Hold the Kale! 11 Reasons Juicing Can Be Bad for Your Health

You just stumbled out of yoga class. You’re hot and sweaty and need a pick-me-up. A green juice is the logical refresher. While juice cleanses may have seen their celebrity-fueled heyday years ago, the juicing trend is still going strong.

Juicing is, simply, drinking a juice, often with the goal of boosting your health, replacing a meal, or replacing an entire day’s worth of meals. Fresh squeezed juices can include a variety of fruits and vegetables, like greens, beets, carrots, celery, lemon and lime, apple, or pineapple. You can buy them from a juice bar or bottled in the refrigerated section of your grocery store. Alternatively, you can juice your own fruits and veggies at home with a juicer.

Is Juicing Good or Bad Nutritionally?

Just because it comes from a fruit or veggie does not mean that it’s healthy all the time — or totally harmless. Before juicing, you need to be particularly careful if you have a chronic condition or are taking certain drugs, says Adrienne Youdim, MD, an expert in medical weight loss and nutritional therapy in Beverly Hills, California.

Dangers and Side Effects of Juicing to Be Aware Of

It’s important to consider the following things before grabbing a freshly squeezed juice:

1. You Could Risk Dangerous Drug Interactions

It’s easy to assume that a juice is benign, but you may be surprised at how some juices don’t mix with your meds. According to the U.S. Food and Drug Administration (FDA), grapefruit juice, for instance, can interact with certain drugs that lower cholesterol, like atorvastatin (Lipitor); medication that lowers blood pressure, like nifedipine (Eqv-Adalat CC); corticosteroids like budesonide (Pulmicort); and antihistamines like fexofednadine (Allegra). As the FDA explains, grapefruit juice can increase the amount of medication entering the blood, thereby over-enhancing its effects, including side effects.

In addition, as the Cleveland Clinic points out, eating too much vitamin K at one time can counteract blood thinners like warfarin (Coumadin). Such anticoagulants often are prescribed after a stroke, deep vein thrombosis, or other circulatory conditions. Leafy greens (kale, spinach, swiss chard, parsley) are rich sources of vitamin K that are commonly used in green juices.

That said, one study concluded that there’s no evidence to suggest you should forgo vitamin K–rich foods while taking these meds. A better strategy, the authors say, is to keep your intake consistent. For instance, before starting to drink green juice daily, talk to your doctor to see if you’re on the correct dose of medication or if any necessary adjustments need to be made.

2. You May Increase Your Risk for Type 2 Diabetes if You Have Prediabetes

According to the American Diabetes Association, more than 96 million American adults have prediabetes. This is a condition where blood glucose levels are higher than normal but not elevated enough for a type 2 diabetes diagnosis. One study found that upping intake of sugary beverages — which include 100-percent fruit juices — by ½ cup or more per day increased the risk of diabetes by 16 percent. On the other hand, switching out a glass of juice with a naturally calorie-free beverage, like water, black coffee, or tea, decreased that risk by up to 10 percent.

If you’ve been told you have type 2 diabetes, eat whole fruit in moderation instead of drinking juice, advises Carol Koprowski, PhD, RD, assistant professor of clinical research in preventive medicine at the University of Southern California in Los Angeles. Indeed, a study found that while fruit juice was associated with a higher type 2 diabetes risk, whole fruit had the opposite effect on risk, likely because of the fiber contained in whole fruits. (More on this later.) Researchers particularly singled out blueberries, apples, and grapes as having protective effects against diabetes.

For fruit, fresh, frozen, or canned varieties without added sugars are all great options, says the American Diabetes Association. Yet, fresh or frozen fruit are the best choices nutritionally.

RELATED: Is Juicing a Good Idea if You’re Managing Type 2 Diabetes?

3. You Could Damage Your Kidneys if You Have Kidney Disease

Fruits and veggies are naturally rich sources of potassium, which is usually a good thing — the mineral plays a key role in blood pressure regulation, according to the American Heart Association. Your kidneys do the important job of excreting excess potassium. If you have chronic kidney disease (CKD), that function doesn’t work as well, and potassium can build up in your blood. As such, you’ll have to limit your potassium intake, as too much of the mineral can cause dangerous side effects, including an irregular heartbeat or heart attack, according to the National Kidney Foundation (NKF).

If you have CKD, it’s likely you’ll be on a potassium-restricted diet, which will involve limiting your intake to about 2,000 milligrams (mg) per day, says the NKF. You may need to limit high-potassium foods that are often used in juices, like banana, grapefruit juice, avocado, dates, beets, honeydew, kiwi, mango, carrots, orange, leafy greens, pomegranate, prune, and vegetable juice in general.

For anyone who has CKD and has experienced weakness, numbness, or tingling — signs of potassium overload — call your doctor immediately, advises Judy D. Simon, MS, RD, a clinical dietitian at the University of Washington Medical Center in Seattle.

4. You May Face Food Poisoning if Choosing Cold-Pressed Juice

While cold-pressed juice might taste the freshest, it’s not pasteurized, and it may increase the risk of food poisoning, the FDA warns. That’s because juicing allows bacteria on the outside of the produce to become incorporated into the juice. Pasteurization, however, destroys bacteria that can make you sick.

Typically, people with healthy immune systems are fine, but those who are compromised, such as pregnant women, children, and older adults, are at a greater risk.

Signs of foodborne illness include vomiting, diarrhea, cramping, fever, and headache.

