Diet and attention deficit hyperactivity disorder

For some children, diet is suspected of playing a role in the multiple behavioral and cognitive symptoms of attention deficit hyperactivity disorder (ADHD). Concerns have focused on food additives, blood sugar regulation, food allergies and intolerances, and vitamin, mineral and fatty acid deficiencies.

Food coloring and additives

Since the 1970s and the well-publicized advocacy of Benjamin Feingold, there has been public concern that food colorings may cause ADHD-like behavior in children.^[1] These concerns have led the FDA and other food safety authorities to regularly review the scientific literature, and led the UK FSA to commission a study by researchers at Southampton University of the effect of a mixture of six food dyes (Tartrazine, Allura Red, Ponceau 4R, Quinoline Yellow WS, Sunset Yellow and Carmoisine (dubbed the "Southampton 6")) and sodium benzoate (a preservative) on children in the general population, who consumed them in beverages; the study published in 2007.^[1][2] The study found "a possible link between the consumption of these artificial colours and a sodium benzoate preservative and increased hyperactivity" in the children;^[1][2] the advisory committee to the FSA that evaluated the study also determined that because of study limitations, the results could not be extrapolated to the general population, and further testing was recommended".^[1]

The European regulatory community, with a stronger emphasis on the precautionary principle, required labelling and temporarily reduced the acceptable daily intake (ADI) for the food colorings; the UK FSA called for voluntary withdrawal of the colorings by food manufacturers.^[1][2] However in 2009 the EFSA re-evaluated the data at hand and determined that "the available scientific evidence does not substantiate a link between the color additives and behavioral effects" for any of the dyes.^{[1][3][4][5][6]}

The US FDA did not make changes following the publication of the Southampton study, but following a citizen petition filed by the Center for Science in the Public Interest in 2008, requesting the FDA ban several food additives, the FDA commenced a review of the available evidence, and still made no changes.^[1]

There is no evidence to support broad claims that food coloring causes food intolerance and ADHD-like behavior in children.^[7]:452 It is possible that certain food coloring may act as a trigger in those who are genetically predisposed, but the evidence is weak.^[1][8]

Sugar regulation

A number of studies have found that sucrose (sugar) has no effect on behavior and in particular it does not exacerbate the symptoms of children diagnosed with ADHD.^[9][10][11] One study demonstrated the impact of expectancy effects in parents' perceptions of their children's hyperactivity after consuming sugar. In this study, parents who were told their child had ingested a high concentration of sugar in drink form (even though the drink was actually flavored with aspartame), reported their child as being more active, inattentive and resistant to parental demands. This was in comparison to the group who were told (accurately) that their child had ingested no sugar.^[12]

Omega-3 fatty acids

Some research suggests that children with ADHD may have low blood levels of essential omega-3 fatty acids.^[13] However, it is unknown if decreased blood levels of omega-3 fatty acids can cause or exacerbate ADHD or whether lower blood levels of omega-3 fatty acids associated with ADHD are caused by an underlying mechanism.^[13][14] Fish oils appear to reduce ADHD-related symptoms in some children. A double blind study has shown "medium to strong treatment effects of omega 3 fatty acids on symptoms of ADHD" after administering amounts around 1 gram for three to six months.^[15] Several other studies showed similar effects, especially of Omega 3 fatty acids with Zinc and Magnesium.^[16][17][18] A recent longitudinal study that examined the effect of omega-3 in an animal model of ADHD found gender-specific changes in all ADHD-symptoms.^[19] Thus though it is increasingly documented in clinical studies that omega 3 fatty acids provide a safe way to treat ADHD-symptoms the mechanism of the effect may interact with several other factors such as gender.

References