Over the years one of the other questions I have received is about juicing. Quite often these questions came from people who watched a lot of late night TV and saw infomercials featuring people like Jack LaLanne, but I have received a few reports of people getting encouragement to "juice" from their health care providers as well. Does juicing do what it says it should and is it ok as a regular healthy practice? Let's see what the evidence says.
One claim made by juicing proponents is that juicing can reduce your risk of getting cancer, keep cancer from reoccurring, or cure the cancer that you already have. There is plenty of scientific evidence to indicate that people who have a higher fruit and vegetable consumption consume more anti-oxidants and other nutrients that can help reduce your risk for cancer. Does consuming the fruit and vegetable in a juice form up the risk reduction even more? Here the evidence is very shaky. For people who haven't been eating a lot of vegetables drinking the juice might be a way to easily consume more, but that just speaks to the consumption, not the form. As far as a high fruit and vegetable intake preventing cancer or curing what you already have? Well, maybe, but not b/c there is anything magical surrounding fruits and vegetables in their regular or juiced form. For some people cancer is a very rude awakening to the state of their health, and they start improving their health in a lot of different ways, such as quitting smoking, eating less processed foods, exercising more, building social relationships by attending support groups, getting more sleep, etc. Chances are they also ate more fruits and vegetables; and they might have juiced to include more. Was it the juice that helped their cancer go into remission or a combination of surgery, chemotherapy, better overall diet, better overall exercise, not smoking, etc? Hard to pin it down on just the juice. Bottom line—eating more fruits and vegetables, along with other lifestyle changes, may help reduce your risk of cancer and help improve your quality of life as part of your treatment for cancer but there is no evidence that juicing adds to the benefits.
A second claim is that juicing boosts the immune system. I have a sneaking suspicion that this claim may have stemmed from the belief that vitamin C "cures" colds and many people associate vitamin C with fruit juices. Unfortunately, there is no evidence that vitamin C prevents or cures colds (Link), so you could almost dismiss the immune boosting claims on this. However, fruits and vegetables are good sources of vitamin A, C, and E which do help support our white blood cells (which do fight bacteria, viruses, etc that enter our body), but we also get some of these same vitamins from organ meats (vitamin A) and nuts/oils (vitamin E). So, if you are not getting enough fruits and vegetables, you might be more vulnerable to succumbing to the common cold, but your immune system is also influenced by your sleep, how much protein you're eating, how you are handling stress, and of course, how often you wash your hands. But does putting the fruit through a juicer somehow boost your immunity? Once again we are faced with a lack of evidence. Bottom line—eating more fruits and vegetables, along with other lifestyle changes, may cause you to be less vulnerable to illness but there is no evidence that juicing adds benefits.
A third claim is that juicing helps remove toxins from the body. "Toxins" are basically the modern day equivalent of "imbalanced humors" or "miasmas" or even evil spirits that people used to think caused disease before we understood that viruses and germs did so. So if a toxin doesn't exist, anymore than miasmas do, then how can they be removed from the body? Of course there are poisonous substances out there, but they are not a secret and often the results of ingesting such poisons are known. Many of these "poisons" are derived from the "natural" world and many people ingest them willingly in the forms of alcohol, tobacco, and opiates (i.e. pain killers). If you are a smoker, the best way to get rid of the nicotine in your system is to stop smoking. I have seen people embark on a "juice fast" as part of their "detox" from nicotine or whatever they were "detoxing" from. Chances are they came through it feeling better because they were able to get through the initial nicotine withdraw but substituting a lot of sugary juices and they got the nicotine out of their systems. Bottom line—juicing does not help remove something that doesn't exist in the first place, and the best way to avoid "poisoning" yourself is to not take the poison in the first place or stop taking it.
The fourth claim is that juicing can aid digestion. There might actually be a grain of truth here. Most species on this planet have evolved with survival in mind. Plants cannot "run away" from creatures that want to consume it or climates that want to destroy it, so plants have had to develop ways to ensure their survival. Many plants contain substances collectively called "anti-nutrients" that prevent the absorption of many vitamins and minerals. Fruits and vegetables are no exception, although a lot of the modern day fruit and vegetables have been bred for increased palatability and ease of chewing. For the average person with a healthy digestive system, just chewing the raw fruits and vegetables well, or eating them lightly steamed or roasted, or even cooking them in a little fat, should give you access to enough vitamins and minerals. For someone who has an inflammatory bowel disease, or has damage to the digestive tract from chemo therapy, or who has lost the ability to chew because of a stroke, etc. The blender can help "pre-digest" the fruits and vegetables and help that person absorb vitamins better. Bottom line—if your digestion is already fine, blending won't help you, but if you have known damage to the GI tract you might benefit.
That last paragraph actually brings up another problem with juicing, and that is that sometimes the ability to consume and digest something quickly can be detrimental. Once again let me point you to yesterday's post where I gave a brief description about how overeating on carbohydrate (and ultimately protein) can lead to elevated insulin levels which can increase your hunger and cause poor glucose control (Here). So let's say that you are keeping your carbohydrate grams to no more than 15-30 per meal (or less if your blood glucose levels are wildly out of control), but you decide to do a juice recipe. I have seen fruit juice recipes that contain 30-60 grams of carbohydrate for one glass—so if you are not careful you could go way over limit. Now, if you are mostly doing vegetables you will likely do much better on the carbohydrate intake, but depending on the vegetables you consume you might get more carbohydrate and calories than you think. I can still remember the guy with uncontrolled diabetes who came to my office unable to comprehend why his blood sugars were going up when he was eating more vegetables with his juicer. Turns out one of his favorite recipes required 1.5-2 POUNDS of raw carrots, it would produce one large glass of juice, and he would drink the whole thing. If he would have eaten one carrot, he would have consumed about 5 grams of carbohydrate. With the juice, he was consuming 45-60 grams at one time, on top of all the other carb foods he was eating. Another problem with juicing is that we have evolved to "work" for our calories –which means our body is used to getting nutrients in smaller quantities (i.e. eat one orange instead of drinking a glass of juice that's the equivalent of 2-3 oranges). Our body is also used to receiving nutrients after we have chewed on the food and probably eaten in a fibrous form (and with some fat) to keep the food digesting at a normal pace. Bottom line—when food is in liquid form we absorb it quicker than our bodies are supposed to and this could lead to increased hunger, overeating, poor blood sugar control, and other problems w/elevated insulin levels.
Disclaimer: SkepticRD loves to have a quick breakfast, and when it's hot like it is here is Skepticville right now, cold fruits taste really good. When I need a quick and cold breakfast I have been known to do a smoothie. My damage control—measure out the amount of fruit I'm using, add protein powder to make it more of a meal, add some time of fat like coconut or avocadoes, and I add a green leafy vegetable like spinach. It's still liquid, but I've still got the fiber from the fruit and vegetables, the good fats to help me digest the meal at a regular pace, and I've kept my carb under control (and had protein too).
Take away message—unless you have trouble chewing or a damaged GI tract you can save your money on juicing. Keep eating fruit and vegetables raw or lightly cooked and you will still get the known benefits, just none of the magic.