Along with losing fiber, there are other concerns. Vitamins are tricky things. Vitamin C and folic acid, for instance, start breaking down in the presence of oxygen, Snider notes. “Drink the juice fresh rather than making a batch and putting it in a fridge. The longer it sits, the more it interacts with oxygen.”
Juicers also need to watch their calories. Depending on how many juices you make a day—and the ingredients that you use—you could be consuming more than you think. One juice alone might contain two apples, 14 carrots and two small, peeled oranges, and the calorie count can exceed a soda. If you ignore the other carbs in your daily diet, your calorie intake can rocket. Moreover, a fruit-heavy drink can also cause a spike in blood sugar. Both are issues for diabetics.
If you have a chronic medical condition or you’re on medication, avoid certain fruits or vegetables. Vitamin K, which plays a role in blood clotting, can work against Warfarin, an anticoagulant medication. Leafy greens like kale are full of vitamin K. Vegetables that contain oxalates can lead to kidney stones. Raw cruciferous vegetables, such as Brussels sprouts and kale, can affect thyroid function. Talk to your doctor if you have concerns.
Also seek professional advice before embarking on a juice “fast,” Barr says. Your kidney and liver are designed to remove toxins.
Nevertheless, consumers like Theresa Vallier-Thomas felt inundated by toxins on the conventional over-processed and nonorganic foods. After being on a cleansing diet, she was ready to start fresh, and she’s been juicing about once a day since coming off the brief fast.
Use caution if you fast, says Kotanides. “I’ve done them, and you need to work up to them and then, afterward, introduce food gently back into your diet. Otherwise you can do more harm than good.”
Too many people eat heartily when they go off the fast, nixing the benefit, Kotanides says. Barr recommends working with a professional.