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sábado, 25 de junio de 2011

Your Child's Diet: A Cause and a Cure of ADHD?

(Extraído de Healthy Children.org)

“You are what you eat” is a belief so prevalent in our culture—and true to some extent—that it is easy to understand the temptation to attribute ADHD-type behaviors to some dietary causes, or to believe that particular changes in diet can diminish the symptoms related to the condition. In fact, recent scientific research has supported the belief that diet and nutrition are related to mood and behavior, and that they can affect brain development in the early years. Add to this a widespread concern about the effects of sugar, artificial additives, and other elements in children’s diets and it is no wonder that special diets have become the most popular alternative to medication and behavior therapy treatment for ADHD.

Certainly, concerns about nutrition are valid for all children and should not be dismissed. It is also true that some forms of dietary management, and the addition of some trace elements through special supplements, may help with some specific health- or behavior-related problems. However, as you will see, none of the special diets designed to treat the symptoms of ADHD have yet been conclusively shown to be effective for most children with the condition.

Supplemental Diets

It stands to reason that an adequate diet is necessary for a child’s healthy growth. Proper nutrition, including an array of vitamins, minerals, amino acids, and essential fatty acids (EFAs), is particularly necessary in the first few years of life to support brain development and prevent certain neurological disorders. Even among older children, a lack of certain dietary components such as protein, or an insufficient number of calories, can negatively affect a child’s learning and behavioral abilities, and vitamin or mineral deficiencies can certainly interfere with learning over the course of a school year. Research shows, however, that a young child must be significantly malnourished in proteins and calories before brain development is seriously affected, and this level of malnutrition is rare in the United States. To date no convincing evidence has shown that a poor diet causes ADHD, or that dietary supplements can be used to successfully treat the condition.

Megavitamin Therapy

In the 1950s Drs Abram Hoffer and Humphry Osmond began using megavitamins containing large amounts of vitamin B3, vitamin C, and, later, pyridoxine (vitamin B6), to treat schizophrenia. This treatment was based on the theory that schizophrenia and some other forms of mental illness are caused by a genetic abnormality that greatly increases the body’s vitamin and mineral requirements. By providing patients with enormous doses (mega doses) of these substances, Hoffer and Osmond felt that psychiatrists could provide an “optimum molecular environment for the mind” in which the symptoms of mental illness would diminish or disappear.

In the 1960s the chemist and Nobel Laureate Linus Pauling put his support behind this theory, giving it the name orthomolecular psychiatry and greatly increasing its visibility among experts and the general public. In the 1970s Dr Allan Cott claimed that hyperactivity and learning disabilities were also the result of vitamin deficiencies and could be alleviated with megavitamins and large doses of minerals. Treating ADHD symptoms in children with nutritional supplements—supplements that contained at least 10 times the recommended daily allowance of vitamins, minerals, and other necessary elements—became an increasingly popular alternative to stimulant medication, particularly among families who considered megavitamins the more “natural” approach.

Research has failed, however, to reveal significant positive results from megavitamin therapy. While some early studies resulted in improved classroom attention ratings for subjects taking megavitamins, these studies were marred by the fact that the children, their parents, their teachers, and the researchers were all aware that a given subject was being given this new form of treatment. When the studies were repeated using the double-blind method discussed earlier, so that no one knew whether a particular child was taking a megavitamin or a placebo, no behavioral improvement was shown. In fact, it was discovered that disruptive behavior increased in a significant number of the children given the megavitamins. Studies have also suggested certain abnormalities in the way the liver functions among children on megavitamin therapy, signaling possible toxic effects of this high level of vitamin intake—a strong reminder that “natural” substances are not always safe, especially in the highly “unnatural” doses prescribed here. As a result, experts have concluded that megavitamin therapy for ADHD is of little benefit for nearly all children with the condition—and potentially harmful. In 1976 the American Academy of Pediatrics Committee on Nutrition issued a formal statement to that effect. This is not to say that children with ADHD should not take any vitamins, just that vitamins at normal doses and even mega doses are not in any way an effective treatment for ADHD.

