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Glenn D. Braunstein, M.D.

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Don't Get Punch Drunk Over Extreme Health Claims for Juices, Juicing

Posted: 03/05/2012 2:18 pm

It's yet another of the fancy, shiny and pricey purchases or gifts parked on the kitchen counter. It may have gotten a good run just after the holidays when it got into the house and members of the whole family -- just as the infomercials, some celebrities and even a popular documentary advise -- pledged to try to boost their health with fresh-pressed juice. To hear their advocates, liquefied fruits, veggies and herbs -- especially greens like spinach, kale, cucumbers and wheatgrass -- offer an amazing elixir to lose weight, boost the body's immunity, prevent cancer, and cleanse the liver and colon -- and more.

Be careful of the rutabaga truck you fall from if you buy all these claims.

"Organic green juice is like red lipstick: don't leave home without it," preaches self-described "wellness warrior" and cancer survivor Kris Carr in her recent New York Times best-seller Crazy, Sexy Diet.

Well, OK, research shows that a diet high in fruits and vegetables can reduce the risk for many leading causes of death, including cancer and heart disease, as well as help with weight management. Most adults should eat at least nine servings (4½ cups) of vegetables and fruits daily (sorry, potatoes don't count). But few of us do. According to a 2009 survey by the Center for Disease Control, just 32.5% of adults consumed fruit two or more times per day and 26.3% eat vegetables three or more times per day. A healthy diet also should include a variety of types and colors of produce.

If juicing helps you achieve this, then puree away. There is no evidence, however, that juice is healthier than eating whole fruits and vegetables and those gullible enough to swallow the extreme assertions about juicing's benefits ought to be sent to bed with just a plate of Brussels sprouts.

Today's home juicers range from simple $30 models to $300 power machines that can pulverize an entire apple, core and all, in mere seconds. If you do juice, be sure first to wash fruits and vegetables thoroughly with water and preferably, a vegetable brush. This is key with fruits like cantaloupes and other melons that require peeling or cutting. Cut away those damaged or bruised areas; bacteria can thrive there. And only make as much juice as you can drink at one time, as bacteria can grow in the sugar-rich environment after squeezing.

Fiber is Filling, not Fattening

Because most fruits and some vegetables (most notably carrots and beets) are high in sugar, juicing is not recommended on a regular basis for diabetics. Juice is metabolized in the body more quickly than whole fruit and leads to quick spikes in blood sugar. If weight loss is the goal, juicing may not be the best bet either. Even raw juice is high in sugar and calories; some fruit juices actually contain more calories than soda. Another concern is that juice does not contain fiber, which is what gives us the feeling of fullness.

"Fiber, due to its bulky nature, stretches our stomachs. Our stomach receptors then signal the brain telling us that we're full," explains my colleague Jennifer Arussi, a registered dietitian. "Without that feeling of fullness we have a greater potential to over eat."

Fiber supplementation in the obese has been shown to enhance weight loss significantly. Plus, most adults get less than half the recommended amount of fiber in their daily diets.

Proponents of juicing claim that nutrients are better absorbed by the body in juice than whole fruit, but there is no convincing scientific evidence to support this. Advocates also assert that drinking juice gives the digestive system a break from working on fiber. But fiber actually aids digestion.

Limited Scientific Research on Healing Properties

Different proponents promote specific juices for their ability to prevent or remedy diseases and other medical conditions. Wheatgrass, a juicer's staple, for example, long has been touted for everything from the common cold to colitis to shrinking tumors. Wheatgrass provides a concentrated amount of nutrients, including iron, calcium, magnesium, amino acids chlorophyll, and vitamins A, C and E. Individual accounts have reported benefits of a wheatgrass diet, but there isn't sufficient scientific literature to support the extravagant promises made for this common plant. Pomegranate juice more recently has been the subject of boasts about its claimed anti-cancer properties. The ellagic acid in pomegranates has shown some positive results in the lab but proponents lack the clinical proof that it helps with disease in humans.

In some instances, the health benefits of fruits and vegetables can be tracked back to their skins, which don't always make it into juice. In a recent study published by my colleagues and I, premenopausal women who drank eight ounces of red wine slightly lowered their estrogen levels while increasing their blood testosterone concentrations, most likely due to a natural inhibitor of an enzyme that converts testosterone to estrogen. This inhibitor is found in the skins and seeds of red grapes, but is not found in the grapes that are used to make white wine.

Despite its fashionable status, juicing isn't exactly new. The movement couldn't have a more persuasive pitchman than health and fitness pioneer Jack LaLanne, whose famous feats include celebrating his 70th birthday by towing 70 boats with 70 people for 1 ½ miles in the Long Beach Harbor, while shackled and handcuffed. (I'll have whatever he's having). Before his death last year at age 96, LaLanne and his wife spent years promoting the Jack LaLanne PowerJuicer in televised commercials and infomercials. LaLanne also had a juice bar in the first gym he opened in Oakland in 1936.

The current craze has been fueled by reports on the eating habits of celebrities such as Gwyneth Paltrow and Selma Hayek, hip juice bars like Beverly Hills Juice and New York's Liquiteria and hundreds of books and websites offering recipes for the likes of "Kale Lemonade" and "The Only Way I Can Tolerate Beets Juice." Starbucks is jumping on the juice band wagon, too. In November, the coffee giant purchased Evolution Juice, a manufacturer of raw juices sold in stores and is planning to open its own juice bars. The first is supposed to open on the West Coast later this year.

Flushing Out the Facts On Juice Fasts

Feeding the liquid frenzy, too, is a recent documentary, Fat Sick and Nearly Dead. Credited with doubling the sale of the Breville brand juicer last year, the film chronicles Australian entrepreneur Jim Cross's 60-day juice fast and transformation from tubby and sick (he suffers from a skin condition called urticaria) to trim and healthy.

Swapping burgers and buckets of chicken for two months of just juice may melt the pounds away. But for most people, this isn't a medically advisable course. Extreme juicing, marketed as "juice cleanses" or "juice fasts," differ; these generally involve fasting or food restriction for varying spans and may include some combination of nutritional supplements. Some regimens recommend colonics or enemas, too.

"Fasting for a day probably won't hurt you," says my colleague Arussi. "But when you don't eat actual food," she adds, "your body produces hormones that say 'feed me' and you feel an intense urge to eat."

Much of what you'll drop via a juice fast will be water weight. Short-term side effects can include dizziness, nausea, constipation, fatigue and irritability. Longer fasts may cause electrolyte imbalances and if you don't consume enough calories to keep your metabolism functioning, your body will convert to energy crucial muscle tissue rather than fat (see my prior blog on this topic).

As for cleansing the toxins from your body, there is no scientific evidence that juice fasts do this; the liver and kidneys efficiently process and eliminate toxins on their own. For those taking medication for their heart or to regulate blood sugar, such programs can cause serious complications. And it goes without saying that children should not be put on juice fasts at home. If you must do these "cleanses," please talk to your physician first.

I think most MDs will echo my prescription: juicing can provide a possible alternative to a Popeye lifestyle of consuming gobs and gobs of spinach or other healthy foods to meet the daily requirements of fruits and vegetables. Your health, though, isn't something that can be reduced to cartoon-like thinking and consumers should sip with care any crazy Kool-Aid claims about juicing's boons: the diet to maintain good health should include minimally processed foods, lean protein and plenty of whole fruits and vegetables.

 
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