ADHD and Diet, Food Color Controversy
By A. Minocha MD, author: Guide to Alternative Medicine and the Digestive System
ADHD, a common neurodevelopmental disorders presents with diverse clinical manifestations. The etiology/pathogenesis of this disorder continues to remain an enigma. A variety of hypothesis have been put forth in this context.
While genetic predisposition has been implicated, this does not explain the entire variance and as such the role of environment has been highlighted. Neurobehavioral toxicity may occur due to a wide variety of chemicals/toxins widely spread across the environment.
Potential environmental injury/toxic factors
- Toxin exposure (prenatal and perinatal)
- Birth injury
- Low birth weight
- Social conflicts and stress
- Intestinal milieu including bacteria
- Food additives/preservatives
Role of diet in historical context
Of the factors outlined above, the role of gut and diet has received increasing attention in recent years. These include the role of food allergies as well as exposure to food additives (colors and flavors) and preservatives.
1920s Food allergies were implicated in causing learning and behavioral problems.
1982 National Institute of Health (NIH) consensus development conference recommended further studies
1983 Kavale meta-analysis concluded that clinical impact of diet is too small to be meaningful
2004 Schab and Trinh meta-analysis concluded that artificial food colorings contribute to behavioral symptoms in hyperactive syndromes like ADHD.
2007 McCann population based study concluded that food colors and/or sodium benzoate preservative in diet is linked to hyperactivity in children.
2008 European Union Parliament imposed requirement for warning labels on foods containing six colors. Overall, the FDA approves 9 colors for use in foods of which Orange B is not approved in Europe. The synthetic colors requiring warning labels in Europe include Allra Red AC, tartrazine, sunset yellow, quinoline yellow, carmoisine and ponceau. The latter three are not approved in the U.S.
2008 Center for Science in the Public Interest (CSPI) filed a petition asking the FDA to regulate the use of food colorings.
2011 FDA concluded that scientific evidence did not support cause-effect relationship between food colorings and ADHD manifestations
2011 Food and Drug Administeration (FDA) approved synthetic colors include Brilliant blue, indigotine, green S or fast green, orange B, citrus, amaranth, erythrosine, allura red, tartrazine and sunset yellow.
2011 Stevens qualitative review of 35 years of research concluded that food additives play a role in a subset of ADHD patients and exclusion diets may be helpful in such cases.
The Stevens review also concluded that in kids with suspected senstitivies to synthetic food coloring additives, up to 89% improve when exposed to greater than 100 mg of artificial food coloring.
State of current literature on role of diet, food color additives and ADHD
The issue of role of food additives and ADHD continues to be mired in debate. The European and US authorities have taken different policy approaches to this issue.
Dr. Nigg and colleagues from the Oregon Health and Science University, Portland, OR,conducted a systematic review and meta-analysis in an attempt to review the up to date literature and hopefully resolve the controversy.
Their findings were published in an article titled, “ Meta-analysis of attention-deficit/hyperactivity disorder or attention-deficit/hyperactivity disorder symptoms, restriction diet, and synthetic food color additives” in the Journal of American Academy Child Adolescent Psychiatry (2012).
Methods of ADHD and diet, food coloring study:
- An extensive search of medical literature was conducted including Medline/PubMed.
- The 53 human studies published between 1976 to Feb 2011 were graded for relevance
- Overall 35 publications met the inclusion criteria.
- Rational grouping of parent/observer data
- Rational grouping of psychometric laboratory test data
- Meta-analytic computations were conducted using appropriate software.
Results of ADHD and diet, food coloring meta-analysis:
Effects of exclusion of food additives/colors as part of overall elimination diet:
- The results from open-labelled trials yielded a 47% response rate.
- The six controlled trials found that elimination diet that included eliminations of food colorings and additives result in a response rate of 41.5 percent.
- These results indicate that dietary restriction results in a reliable and clinically meaningful impact.
Role of synthetic food additives:
- The studies generally included subjects who had followed some kind of modified version of Feingold restricted diet and then were challenged with food additives in some fashion like cookies, capsules etc.
- For studies based on parental reports, the estimated size effect was 0.18 and was highly significant. Parents reported higher greater effects with higher doses without any impact of duration of exposure.
- For the 10 studies utilizing teacher/observer reports comprising a total of 323 subjects, the results on impact of food coloring showed a trend towards statistical significance (p=0.07).
- Six studies comprising 154 kids utilized psychometric tests of attention for analysis. The results revealed a reliable significant effect of food coloring on the psychometric tests in ADHD. The results were significant when studies included colors only or FDA approved colors only.
Proportion of kids reacting to colors:
- 14 studies comprising of 241 pre-seleccted kids responsive to elimination diets, studied proportion of kids reacting to colors.
- While the overall the event rate was 18 percent, it was 24% when only the studies utilizing well-defined criteria were analyzed.
- Using these results from preselected kids were diet responsive, it was estimated that 8% of kids with ADHD have symptoms related to food colors.
Conclusion of the ADHD, diet, food coloring study:
- Some kids with ADHD react to food additives as assessed by the parents; however it is unclear if this is due to FDA approved colors
- The results of studies utrilizing parent assessment versus teacher assessment are inconsitant
- Most studies examined effect of variety of combinations of colors thus rendering analysis of any specific color difficult.
- Inconsistency in parent-teacher observation studies notwithstanding, the studies utiliziing objective psychometric tests of attention showed reliable and significant effect of food colors with an effect size of 0.27. These affects could not be explained by publication bias.
- The adverse effect of food additives appears to be 1/3rd to 1/6th the size of effect of drugs used to treat the disorder.
- As many as 33% 9of kids with ADHD may respond to dietary exclusions. Since 8% have symptoms related to food colors, the precise mechanism for response to elimination diet remains obscure.
- There is paucity of studies dealing exclusively with FDA approved food colors or unselected study samples.
- Some of the kids sensitive to food color additives also display sensitivity to onsalicylate foods like milk, chocolate, soy, eggs, wheat, corn, legumes/lentils in addition to salicylate-rich foods like grapes, tomatoes, and citrus.
- Many experts argue that "cosensitivity" is more of a rule rather than an exception.
Other topics of interest:
- Autism, leaky gut and elimination diets
- Can probiotics strengthen selective intestinal barrier or leaky gut?
- Autism related to gut bacteria?
- Melatonin is not just for sleep. It helps gut too
- Toileting posture: Taking care of business well!
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