Historically, fruit juice was recommended by pediatricians as a source of vitamin C and an extra source of water for healthy infants and young children as their diets expanded to include solid foods with higher renal solute. Fruit juice is marketed as a healthy, natural source of vitamins and, in some instances, calcium. Because juice tastes good, children readily accept it. Although juice consumption has some benefits, it also has potential detrimental effects. Pediatricians need to be knowledgeable about juice to inform parents and patients on its appropriate uses.
A study this year found no association between childhood obesity and 100 percent fruit juice with no sugar added. “That’s big news, and it’s made a difference in what I tell my patients,” says Rockwell, D.O., assistant professor in the Department of Family Medicine at the University of Michigan Health System.
Other studies, meanwhile, have found that many fruit juices provide powerful health benefits, Rockwell notes. Research in recent years has identified ways that beverages such as pomegranate, orange and cranberry juices can help to prevent or cure diseases.
JUICES THAT PROVIDE HEALTH BENEFITS:
- Pomegranate juice. Pomegranate juice has received a great deal of attention in recent years for its reported benefits. It is a rich source of antioxidants and has been shown to lower LDL cholesterol – the bad, artery-clogging portion of one’s cholesterol, Rockwell says.
It also may slow the growth of prostate cancer. Pomegranate juice has been shown to stabilize the levels of men’s PSA, or prostate specific antigen. This protein in the blood is measured to gauge how quickly a man’s prostate cancer is progressing. Another study found that pomegranate juice may increase blood flow to the heart in people with ischemic coronary heart disease.
- Orange juice. The iconic breakfast drink may help people prevent recurrences of painful kidney stones. A study has found that a daily glass of orange juice can reduce the incidence of kidney stones better than other citrus drinks, such as lemonade.
- Cranberry juice. Long thought of as a home remedy for urinary tract infections, cranberry juice now appears to be most helpful before the UTI even develops. Studies indicate that cranberry juice is effective at preventing a UTI, but not at curing an existing infection, Rockwell notes.
- Blueberry juice. Blueberries have some of the same properties as cranberries that allow it to prevent UTIs, Rockwell says.
Other studies have indicated that an overall increase in consumption of fruits and vegetables reduces one’s risk of developing Alzheimer’s disease. A 2006 study showed that people who drank fruit or vegetable juices more than three times a week were 76 percent less likely to develop Alzheimer’s than those who drank juice less than once a week.
Drinking fruit juice is not an inherently healthy activity, however. Rockwell warns that many juices contain high levels of corn syrup, typically high fructose corn syrup. She says consumers should look for 100 percent natural fruit juice to avoid corn syrup.
“Corn syrup is related to many bad health issues, such as higher blood sugar and obesity,” Rockwell notes. “It leads to the buildup of fat cells, and contributes to the obesity problem in the U.S. and other industrialized nations.”
JUICES GIVE YOUR DIGESTIVE SYSTEM A REST
The benefits derived from drinking natural juices depend, in part, on the type of equipment used to make the juice. Centrifugal-force juicers — the traditional kind sold in many stores — remove virtually all of the fiber from the raw foods. Fiber is an important nutrient for digestive health that many Americans already consume too little of. However, this type of juicing may have health benefits for people with impaired digestion. Drinking juices made with traditional juicers gives your GI system a timeout while still providing all the vitamins, minerals and phytonutrients of fresh produce, says Dr. Sears Wellness Institute.
BLENDED JUICES DELIVER FIBER
Fresh juice made using a high-speed blender retains most of the fiber of its raw-food ingredients. Because of the fiber content, blended juices provide a slow release of nutrients into your bloodstream and can help you feel full longer. This may assist with your weight-loss efforts, reducing the number of calories you eat overall. It can also help you manage your blood sugar levels, preventing spikes and crashes that can affect your mood and energy.
JUICE UPS PRODUCE INTAKE
Increasing your vegetable and fruit consumption can reduce your risk of high blood pressure, heart disease and cancer. However, only 27 percent of Americans meet the daily recommendation of three or more servings of vegetables, and only a third eat the recommended two servings of fruit per day, according to a 2009 report by the Centers for Disease Control and Prevention. Juicing helps you consume more vegetables and fruits in a convenient, drinkable form. This boosts your intake of micronutrients and phytonutrients, helping to strengthen your immune system and ward off chronic illness.
