Juicing: Squeezing nutritional fact from fiction
You may have heard some of the following claims: gets rid of wrinkles, great for weight loss, gives your digestive system a rest, detoxifies your body and cures cancer – these are some of the health claims that proponents of "juicing" make. This popular part of the 60s and 70s health food movement seems to be back, with fresh juices standard fare in chic, health-focused eateries. With all dietary emphasis on eating more fresh vegetables and fruits and the many tantalizing health claims, you may think that juicing could be the ticket for a healthier you. So, what could a daily glass of liquid produce do for you?
Believe me, if juices could cure cancer (or get rid of wrinkles), I'd have invested in a juicer or a high power blender so that I could have more than the occasional prepackaged carrot juice. Unfortunately, very few, if any, of the juicing claims have scientific research to support them.
This is not to say that there are no benefits to juicing. Kale, spinach, beets and berries and some herbs are nutrient packed "superfoods". They are loaded with vitamins, minerals and other "phytonutrients" like antioxidant pigments that may reduce systemic inflammation (healthier blood vessels, decreased arthritis pain, etc). Their vitamins, minerals and antioxidant compounds will end up concentrated in your fresh juice. Very limited research shows some improvements in cognition and physical performance with frequent consumption of beet juice. But before you invest in a juicer or blender, give the topic and your own goals some thought.
Pluses for juicing or blending
Many of us worry about getting enough vegetables and fruits – eating more whole fruits and vegetables (but not juices) has been associated with less cancer, better brain health, lower blood pressure and a healthier body weight. According to the U.S. Center for Disease Control, a moderately active, older woman needs approximately 2 ½ cups of vegetables and 1½ cups of fruit per day; a moderately active, older man needs about 2 cups of fruit and 3 cups of vegetables.
A daily juice break could give you a nutrient rich boost and keep you focused on your healthy eating goals. For example, it will take about 4 cups of raw carrots to make 1 cup of carrot juice – this single serving of juice nearly fulfills the whole daily goal for vegetables and fruit and it provides nearly all the pro-vitamin A that you need for a week. Many people feel that the liquid form makes it easier to absorb the nutrients. Be aware that prolonged or exclusive liquid diets are not recommended without medical supervision – your digestive tract likes solid foods.
Of course, the goal also includes eating a variety of vegetables and fruits, so prepare for brilliant greens, reds or blues with the addition of some fresh spinach, kale, fennel, cabbage, beets, berries and some herbs like parsley, cilantro and dill weed. Apples, pears or cucumbers can add moisture and sweetness; lemons or limes will provide a nice balance of flavor and Vitamin C. Adding different vegetables and fruits will give you a greater variety of vitamins, minerals and other physiologically active compounds like antioxidant pigments.
While there is no scientific evidence that juices can cure any disease, juices can definitely pack a nutritional punch and make it easier to down a hefty serving of fruit or vegetables anytime of the day. For someone who may not be able to chew very well or who doesn't want to take time to cook a variety of vegetables, tossing some fresh options into a juicer may be the way to hit that target of increased fruits and vegetables. Juices can also be fortified with protein powders or food thickener to improve texture, flavor and overall nutrient package.
The following website can show you a personalized daily intake recommendation for vegetables and fruits based on your age, gender and activity level: http://www.cdc.gov/nutrition/everyone/fruitsvegetables/.
Cautions for juicing
There are a few things to keep in mind when making and using fresh vegetable and fruit juices. The first of these is that raw vegetables and fruits may be contaminated with e-coli, salmonella or listeria. Always wash and/or peel vegetables and fruits for juicing thoroughly and carefully to reduce potential contamination. Seniors or anyone with a compromised immune system may want to be very cautious.
Juices are highly concentrated. If you are taking Coumadin or blood thinners, remember that you should keep your intake of dietary vitamin K (found in green vegetables) consistent from day-to-day. A whole bag of spinach will make a very small drink (only 1/3 cup) but contain far more vitamin K than you would get in a serving of cooked spinach or cooked kale.
Other compounds in vegetables and fruits will also be concentrated and may cause stomach upset. Along with the all the good stuff, many foods contain some irritants or toxic compounds. One example is the indigestible carbohydrate in cabbage family vegetables that may cause gas and extreme stomach pain. Drink new juices cautiously and in small amounts to make sure that you do not have allergies or intolerances.
Raw cabbage family vegetables including kale, cabbage, Brussels sprouts and collards also contain compounds that interfere with thyroid hormone formation – these foods are referred to as goitrogenic, meaning that they interfere with thyroid hormone production. You may want to limit these or eat these only in the cooked form, especially if you have problems with hypothyroidism. Cooking cabbage family vegetables significantly reduces the goitrogenic compounds.
A final thought about juices is that they are missing one of the most beneficial parts of our vegetables and fruits, the fiber. Fiber may be a larger key to the benefits of vegetables and fruits than we have realized. Fiber is broken down by the 2-3 pound colony of microbes in your digestive system. The microbes produce substances that feed and keep the cells of the intestines healthy. Stay tuned for more information about this; but, if you juice, try to make use of the fiber in other ways, so that you get the benefit of the whole vegetable or fruit. Using a heavy-duty blender may be a great alternative to a juicer, creating an easy to swallow nutritious drink while retaining all the fiber. This type of blender has been shown to provide not just more fiber but also more of the other beneficial plant compounds.
Tips for buying and using a juicer
There are two basic types of juicers – the "centrifugal" and the "masticating". I've had both types and as a rule, the masticating type is easier to clean and may have a small advantage in nutrient retention of the product. Generally speaking the masticating types are quieter and transfer less heat to the juice. These work very well and extract nearly all the juice.
Besides the mechanics of the juice extraction and cleaning, another feature to consider is the size of the feed tube and how much work you have to do to push the food into the juicer. With some machines, you will have to cut your pieces of fruit into very small pieces (this will add some extra work to the process). Several other practical considerations are the size of the juicer and whether you have room on your counter so that you can use it easily, how often you have to empty to pulp container and whether you can easily collect the juice.
Regardless of the type of juicer you choose, always make sure that you clean your juicer thoroughly. Any area of the juicer that comes in contact with the vegetable, fruit or juice must be easily cleaned to prevent the growth of bacteria.
Juicers or blenders prices range from around $90 to $400 and higher, with better rated ones starting at around $150. Some less expensive ones get reasonable ratings but for frequent and heavy use you will probably want to purchase a slightly higher priced juicer or blender.
Leslie Shallcross is a registered dietitian and Associate Professor of Extension for the University of Alaska Fairbanks Cooperative Extension.