Packed with vitamins, minerals and antioxidants, juices are renowned as health-boosting beverages. Along with providing a concentrated source of nutrition, juicing is a convenient way to infuse your diet with healthy plant foods and reach the Harvard School of Public Health's recommendation of nine servings of fruits and vegetables per day. Yet the effects of juicing are not always beneficial: juicing also carries potential dangers that could cause unwanted side effects and threaten your health.
When fruits and vegetables are contaminated with disease-causing microorganisms, juicing can lead to foodborne illness. The Food and Drug Administration warns that raw produce can harbor pathogens responsible for cyclosporiasis, E. coli, hepatitis, salmonellosis and bacillary dysentery--which produce symptoms ranging from vomiting and diarrhea to kidney failure in extreme cases. Although pasteurization kills these dangerous organisms, juicing alone does not, and unheated juices made at home or at juice bars can potentially lead to illness.
Blood Sugar Regulation
Because juicing removes naturally occurring fiber from foods, your body absorbs juices more quickly than it does whole fruits and vegetables--which can lead to rapid rises in blood sugar rather than a sustained release of energy. According to the July 2008 issue of "Diabetes Care," increasing fruit and vegetable juice intake, as opposed to whole fruits and vegetables, raises your risk of developing diabetes. Sweet fruits--along with higher-sugar vegetables like carrots and beets--are particularly likely to spike blood sugar levels when they're juiced, which can pose problems for diabetics and others with blood glucose disorders.
Some fruits contain a type of indigestible sugar called sorbitol, which can cause digestive distress--especially when juiced into a more concentrated form. Prunes, pears, sweet cherries, peaches and apples all contain measurable amounts of sorbitol, according to the Baylor College of Medicine, and consuming the juices of these fruits can cause gas, stomach cramping and diarrhea in some individuals. Children may be at particular risk for digestive woes when drinking sorbitol-containing juices.
Juices--particularly fruit juices--are energy dense, delivering a high dose of calories relative to volume. Coupled with their lack of satiating fiber, juices may encourage excessive calorie intake because they provide concentrated energy without relieving hunger. As a result, frequently juicing your foods may hinder weight-loss efforts or contribute to weight gain, especially when compared to eating fruits and vegetables whole.
Frequently juicing fruits and vegetables high in beta carotene may lead to a condition called carotenemia, caused by high carotene levels in the blood. Although this condition won't harm your health, it results in aesthetic changes some individuals find unappealing--including yellow or orange pigmentation on your palms and the soles of your feet. Carotenemia is particularly associated with a high intake of carrot juice.