The great thing about juicing fruit and vegetables is that you can drink far more nutrients in a sitting than you comfortably can by eating them. For example, drinking a quart of carrot juice is much quicker and easier than crunching on a dozen or so raw carrots. The main downside to juicing is that you lose most of the fiber, especially the insoluble type that’s commonly called roughage.
Juicing involves extracting the liquid from fruits and vegetables, which is in contrast to dropping them in a blender and making a smoothie. Smoothies are a quick and convenient way of consuming produce, too, but juicing is more like making a concentrated extract and requires special equipment. Old-school devices like mechanical presses work pretty well and can give your arm a good work-out, but there are also many electric juicing machines on the market that do all the work for you. It all depends on your budget and how much time you have to make natural juice.
Loss of Fiber
The main nutrient left behind when you juice produce is fiber. Fiber isn’t often called a nutrient because very little of it is metabolized and used by your body. Technically, fiber is a carbohydrate, but only a tiny percentage is broken down into simple sugar such as glucose and absorbed in your intestines. Most of the lost fiber is water-insoluble, such as cellulose, which is the main component in the cell walls of fruit and vegetables. Water-soluble fiber, such as pectin, is more likely to be in fresh-squeezed juice because it dissolves in liquid. For comparison, a medium-sized peeled orange contains about 3.5 grams of total fiber on average, whereas an 8-ounce glass of fresh-squeezed orange juice contains about 0.4 gram of soluble fiber and 0.1 gram of insoluble fiber for a total of 0.5 gram.
Importance of Fiber
Insoluble fiber dissolves in fluid and becomes sticky in the intestines, which enables it to adhere to cholesterol and various toxins and pull them out of your body. Consequently, insoluble fiber such as pectin and gums can help reduce blood cholesterol levels. In contrast, insoluble fiber attracts water but doesn’t dissolve in it so it tends to bulk up the stool and help clean out the large intestine. Insoluble fiber also promotes regular bowel movements and makes you feel full for longer periods of time.
Some powerful juicing machines produce a fair bit of heat, especially if you are using them for more than a few minutes. Some nutrients, such as vitamin C, are heat-sensitive and may be partially destroyed by using commercial juicing machines. To combat this problem, use mechanical juice presses and make sure to drink the juice fresh because exposing it to oxygen can quickly oxidize certain nutrients.
Some nutrients, especially antioxidants, are attracted to fiber and left behind with juicing, but the percentage is pretty low. For example, fresh-squeezed juice contains about 90 percent of its antioxidants, which means about 10 percent is left behind with the fiber.
- The Nutribase Complete Book of Food Counts; Art Ulene
- Human Biochemistry; Charles Dreiling
- Encyclopedia of Human Nutrition; Benjamin Caballero et al.
Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.