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California EPA Releases Landmark Report on Food Dyes

Confirmation of synthetic food dyes as a risk factor for ADHD.

Key points

  • ADHD is thought to be caused by a mix of genetic liability and accumulated environmental challenges.
  • Food dyes have long been suspected as one of the contributors, among others.
  • The California EPA has completed the most thorough examination of this issue ever done.
  • The agency recommended that steps be taken to reduce exposure to synthetic dyes in children.

It has been over a year, since just before COVID, that I last wrote a post about food and ADHD. It remains an active topic. A bit of quick review of what we know:

First, we know that brain function depends on an appropriate mix of minerals, vitamins, and enzymatic co-factors that enable efficient neural transmission. So major gaps in the diet can impair learning and attention. How much this influences ADHD has always been a question.

Second, we know from a fairly sizeable literature that kids with ADHD, on average, get a partial benefit from taking extra supplementation of omega-3 fatty acids (“fish oil”). However, this effect is small; certainly not big enough to replace standard of care. It may be a useful add-on in some cases. Further, new innovations like therapeutic dose minerals and vitamins are showing some promise in clinical trials.

Third, and my focus here, the literature on dietary restriction and allergens has been controversial. As far as I have been able to tell from our own reviews of the literature, a minority of children with ADHD do in fact benefit from restricting allergenic foods. This is where the question of food dyes and nutrients gets interesting.

One of the longstanding but controversial claims about ADHD has been that synthetic food additives, in particular types of food colorings (dyes), can provoke ADHD symptoms. Several previous reports have attempted to synthesize this disparate literature in quantitative meta-analyses that have usually concluded there is an association (causally) of food dyes in food and ADHD symptoms. But the literature has had numerous weaknesses that have enabled the FDA to avoid action. In Europe, however, regulators have instituted requirements for warning labels on foods with certain synthetic dyes in them. They were persuaded by a series of three clinical trials in Britain that all showed some population effect on ADHD symptoms.

Now the new development. Last month, the California EPA completed the most comprehensive integration of the entire animal, human, and mechanistic literature on food dyes ever done. The wealth of evidence reviewed and the systematic approach used lends a high degree of credibility to the report. They concluded that food dyes do pose a public health risk that warrants some action be taken to reduce exposure to these dyes in children. The California legislature is already considering introducing legislation to require warning labels on food and beverages containing synthetic dyes. (Industry representatives disagree.) While the overall population effect is small and is not the main cause of ADHD, potentially tens or even hundreds of thousands of children may be affected. That fact is sufficient for actionable concern.

This finding supports the findings of multiple independent reviews of the evidence, as well as the concerns of parents and advocates who concluded that for ADHD, avoiding synthetic food dyes is one worthwhile move. Some clinical trials, as well as individual anecdotal reports, suggest some children may have severe sensitivities.

Keep in mind that for the most part, the environmental influences on ADHD probably act in a cumulative fashion—the more challenges to the child’s body and brain, the more likely symptoms will emerge or worsen. Thus, our task as caregivers and clinicians is to remove the challenges we can, and provide the support we can, knowing we cannot and likely need not get every single one.

In that context, I always caution parents that it is important to recognize that avoiding these dyes may be difficult depending on your child’s current dietary habits. Bottled drinks and packaged foods are the main sources. Limiting these is the key. But place all of this in the context of other basic health-related strategies that can help with ADHD. These include: an overall healthy, fresh food diet; regular exercise; stress reduction; and minimizing pollution exposure. Do what you can—none of us can do it all. Every little bit can help!

Please note: Dr. Nigg cannot advise on individual cases for ethical, legal, and logistical reasons.


California Office of Environmental Health Hazard Assessment (OEHHA). "Report Links Synthetic Food Dyes to Hyperactivity and other Neurobehavioral Effects in Children." April, 2021.

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