Other Vitamin and Mineral Supplements

In the wake of the enthusiasm for megavitamin therapy, a number of specific nutritional elements have been studied regarding their possible role in the development of ADHD and their potential for treating the condition. These elements include iron, magnesium, pyridoxine (vitamin B2), zinc, and certain EFAs including linoleic acid and linolenic acid. All of these elements are known to be necessary for optimal brain development and function. Some studies comparing the levels of these substances in the blood of children with ADHD to their peers without the condition have even revealed lower levels of zinc or EFAs. (No difference between children with or without ADHD has been shown for levels of iron, magnesium, or vitamin B2). Despite this evidence, no links between these low levels and ADHD-type behavior have been established to date, and no significant improvement in ADHD behaviors has been demonstrated when supplemental doses of these substances are provided. As with all children, any nutritional deficiency should be corrected with a standard supplement or change in daily diet. But supplementation should not exceed the daily recommended allowance because higher levels of some elements (zinc in particular) can prove toxic.

Additional Supplements to Improve Performance

A number of other dietary supplements have been proposed to replace the use of stimulants in treating ADHD. Principal among these are no tropics, antioxidants, and herbs. Nootropics, specifically a substance called piracetam, have been advocated as cognitive enhancers for children with Down syndrome, dyslexia, and ADHD. While there is no scientific proof of positive effects relating to Down syndrome, one convincing study did show improvement in reading ability and comprehension among children taking piracetam supplements. While there is a rational basis for theorizing that piracetam may also improve ADHD-type behaviors because it is believed to enhance the transmission of the same brain chemicals influenced by stimulant medication (dopamine and noradrenaline), no controlled studies have yet been published, and so this treatment cannot be recommended.

Deanol (DMAE), lecithin, and phosphatylserine are other nootropics frequently found in over-the-counter ADHD remedies available in health food stores or on the Internet. Lecithin and phosphatylserine have not yet been sufficiently studied as treatments for this condition, but DMAE has seemed in one reliable study to be as effective as the stimulant methylphenidate in treating target behaviors. It is clear, then, that though these nootropics cannot currently be recommended as a substitute for stimulants due to insufficient evidence, they are currently being seriously researched and warrant further study as a potential future treatment for the symptoms of ADHD.

Antioxidants and herbs, used for many centuries in traditional medicine, have only recently come under scientific study. Some of the substances that have been marketed as treatments for ADHD include pycnogenol, an antioxidant derived from pine bark; melatonin, another antioxidant known to successfully treat sleep cycle disturbances in certain children; gingko biloba extract, often used in Europe to treat circulatory and memory disorders; and such herbs as chamomile, valerian, lemon balm, kava, hops, and passion flower. While melatonin can be useful in addressing sleep disturbances in a child with ADHD, and the herbs mentioned may also be useful as mild sleep aids, the reported positive effects of these antioxidants and herbs as treatments for ADHD’s core symptoms has been solely anecdotal so far, and there is insufficient scientific evidence to support their use.

If you do decide to administer any of these substances to your child, it is imperative to inform your child’s pediatrician and then carefully limit and monitor their use because some can lead to harmful effects if used in combination with other medications. Gingko biloba extract, for example, must not be taken with aspirin, anticoagulants, or antidepressants, and the herbs listed should not be used when taking sedative medications due to the danger of compounding the sedative’s effects. It is necessary to keep in mind that these substances can vary considerably in potency from one preparation to another, and that they are not standardized or regulated by the US Food and Drug Administration.

Elimination Diets

Other theories about the causes of, and treatment for, ADHD have evolved from the hypothesis that certain substances that are present, rather than absent, in a child’s diet may lead to or worsen the condition. The suspected harmful substances include artificial food additives, preservatives, sugar, or other elements speculated to cause allergic responses or yeast infections that can lead to the development of ADHD. According to these theories, eliminating such elements may eliminate or diminish the symptoms of ADHD.

