[SPEAKER_00]: Welcome to Rethinking Wellness, a podcast that offers critical thinking and compassionate skepticism about wellness and diet culture and reflections on how to find true well-being.
[SPEAKER_00]: I'm your host Christy Harrison and I'm a registered dietitian, certified intuitive eating counselor, journalist and author of three books, including Antideite, which was published in 2019.
[SPEAKER_00]: The emotional eating, chronic dieting, binge eating, and body image workbook, which came out on February 20th, and the wellness trap, which was published in 2023 and is the inspiration for this podcast.
[SPEAKER_00]: You can learn more and get them all at ChristyHarrison.com slashbooks.
[SPEAKER_00]: Hey there, welcome to this episode of Rethinking Wellness.
[SPEAKER_00]: This is an audio version of my bi-weekly Q&A newsletter, which is also out today on Substack.
[SPEAKER_00]: I was working on this Q&A before the recent election made other questions feel much more pressing like the one I answered last week.
[SPEAKER_00]: But I think this one is still very relevant to the current moment in that it illustrates the stark divide between wellness culture, arguments, and science, and the importance of taking a critical and nuanced approach.
[SPEAKER_00]: Which are all important things to keep in mind in the years to come as misinformation about health and wellness and just life continue to proliferate.
[SPEAKER_00]: This question is about food auditives in ADHD and the top lane answer is available to everyone while paid subscribers can hear the whole thing for full context.
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[SPEAKER_00]: It really means the world to me.
[SPEAKER_00]: Now here's the question.
[SPEAKER_00]: The person writes, can you provide any insight to any impact food colors or additives have on ADHD?
[SPEAKER_00]: Is there a correlation or is it just BS?
[SPEAKER_00]: Just FYI, my answer's here for educational and informational purposes only.
[SPEAKER_00]: Aren't a substitute for individual medical or mental health advice and don't constitute a provider patient relationship?
[SPEAKER_00]: Also, I've never taken money from quote unquote big food or big beverage or worked with them in any way, and I never planned to.
[SPEAKER_00]: So there's a long-standing myth and wellness culture that artificial food colourings and other additives cause ADHD, but the science doesn't bear it out.
[SPEAKER_00]: Still, although food dies are not responsible for giving people ADHD in the first place, there's some evidence from randomized control trials that consuming artificial colourings may lead to a small increase in behavioral issues in a small subset of kids with ADHD.
[SPEAKER_00]: The research on other additives is much sparser and includes a number of dubious studies.
[SPEAKER_00]: Though, again, perhaps a small subset of kids with ADHD may respond to a more extensive elimination diet, or this finding may simply be the product of bias research, as we'll discuss.
[SPEAKER_00]: There's very little data on these questions in adults, but the same issues likely apply.
[SPEAKER_00]: The misleading idea that diet, quote unquote, causes ADHD first to cold in 1975.
[SPEAKER_00]: When an allergist named Benjamin Feingold published a book alleging that artificial colors, flavors, and preservatives along with a few naturally occurring compounds were the main cause of hyperactivity.
[SPEAKER_00]: ADHD didn't get its current name until 1987, but hyperactivity was sort of the label for this diagnosis at the time.
[SPEAKER_00]: These ideas and his uponmus find gold diet, which removed the offending additives, weren't based on any scientific evidence, but simply on the doctor's own experience and speculation, which of course are subject to many forms of uncontrolled bias.
[SPEAKER_00]: Even though there was no proof that his diet worked, it became popular among lay people and health professionals alike.
[SPEAKER_00]: Soon scientists did start testing the diet, and by the mid-1980s there were enough small, challenge studies where food additives were removed and then brought back to warrant a review and a respected pediatric sternum.
[SPEAKER_00]: The 1986 review found that just 1% of children had consistent improvements in behavior, based on parent or teacher reports, on the fine gold diet, and only 10% had an increase in symptoms when standardized food dyes were reintroduced.
[SPEAKER_00]: The review concluded that there was no evidence to support recommending dietary changes for kids with hyperactivity, the more recent evaluations suggest that a small subset of kids with ADHD may be sensitive to food colouring
[SPEAKER_00]: But the 1986 review seems to have had limited impact.
[SPEAKER_00]: Find gold advocates were numerous by that point, and the notion that food additives were responsible for hyperactivity had become something like conventional wisdom.
