyroidism in animals, according to Oregon State University’s Linus Pauling Institute. One 88-year-old woman lapsed into a coma after eating 3 pounds (or 2 cups of juice) per day of raw bok choy for several months, according to the institute. But researchers aren’t sure if her condition was caused by the bok choy or another problem, such as an autoimmune disease.
The National Cancer Institute recommends eating a variety of vegetables daily – not just leafy green ones. The CDC’s fruit-and-veggie calculator helps you determine how much you need. But there are no separate intake recommendations for people with hypothyroidism, so talk to your doctor before juicing.
5. You might get food poisoning.
One reason fresh juice is healthful is that it’s unpasteurized, so the taste and nutrients are preserved. But when juices aren’t heated to 154° F for 30 minutes to kill germs, they’re more vulnerable to lethal bacteria, such as salmonella, Listeria monocytogenes and Toxoplasma gondii, according to the Centers for Disease Control and Prevention (CDC).
Even if it’s bacteria-free during manufacturing, fresh juice sold in stores may be contaminated after it leaves the plant – for example, in shipping, storage or in your home. If you leave a container of juice on a table overnight, toss it. Otherwise you risk food poisoning and major intestinal problems, the U.S. Department of Agriculture warns.
Most store-bought, bottled fresh juices last up to 3 days if refrigerated and unopened, Koprowski says. Drink them within a day once you’ve opened the seal. Flash-pasteurizing – heating juice at 160° for 15-30 seconds – offers a longer shelf life, about 3 weeks in the fridge, while preserving some nutrients. Companies such as Naked Juice and Odwalla treat their juices this way. Products that aren’t pasteurized must say so on the package.
6. Juice cleanses don’t work.
We clean out our houses and cars. So why not our bodies? That’s the reasoning behind juice cleanses, which are intended to rid your body of toxins. Forget about it. The practice is a waste of time and money, because your body doesn’t need “cleansing,” says Dr. Youdim of Cedars-Sinai. “Our bodies have their own elaborate, elegant detoxification system, called the liver, intestines and kidneys,” she explains. “It’s foolish to think the body can’t detox on its own,” she adds.
7. Juices can be calorie bombs.
If you’re downing up to 96 ounces of juice a day to lose weight – which many fasts recommend – stop, USC’s Koprowski warns. Juicing for days to lose weight “can be potentially harmful,” she says. That’s because you’re losing out on important nutrients. And don’t expect to get slimmer, says Dr. Youdim. In fact, you might gain weight, because you’re consuming more calories than you realize – mostly from naturally occurring sugar in the fruits and vegetables.
Some juices and smoothies are more caloric than a meal. For example, a large Jamba Juice Razzmatazz Smoothie, made with mixed berry juice, orange sherbet, strawberries and bananas, rings up at 580 calories. Consume too many, and “you can end up with a few thousand calories of juice a day!” Simon warns.
And still be unsatisfied. “It can take 10-15 oranges or several pounds of carrots to make a meal of juice,” Koprowski says. “Or you could munch on a couple of carrots and feel full.”
8. You’re passing on protein.
Eight ounces of kale juice is packed with vitamins A (3,500% of your daily recommended amount), K (4,300%) and C (1,200%), plus iron, calcium and antioxidants. But you’ll get only about 2 to 8 grams of protein. That’s not enough if you’re drinking juice as a meal replacement. A 130-pound woman needs 65 grams of protein daily to repair cells and create new ones.
Protein also preserves and builds lean body mass, which helps keep you healthy and even burns calories, Dr. Youdim explains. “Fruits and vegetables [alone], however, are not a great source,” Koprowski says.
9. You’re forsaking fiber.
Juicing gives you the nutrients of fresh produce – but removes the pulp and fiber – necessary to keep your colon in good working order, reduce heart disease risk, and lower cholesterol and blood sugar levels. “When you drink orange juice, you get vitamin C, but it’s not the same as eating an orange,” Simon says. The whole fruit has the vitamin plus fiber, with far fewer calories than a glass of juice. It’ll also keep you full longer.
10. You’ll pay premium prices.
A daily juice habit is expensive – about $3,500 yearly if you buy one a day from a premium juice bar.
Lifescript checked around at local stores and found that:
- Evolution Fresh costs $2.99 to $6.99 for a 15-ounce bottle at Starbucks.
- You’ll pay $5.99 to $9.99 for the fresh juice bar at Whole Foods.
- Premium juice bars in Los Angeles charge $10 to $15 for 8-ounce refreshers.
The bottom line: Juices are better than a burger and fries, and can be a good addition to your diet – if you’re healthy and consume them in moderation. “But if you want to live a healthy life and prevent chronic diseases without spending a fortune, eat whole vegetables and grains, not ‘detox’ protocols,” Dr. Youdim advises.
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Before anyone begins to fill my message box with comments as to why this article is contrary to your opinion on juicing, please know that I've shared this article because there is far less information online about the potential harms of juicing than there is of the claimed benefits. Take my post today as 'food for thought!'
From Him, Through Him, For Him (Romans 11:36),
Paul J. Staso
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