CONSIDERATIONS ABOUT NATURAL JUICES
If you decide to add natural juices to your regimen, drink the fresh juices directly after they are made for the best health benefits. Natural juices are subject to both bacterial growth and rapid nutrient loss, reports CNCA Health. In addition, fresh juices made primarily from fruit are high in sugar and calories and may defeat your health goals. CNCA Health also warns that juicing too much of certain vegetables, like oxalate-rich leafy greens, can impair kidney health. Eat fresh raw and cooked produce in addition to juicing — your body absorbs some nutrients, like the beta carotene in carrots, better when the veggies are cooked and not raw.
COMPOSITION OF FRUIT JUICE
Water is the predominant component of fruit juice. Carbohydrates, including sucrose, fructose, glucose, and sorbitol, are the next most prevalent nutrient in juice. The carbohydrate concentration varies from 11 g/100 mL (0.44 kcal/mL) to more than 16 g/100 mL (0.64 kcal/mL). Human milk and standard infant formulas have a carbohydrate concentration of 7 g/100 mL.
Juice contains a small amount of protein and minerals. Juices fortified with calcium have approximately the same calcium content as milk but lack other nutrients present in milk. Some juices have high contents of potassium, vitamin A, and vitamin C. In addition, some juices and juice drinks are fortified with vitamin C. The vitamin C and flavonoids in juice may have beneficial long-term health effects, such as decreasing the risk of cancer and heart disease. Drinks that contain ascorbic acid consumed simultaneously with food can increase iron absorption by twofold.This may be important for children who consume diets with low iron bioavailability.
Juice contains no fat or cholesterol, and unless the pulp is included, it contains no fiber. The fluoride concentration of juice and juice drinks varies. One study found fluoride ion concentrations ranged from 0.02 to 2.8 parts per million. The fluoride content of concentrated juice varies with the fluoride content of the water used to reconstitute the juice.
Grapefruit juice contains substances that suppress a cytochrome P-450 enzyme in the small bowel wall. This results in altered absorption of some drugs, such as cisapride, calcium antagonists, and cyclosporin. Grapefruit juice should not be consumed when these drugs are used.
Some manufacturers specifically produce juice for infants. These juices do not contain sulfites or added sugars and are more expensive than regular fruit juice.
ABSORPTION OF CARBOHYDRATE FROM JUICE
The 4 major sugars in juice are sucrose, glucose, fructose, and sorbitol. Sucrose is a disaccharide that is hydrolyzed into 2 component monosaccharides, glucose and fructose, by sucrase present in the small bowel epithelium. Glucose is then absorbed rapidly via an active-carrier–mediated process in the brush border of the small bowel. Fructose is absorbed by a facilitated transport mechanism via a carrier but not against a concentration gradient. In addition, fructose may be absorbed by a disaccharidase-related transport system, because the absorption of fructose is more efficient in the presence of glucose, with maximal absorption occurring when fructose and glucose are present in equimolar concentrations. Clinical studies have demonstrated this, with more apparent malabsorption when fructose concentration exceeds that of glucose (eg, apple and pear juice) than when the 2 sugars are present in equal concentrations (eg, white grape juice). However, when provided in appropriate amounts (10 mL/kg of body weight), these different juices are absorbed equally as well. Sorbitol is absorbed via passive diffusion at slow rates, resulting in much of the ingested sorbitol being unabsorbed.
Carbohydrate that is not absorbed in the small intestine is fermented by bacteria in the colon. This bacterial fermentation results in the production of hydrogen, carbon dioxide, methane, and the short-chain fatty acids—acetic, propionic, and butyric. Some of these gases and fatty acids are reabsorbed through the colonic epithelium, and in this way, a portion of the malabsorbed carbohydrate can be scavenged. Nonabsorbed carbohydrate presents an osmotic load to the gastrointestinal tract, which causes diarrhea.
Malabsorption of carbohydrate in juice, especially when consumed in excessive amounts, can result in chronic diarrhea, flatulence, bloating, and abdominal pain.Fructose and sorbitol have been implicated most commonly, but the ratios of specific carbohydrates may also be important.The malabsorption of carbohydrate that can result from large intakes of juice is the basis for some health care providers to recommend juice for the treatment of constipation.