[SPEAKER_00]: A 1994 study, for example, used causal language, emblematic of some of the more dubious research in this area.
[SPEAKER_00]: Quote foods and additives are common causes of the attention deficit hyperactive disorder in children, and quote.
[SPEAKER_00]: It based this conclusion on results from just 26 kids with ADHD, only 16 of whom underwent a double-blind placebo-controlled food challenge, and children with pre-existing allergies had a significantly higher response to the challenge than those without, meaning that these results may not be generalizable beyond a subset of kids with ADHD.
[SPEAKER_00]: But that didn't stop the researchers from making a big leap to say that the condition itself is caused by foods and additives.
[SPEAKER_00]: A decade later, a 2004 meta-analysis shed some light on the issues with research in this area.
[SPEAKER_00]: The study evaluated 15 trials with a total of only 219 participants, including two studies with just one or two participants.
[SPEAKER_00]: They were all double-blind placebo-controlled trials, though not all randomized, but the researchers only gave two of the studies a ratings for quality.
[SPEAKER_00]: The analysis found that health professionals and teachers' ratings of kids' behaviors and response to artificial sweeteners were not statistically significant, but parents' ratings were, which may be because the outcome scales used to measure symptoms were non-standardized, and skewed towards things parents would be more likely to observe like sleeplessness or irritability.
[SPEAKER_00]: What's more, only trials that screen for responsiveness to dietary changes, according to parental reports are unblinded tests before enrollment, found a statistically significant effect of artificial colors.
[SPEAKER_00]: But an additional trial that screen participants prior to enrollment with a blinded trial of the fine gold diet did not show any statistically significant effects.
[SPEAKER_00]: This raises a couple of possibilities.
[SPEAKER_00]: One that the pre-screen kids were already more likely to be sensitive to dietary changes than the average ADHD population, or non-ADHD population for that matter, and two that there were placebo or no-sebo effects at play in the study populations, who may have already had placebo responses to food additives in the pre-screening process, or their parents who were more likely to enroll their kids in a diet study in the first place because they believe diets work,
[SPEAKER_00]: It's likely that possibility number two has biased at least some of the results in this area as several researchers have pointed out.
[SPEAKER_00]: But if possibility number one is also true, then there may be a small subset of kids with ADHD who are also sensitive to artificial food colourings.
[SPEAKER_00]: Indeed, at 2012 meta-analysis, which had similar discrepancies between parent and teacher reports, found that about 8% of kids with ADHD may have symptoms linked to artificial food colourings.
[SPEAKER_00]: However, the 2004 meta-analysis found that the effect of food coloring exposure among those kids is relatively small, only about a third to half the likely effect size of taking kids off-stimulate medications for ADHD.
[SPEAKER_00]: That is, medication still has a much stronger effect on ADHD symptoms, even in the possible subset of kids who are sensitive to food coloring.
[SPEAKER_00]: And the effect size for artificial food colorings was even lower in the 2012 meta analysis.
[SPEAKER_00]: So if there is a small percentage of kids who react to artificial food colorings, their reactions are likely small as well.
[SPEAKER_00]: Given the limitations of the existing evidence and the ongoing need for more research, I don't think it's wise to recommend as a general rule that kids with ADHD avoid artificial food colorings.
[SPEAKER_00]: Scientists still don't know the mechanism, if any, by which artificial food colorings might affect a small subset of kids with a condition.
[SPEAKER_00]: And as the 2004 meta analysis pointed out, the restructiveness of an AFC or artificial food coloring free diet may burden hyperactive children who are already at risk for poor psychosocial outcomes.
[SPEAKER_00]: And, quote.
[SPEAKER_00]: In fact, kids and adults with ADHD may have a higher risk of eating disorders, which makes any dietary restrictions especially risky.
[SPEAKER_00]: The only evidence I could find in adults, by the way, is a small pilot study from 2022, which involved just 18 ADHD participants and 11 controls, who were all randomized to a double blind placebo-controlled crossover challenge with artificial flu columns.
[SPEAKER_00]: It found that there were no significant differences in in attentiveness, scores on the adult ADHD self-report scale, or other attentional measures for either group in the AFC challenge periods.
[SPEAKER_00]: There were some small but statistically significant differences in two types of brainwave activity in the ADHD students after reintroducing artificial food colorings, but the researchers acknowledge that it's unclear how to interpret these results.