Feingold Diet

In the mid-1970s a groundswell of concern about the effects of food additives, artificial flavorings, and dyes in the American diet accounted for, in part at least, the huge popularity of the Feingold Diet as a treatment for ADHD. Dr Benjamin Feingold, a practicing allergist, theorized that these food additives, as well as substances called salicylates (contained in many fruits and vegetables), were causing hyperactivity and learning disabilities in many children. In his book, Why Your Child Is Hyperactive, Dr Feingold claimed that when these children were given a special “elimination diet” that omitted these substances, half of them showed a dramatic improvement in behavior. When the elements were reintroduced into the children’s diet, the symptoms returned.

The Feingold Diet became hugely popular in the United States, not only in the population at large but among some ADHD experts and politicians as well. A National Advisory Board on Hyperkinesis and Food Additives was created, and The Feingold Association of the United States was established to support and provide information to parents. All of this activity occurred despite the fact that Feingold’s theory was based solely on anecdotal accounts and conjecture rather than conclusive scientific evidence—and the reality that these types of elimination diets are very difficult to carry out, particularly when the child is not at home where his parents can supervise his diet.

The good news was that the theory’s popularity increased public awareness of the presence of artificial additives in the diet and motivated more productive scientific inquiry into the relationship between diet and behavior. The disappointing news came in a subsequent series of studies revealing that only about 10% of children with ADHD demonstrated the predicted allergy to food dyes, and a mere 2% on the Feingold Diet showed consistent behavioral improvement when these food dyes were eliminated. Later studies provided a somewhat more positive slant: the small number of children who did respond negatively to food dyes benefited from them being eliminated (usually through decreased irritability and restlessness and improved sleep cycles), and most subjects’ parent ratings reflected some improvement in behavior even though their teacher and laboratory ratings did not. As a result, experts now recommend screening certain selected children for food sensitivities, although they do not support the use of the Feingold Diet to treat ADHD.

Diets Eliminating Sensitizing Food Substances

In the decades since the Feingold Diet was introduced; studies of the impact of diet on behavioral disorders have become more sophisticated and reliable. Newer research has shown that behavioral improvement using elimination diets is more likely in children who have inhaled and food allergies, a family history of migraines, and food reactivity. Younger children seem to be the most responsive. Whole foods like milk, nuts, wheat, fish, and soy have been implicated in addition to additives. Elimination diets can sometimes influence sleep and mood disturbances as well as ADHD symptoms. Sensitivities to substances in the environment—in medicines, clothes, water, our homes, the air, and so on—have also been studied as they relate to children’s health and behavior. The results have shown a link between sensitizing foods and some health and behavior problems in a small percentage of children with ADHD. In most cases, these children experience a variety of coexisting health and behavioral difficulties in addition to ADHD—particularly sleep-related and neurological problems. They are also likely to have a family history of food sensitivities or migraine headaches.

Because this link has been established, if food or additive sensitivities are highly suspected in your child, she may be tested for them by first eliminating an entire range of common foods (typically milk, soy, wheat, corn, citrus, and peanuts) for 2 to 4 weeks. If her symptoms improve—signaling the possible 248 presence of a food sensitivity—the range of foods can be restored to her diet, then one food at a time can be removed for a short period, with the results being monitored. This process can continue until the correct substance has been identified or all likely possibilities have been exhausted.

Elimination diets are often easier to introduce with young children, whose tastes in food may be easier to change. (Older children and adolescents are less likely to stick to a special diet.) They work best if you carefully target and quantify the behaviors you are hoping to improve. If these dietary changes prove to be extremely useful, a nutritionist can introduce you to tasty dishes that omit the offending food, and an appropriate support group can help with such issues as teaching your child to avoid the food away from home. As with the Feingold diet, these diets are difficult to integrate into daily routines. Children tend to resist diets that make them stand out from their peers, and it is often difficult for parents to devote the extra time to food preparation that these diets demand. As a result, you may experience considerable parent-child conflict when implementing one of these types of diets.

