Author: Susan R. Johnson MD, F.A.A.P.
Published: Sept 6th, 2001
I knew that drinking lots of apple juice wasn't good for toddlers because they often filled up on juice, and they wouldn't be hungry for meals, thereby missing vital food substances (proteins, fats, vitamins, minerals, etc). What I didn't realize was that drinking juice was like drinking concentrated sugar and could potentially deplete the body of valuable vitamins and minerals in a manner similar to eating lots of candy or drinking lots of soda.
For example, when a child eats an orange, it does so slowly, and receives minerals and vitamins within the orange itself that help it process the sugar. The body requires B vitamins (thiamine, folic acid, B12) and trace elements like zinc, chromium, and magnesium as well as several enzymes to process and store the sugar we eat. When a child consumes a large glass of orange juice, it is like eating 5 or 6 oranges in 30 seconds, and because most juices are pasteurized, vitamins and other nutrients are inactivated by the high temperatures. In addition, the large amount of sugar presented quickly to the body causes too much insulin to be released from the pancreas. This over-release of insulin causes the blood sugar to drop. The brain, now faced with an unstable supply of sugar, preferentially closes down the higher learning centers (memory, thoughts, social behaviors etc.), and instead stimulates the more primitive emotional and motor centers of the brain to deal with this perceived "crisis" (resulting in an overactive child that is emotionally "out of control").
The child and even the adult's body responds to the stress of low blood sugar by activating the "fight or flight" sympathetic nervous system: a response that creates jerky, impulsive body movements. In addition, the adrenal system is also activated and releases stress steroids in response to the low blood sugar. These steroids weaken our immune system (an important reason why one doesn't want to consume sugar when one is sick) and intensify feelings of irritability, anger, and even rage (i.e. temper tantrums).
An adult's digestive and nervous systems are more finely tuned. The adult may notice an increased in heart rate and feel a little light headed or sweaty from consuming too much sugar, but usually the adult's blood sugar can stabilize after an hour or so. For the child, it may take a four or more hours to stabilize the blood sugar after a bolus of fruit juice, soda, or candy. Each child is different, but diets high in sugar are believed to disrupt the child's neurological development by affecting the release of neuro-hormones. Some researchers also feel that the chronic overstimulation of the pancreas by a diet high in sugar may be contributing to the increase in Type II Insulin-dependent Diabetes now seen in children.
This past June, I attended a five day conference in St. Paul, Minnesota entitled "Incorporating Evidence-based Complementary and Alternative Therapies into Clinical Practice". The concensus was that fruit juices were not good for our children, and we all should be eating fruit instead of juice and drinking lots more water (8 oz of water for every 20 pounds of weight). Interestingly, the most recent newsletter from the American Academy of Pediatrics recommended that children should not drink more than 4-6 oz of juice a day.