[SPEAKER_00]: They're simply exploratory.
[SPEAKER_00]: Now what about other additives?
[SPEAKER_00]: Artificial colorings are definitely the most studied food additive and ADHD that I could find, but some researchers have focused on other additives or overall restricted diets as well.
[SPEAKER_00]: Unfortunately, much of that research is shaky and some is incredibly shoddy.
[SPEAKER_00]: Take this retracted paper from 2022, which purported to review the harmful effects of various food additives.
[SPEAKER_00]: The dubious article, not a randomized controlled trial, made many leaps from correlation to causation, and said kind of activisty things like, we must take specific precaution to avoid consuming dangerous compounds before they begin to wreak havoc on our health.
[SPEAKER_00]: I would have been suspicious of this article even without the big red retraction notice at the top, but that made it all more clear that this was not real science.
[SPEAKER_00]: The publisher's investigation found evidence of quote systemic manipulation of the publication process, which, quote, undermines our confidence in the integrity of the article's content, and we cannot therefore vouch for its reliability and quote.
[SPEAKER_00]: A recent 2024 paper is different in that it hasn't been retracted, and its tone is less egregious, but it still uses advocacy language that isn't justified by its design, which is a literature reviewed not a randomized control trial.
[SPEAKER_00]: from the abstract it says, quote, little research has focused on children who are the largest consumers of UPS or ultra-processed foods.
[SPEAKER_00]: Potentially, they are a ticking time bomb for adult obesity, metabolic syndrome, cardiovascular diseases, mental health disorders, and cancers.
[SPEAKER_00]: Based on risk-benefit analysis, Azo die AFCs should be banned.
[SPEAKER_00]: Benzoates, multifiers, and sweeteners require assessment of quantitative limits and cumulative effects of combinations.
[SPEAKER_00]: Consumers purchasing UPS require information through ingredient health warnings and recommendations to use natural unprocessed foods, which have well-described health-promoting properties.
[SPEAKER_00]: The journal bills this paper as a review, but it reads more like an opinion piece with phrases like ticking time bomb and should be banned and a recommendation about health warnings on UPS and push consumers toward natural unprocessed foods.
[SPEAKER_00]: I don't have anything against opinion pieces.
[SPEAKER_00]: I sometimes write them myself, but this is not an unbiased scientific study.
[SPEAKER_00]: Instead, it seems like more hype about ultra-processed foods that's unwarranted by the science we have to date.
[SPEAKER_00]: As friend of the pod, Laura Thomas pointed out in the episode I did with her earlier this year about ultra-processed foods.
[SPEAKER_00]: That said, there is some limited evidence that a few foods diet, which is a descendant of the fine gold diet that eliminates many foods and additives, including artificial colors and flavors as well as lots of other food groups, may have some effect on behavior in kids with ADHD, though the data is mixed and should definitely be interpreted with caution.
[SPEAKER_00]: Previous systematic reviews have found that there was no significant effect of a few foods diet, but a 2017 systematic review reached a different conclusion.
[SPEAKER_00]: It analyzed the results of two previous meta-analyses of double-blind placebo-controlled trials of the diet and found an apparently larger fact.
[SPEAKER_00]: But that review has some serious conflicts of interest.
[SPEAKER_00]: The lead author, Lydie M. Pelser, is, quote, franchiseer of the restricted elimination diet or red protocol, meaning she benefits financially from recommending this diet, which is another name for the few foods diet in her home country of the Netherlands.
[SPEAKER_00]: Her Pelser Red Center's website translated from the Dutch uses causal language that goes far beyond what the research has really found, such as, quote, diet removes a cause of ADHD, medication only suppresses symptoms and quote.
[SPEAKER_00]: This conflict in Pelser's systematic review is akin to a pharmaceutical company finding that its weight loss drugs work, or weight watchers concluding that its diet program works, right?
[SPEAKER_00]: It's a major source of potential bias that means the results should be taken with a grain of salt.
[SPEAKER_00]: It's possible that this bias explains something odd I noticed about the waste statistics are handled in this study, which is that when Pelser and her colleagues analyze the results of previous meta-analyses, almost none were statistically significant.
[SPEAKER_00]: P was greater than 0.05, meaning that any differences between diet and placebo groups could simply be due to chance.
[SPEAKER_00]: But they gloss over that in the result section of the systematic review.