Meanwhile, it is important to understand that for most children with ADHD who do not have food sensitivities (and for some who do); elimination diets are not effective treatments for ADHD itself. If your child is on a special diet, you will need to make sure it is not replacing a more effective treatment for her ADHD. In most cases, stimulant medication, behavior therapy, and the other measures described in previous chapters will have a much clearer positive effect on your child’s ADHD-related behaviors, while a well-balanced diet with few processed foods may improve her general health and attitude.

Sugar-Free Diets

Humans are naturally attracted to sugar because it tastes good and because our bodies rely on glucose—the form of sugar found in natural foods—for metabolic processes. Like many other children, children with ADHD often have strong sugar cravings, and this has contributed to the belief that sugar and candy consumption can cause hyperactive behavior. A great deal of objective evidence, however, has shown that this assumption is untrue for most children with or without ADHD. While one early study did reveal a link between high sugar consumption and hyperactive behavior, there was no evidence that one caused the other or that the behavior problems were not due to different parenting styles or other factors. A number of subsequent scientifically rigorous studies could not demonstrate any adverse effects of sugar on the behavior of children. As for children with ADHD, sugar consumption has not been shown to cause or enhance ADHD-related behavior.

Of course allowing sugar only in moderation makes sense for any child. Major reductions or the elimination of sugar altogether, however, may create unnecessary conflicts with your child while providing few or no benefits. If your child shows an uncontrollable craving for sugar and carbohydrates, discuss this with her pediatrician. Aside from issues relating to general health, a sugar-free diet is not considered a useful tool in treating ADHD.

Aspartame-Free Diet

Aspartame, an artificial sweetener that became available in the early 1980s, consists of amino acids that cross from the bloodstream into the brain to affect brain function. (Interestingly, it was used as the placebo in some of the studies of sugar’s effects on behavior.) It was believed that among individuals susceptible to this substance, aspartame might lead to seizures or ADHD type behaviors. No such effects have been demonstrated, however, and elimination of aspartame for children with ADHD is not considered an effective treatment except for children with phenylketonuria, a chemical disorder that prevents some people from being able to break down or metabolize aspartame.

Yeast- or Fungus-Free Diets

In the mid 1980s, Dr. William Crook, a practicing pediatrician and allergist, popularized the theory that hyperactivity, irritability, and learning disorders in children could be caused by chronic candida (yeast) infection—the same type of yeast overgrowth that leads to vaginal infections in women. Crook pointed out that frequent or prolonged use of antibiotic treatment could pave the way for this type of infection because the antibiotics killed the bacteria that normally control the spread of yeast. To prevent this from happening, Crook devised a special diet eliminating all sources of sugar (because sugar leads to yeast growth) and all foods made with or contaminated by molds and yeast (such as breads, cheeses, dried fruits, and processed foods). He also recommended decreasing levels of additives and potential allergens in the diet, clearing the child’s environment of chemical pollutants and molds and providing vitamin and mineral supplements. For children with a history of antibiotic use, this elimination diet could be combined with such antifungal agents as nystatin or ketonazole to combat yeast without affecting useful bacteria. Finally, he recommended academic and behavior therapy support for all children with ADHD.

Crook claimed a success rate of 75% in reducing hyperactive behavior among his own patients with ADHD. However, his claims were based solely on his own professional observations rather than on any scientific study. While he speculated that yeast overgrowth produces toxins that weaken the immune system, thus leading to ADHD, he did not explain how the mechanism might work. (In fact, candida has not been shown to weaken the immune system, but to take advantage of an already weakened system to flourish.) Because there is insufficient objective research to validate Crook’s claims, because yeast infections have not been shown to cause ADHD, and because the often-recommended mega doses of vitamins can be potentially dangerous to your child’s health, this approach to treating ADHD is not recommended.

Last Updated
8/11/2010
Source
ADHD: A Complete and Authoritative Guide (Copyright © 2004 American Academy of Pediatrics)

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