Compared with homemade or ready-to-make varieties, prebottled cold-pressed juice poses a bigger risk for food poisoning because microbes have more time to multiply. Yet if you’re making your own juice at home, you still need to take proper food safety measures, including washing your hands and the produce during prep, to reduce the risk of illness, says Kelly Johnston, RDN, a health coach with Parsley Health in New York City.

According to BevSource, flash pasteurization is another way some bottled cold-pressed juices are made. This is when juices are brought to a higher temperature for a shorter amount of time compared with traditional pasteurization. This process can help preserve nutrients without compromising the safety of the juice. If buying your juice bottled, do your research first.

5. You May Be Setting Up Yourself for Weight Loss Failure

Simply put, juice cleanses don’t work. The idea behind a juice cleanse is that drinking juice as your only source of food allows your body to rid itself of “toxins.” But your body doesn’t need a cleanse, as it detoxes on its own. “Our bodies have their own elaborate, elegant detoxification system, called the liver, intestines, and kidneys,” says Dr. Youdim.

RELATED: The 10 Most Famous Fad Diets of All Time

6. You May Be Undernourishing Your Body When Using Juice as a Meal Replacement

A balanced meal contains the three macronutrients: carbohydrates, protein, and fat. “Juice is not a balance of these macronutrients, so it shouldn’t be a substitute for a meal,” says Johnston. Protein and fat are needed for fullness and satisfaction after a meal. Furthermore, a juice alone won’t deliver the nutrients needed to stabilize your blood sugar and give you the sustaining energy necessary to make it through the day, she adds. The addition of fat slows digestion, enhancing satiation, while protein helps balance your blood sugar. Juice lacks both of those things, and if you use them in place of meals for days on end — as in a juice “cleanse” — in order to lose weight, you’ll probably feel pretty terrible.

7. You May Be Unnecessarily Depriving Yourself of Fiber

“When you drink orange juice, you get vitamin C, but it’s not the same as eating an orange,” Simon says. That’s because juice removes the pulp — or fiber — necessary to keep your colon in good working order, reduce heart disease risk, lower cholesterol, and help improve blood sugar levels if you have diabetes. On the other hand, the whole fruit has the vitamin plus fiber, with far fewer calories than a glass of juice. For example, 1 cup of orange juice contains 110 calories, while an orange contains just 65 calories, according to the U.S. Department of Agriculture (USDA).

What’s more, you wouldn’t expect a juice to contribute to constipation — but that’s exactly what it may do, says Johnston. “Fiber is what makes up the indigestible part of our stool, and that’s the bulk of a bowel movement,” she explains. This bulk helps waste move through the intestinal tract quickly and easily. A juice on its own is okay, but only drinking juice on a cleanse is when things get problematic, as there’s no fiber to push through your GI tract to keep you regular.

RELATED: 11 High-Fiber Foods to Add to Your Diet

8. You May Suffer a Dreaded Blood Sugar Crash

“The reality is that nature is smart. Fruits that are higher in sugar come with a fibrous matrix to slow down the absorption of sugar. Without that fiber as a barrier, you’re giving sugar easy access, and it quickly absorbs into your bloodstream,” says Johnston. Otherwise, one glass of juice, if made with higher sugar produce, like apples and beets, can contain 20 to 25 grams (g) of sugar in a glass without the fiber to balance everything out, she notes. For example, 1 cup of unsweetened cranberry juice contains 30.6 g of sugar, per the USDA.

Foods that are high on the glycemic index (GI), including juice, cause a blood glucose surge. The GI indicates how quickly or slowly a food tends to release glucose into the bloodstream, according to Harvard Health Publishing. Juice is an example of a food high on the GI. Foods like this are lower in protein and fat and higher in carbs. Eating them can cause a spike in blood sugar that subsequently takes a dive, resulting in an energy dip, says Johnston. Headache and brain fog can also follow.

9. You’re Passing on Energy-Sustaining Protein

Again, having a green juice drink as part of your breakfast or lunch is totally fine. But have it alone and you miss out on the opportunity to get in protein. The macronutrient preserves and builds lean body mass, which helps keep you healthy and even burns calories, Youdim explains. Fruits and veggies on their own are not a great source of protein.

RELATED: 9 Best Protein Bars for Every Diet

10. You May Gain Weight if the Juice Is Packed With Calories

If made primarily of fruit, juices can be a serious source of sugar and calories, which, if not burned off, can lead to weight gain, according to research. If you’re going to enjoy a juice, it’s important to choose one that relies on greens and other veggies as the base, says Johnston. This can be bitter and borderline unpalatable for some people, she says. In that event, use lemon and ginger to add a hint of sweetness to green juice — but try to avoid larger amounts of fruit, which are higher in calories and sugar compared with veggies.

11. You May Be Wasting Your Money if You Choose to Do a Cleanse

A daily juice habit is expensive. A single Evolution Fresh juice can cost about $5, and a green juice from Pressed Juicery can run about $7. Cleanses are even costlier, and while some people may enjoy them, they are ultimately an unnecessary expense for health and weight loss. For instance, a three-day cleanse from Cooler Cleanse runs $174 for six drinks and 1,200 calories per day.

Bottom line: “If you want to live a healthy life and prevent chronic diseases without spending a fortune, eat whole vegetables and grains, not ‘detox’ [products],” says Youdim. If you are having a juice, go for a green juice with only added lemon and ginger. And keep your perspective: “Think of a juice as a way to drink a vitamin. You can get a lot of nutrients really quickly that way, but vitamins alone don’t make up a meal,” says Johnston.