Learn how what you eat affects how you feel.
Learn how what you eat affects how you feel.
Related listening:
How Food Affects Mood (Part 1) (Nutrition Diva #282)
How Food Affects Mood (Part 2) (Nutrition Diva #283)
A provocative new study on ultra-processed foods (Nutrition Diva #735)
We need a better way to define ultra-processed food (Nutrition Diva #757 BONUS)
Research references:
Hello and welcome to the Nutrition Diva podcast. I’m your host Monica Reinagel. As you have probably seen or heard, May is Mental Health Awareness month so today I thought we’d take a look at the latest research on the interactions between diet and mental health.
There has been some research looking at specific therapeutic diets for the treatment of serious mental health disorders, such as schizophrenia and bipolar disorder. A ketogenic diet, which is high in fat and extremely low in carbohydrates was found to reduce psychiatric symptoms in a small clinical trial. Not surprisingly, it also helped to mitigate some of the negative effects the that the medications for these conditions can cause, such as insulin resistance and significant weight gain.
These side effects are often troubling enough that people discontinue taking their meds, which is usually quite detrimental to their ability to function. A diet that deals with some of those side effects could help people stay on their meds. And the fact that it can also lead to further improvements in their condition is a very big cherry on that sundae.
It’s exciting to see that dietary interventions could play such a significant role in the treatment of these very difficult psychiatric conditions. But the ketogenic diet, as a long term regimen, is quite restrictive and poses other potential risks. In the case of less severe mental health challenges, such as depression or anxiety, I’m not sure the benefits of a ketogenic diet would always outweigh the risks.
Fortunately a less restrictive and more balanced approach stills holds a lot of promise for those dealing with these very common conditions.
A number of different research groups have detected a link between diet quality and mental health. A study published in the American Journal of Psychiatry in 2010 looked at the dietary habits and mental health outcomes of over a 1,000 women. It found that women whose diet was higher in processed foods, refined sugars, and saturated fats, had higher rates of depression and anxiety compared to those whose diets included more whole foods, fruits, and vegetables.
More recently, a 2024 analysis of over 11,000 participants in the 1970 British Cohort Study looked at the relationship between vegetarian diets and psychological distress. The primary question these researchers wanted to answer was whether those who adopted vegetarian diets as young adults were either more or less likely to suffer from psychological issues later on. And those who reported being vegetarian at age 30 were no more or less likely to report mental health issues over the next 20 years. Weirdly, though, those who had mental health issues as kids were more likely to be vegetarian at age 30. Frankly no-one’s really sure what to make of that.
But, more to our point here, while vegetarianism didn’t increase or decrease risk, the researchers did see a link between diet quality and mental health–for both vegetarians and non-vegetarians alike. Once again, diets high in sugars and processed foods were associated with increased psychological distress and other mental health issues.
And, finally, a 2024 meta-analysis published in the British Medical Journal consolidated findings from several observational studies, revealing a consistent correlation between a high intake of ultra-processed foods (UPFs) and an increased risk of anxiety, depression, and other health issues
Now of course, all of these studies have limitations. Many rely on observational data, which can only show correlations and not causality. Maybe depression causes poor eating habits and not the other way around. (Most likely, it’s a bit of both.) Furthermore, I’ve shared some of my misgivings about the NOVA food classification system, used to decide which foods are considered to be UPFs, in previous podcasts.
The flawed criteria used in the NOVA system end up lumping a lot of perfectly nutritious, wholesome foods together with foods that have very little going for them nutritionally. So, while there may be a lot of benefits to reducing your consumption of nutrient-poor junk food–benefits that extend well beyond just supporting your mental health, I don't necessarily think that all of the foods being classified as UPFs need to be targeted.
And I’m really hoping that my voice and that of many others will prevent the NOVA system from being baked into our food policy. But I’m increasingly pessimistic that we will succeed in that effort.
In any case, beyond looking at overall diet quality, there are a few nutrients that we should include in our discussion of food and mental health.
Omega-3 fatty acids are often mentioned in this context, which makes sense when you consider how important omega-3s are to brain function. And there is some research to suggest that omega-3 supplements could be useful in the treatment of depression, particularly when used in combination with antidepressant drugs. The American Psychiatric Association currently recommends that individuals with a mood disorder should consume 1 g EPA plus DHA every day. (That would be a 1,000 mg supplement but a serving of salmon would also do the trick.)
For those who are not suffering from depression, you might wonder whether taking an omega-3 supplement might help keep the blues at bay. Unfortunately, the research to support that isn’t super strong. Researchers have looked for an association between omega-3 intake and depression risk and the results have been mixed. Sometimes, there seems to be no link. When they have detected an effect, it tends to be pretty modest.
The other nutrient that we should mention is folate, a B vitamin that’s found in leafy greens like spinach and kale, as well as beans and legumes. Studies have found that people with depression are more likely to have low folate levels. In these cases, increasing folate intake can help improve symptoms and even improve responses to antidepressant medications. For those without symptoms of depression (or a documented deficiency), I don’t think there’s enough evidence to support taking folate or folic acid as a supplement.
On the other hand, the healthy dietary patterns that have been linked to better mental health are likely to be good sources of both folate and omega-3, along with a host of other valuable nutrients. I know that upholding the overall quality of your diet takes a bit more effort than simply popping a vitamin. But on the plus side, the benefits of a healthy diet go far beyond mental health.
If you’re not quite sure where to start, check out my free Nutrition GPA app, which is designed to gently guide you toward the eating habits that have been linked to reduced risk of mental and physical health issues. It’s just structured enough to get you on the right track but still flexible enough to withstand the challenges of daily living.
You’ll find the Nutrition GPA in the Apple and Google app stores. Or you can check out my 30-Day Nutrition Upgrade program, which adds another layer of support to the app. You can learn more at https://nutritionovereasy.com/upgrade. Or if you’re interested in bringing the Upgrade program to your workplace, shoot me an email at nutrition@quickanddirtytips.com and we’ll figure out how to make that happen!
Nutrition Diva is a Quick and Dirty Tips podcast and is supported by Brannan Goetschius, Nathan Semes, Davina Tomlin, Holly Hutchings, Morgan Christianson, and Kamryn Lacy.
That's all for this episode. Thanks for listening! I'll see you next week.