[SPEAKER_00]: And then in the discussion section, they make a big deal about how statistical significance can't tell this whole story anyway.
[SPEAKER_00]: And instead, they harp on effect sizes and confidence intervals.
[SPEAKER_00]: While there have been valid critiques of the over-emphasis on statistical significance in social science and in biomedical research, as well as some thoughtful responses to those critiques, I'm not sure if that's really why Pelser and her team took that stand.
[SPEAKER_00]: In fact, the same group of researchers went right back to reporting P values and emphasizing statistical significance in a 2020 study on the few foods diet, which had results that were more favorable to the diet and therefore to palcer's business.
[SPEAKER_00]: If their position on statistical significance in 2017 was genuine, it was also apparently short-lived.
[SPEAKER_00]: Beyond the conflicts of interest, the 2017 systematic reviews supplemental materials make it clear that any potential effect of a few foods diet or FFD only exist for a small subset of children with ADHD.
[SPEAKER_00]: As in the food coloring studies, the kids in the FFD trials were openly given the diet before randomization, after which only the kids who had a change in symptoms moved on to the next phase, which was an open challenge where one food a week was reintroduced pinpoint any reactions.
[SPEAKER_00]: Only then did the responders move into the double-blind placebo-controlled phase of the studies.
[SPEAKER_00]: So, the response rate really reflects kids with ADHD who are pre-selected for either a genuine response to foods, a placebo effect, or perhaps both.
[SPEAKER_00]: Indeed, Pelser and colleagues acknowledge the limitation that these studies may only have included parents interested in dietary treatment for ADHD, since that's who tends to sign up for a diet trial.
[SPEAKER_00]: The seeming effectiveness of a few foods diet in these kids could largely be a matter of parental placebo effect, where the parents are expecting to see benefits from the diet and so they do.
[SPEAKER_00]: Finally, even with the significant pro diet bias of the systematic review due to its conflicts of interest, the authors still caution that a few foods diet, quote, is not a long-term procedure, but a short-term diagnostic procedure, meant to identify any food sensitivities at which point children can be given personalized diet advice.
[SPEAKER_00]: They also acknowledge that this ultimate goal could take at least a year, and that it would be burdensome to families and might not be achievable, except by the most motivated parents with younger kids, who'd presumably be less likely to protest the restrictions.
[SPEAKER_00]: They conclude that, quote, large-scale implementation of the few foods approach would not be a realistic recommendation, and quote.
[SPEAKER_00]: So what's the bottom line here?
[SPEAKER_00]: Well, like so many areas of nutrition research, this one is fraught with limitations and conflicts of interest.
[SPEAKER_00]: Based on the available evidence, it's possible that a small subset of kids with ADHD would have a small reduction in certain symptoms if they avoided artificial food colorings, but we don't know who or why, since the mechanisms for this potential link are still unknown.
[SPEAKER_00]: And the potential drawbacks include increasing the burden on kids and families and putting an already high risk group of kids at even greater risk of disorder decay.
[SPEAKER_00]: So that's it for this solo episode.
[SPEAKER_00]: Thanks so much for listening and for your support as a paid subscriber, which means the world to me and my family.
[SPEAKER_00]: If you want to help support the show even more, I'd be so grateful if you'd take a moment to subscribe, rate, and review the podcasts wherever you listen, and also to share it with a friend who you think might enjoy it or share it on your social media platforms if you're there.
[SPEAKER_00]: If you have any questions for me about wellness and diet culture, you can send them in at christiharison.com slash questions.
[SPEAKER_00]: For a chance to have them answered on a future episode.
[SPEAKER_00]: And if you're looking for more in-depth help for healing your own relationship with food and breaking free from diet and wellness culture, I'd love for you to check out my online course in two of eating fundamentals.
[SPEAKER_00]: You can learn more in sign up at christiharisand.com slash course.
[SPEAKER_00]: Rethinking Wellness is produced and edited by softer sounds podcast studio.
[SPEAKER_00]: Julian Matasik does our website production.
[SPEAKER_00]: Our album art was created by Tara Jakobi.
[SPEAKER_00]: Our theme song was written in performed by Carolyn Penny Packer Riggs.
[SPEAKER_00]: And I'm your host and executive producer, Christi Harrison.
[SPEAKER_00]: Thanks again for listening and for supporting the show, and I'll talk to you again soon.
[SPEAKER_00]: Take care.