Are there any foods that can worsen mental health?!

Following on from my previous post on how to eat for mental health, today's post looks at whether certain foods can worsen mental health symptoms

While we know eating a mostly plant based diet rich in fibre and healthy fats can help mental health, are there other foods that can worsen it, and need to be avoided?

It's not just a matter of trying eat well - some foods have actually been found to negatively impact mental health

For example, highly processed vegetable oils have been linked with increased rates of anxiety (thought to be due to high ratio of omega 6 fats), whereas diets rich in omega 3 led to reduced anxiety (1) Another study showed increased rates of aggression in people who had diets high in omega 6 and low in omega 3 (2)
Interestingly, although people traditionally associate omega 3 with fish, some studies have shown that getting this from plants may actually be more beneficial for mood ( this may be due to higher levels of saturated fat and arachidonic acid (inflammatory fat) in meat eaters which counteracts the benefits of omega 3 from fish. ( Good plant sources of omega 3 are linseeds, chia seeds, walnuts, and leafy green vegetables

High GI foods (refined carbohydrates) have a direct link with increased rates of depression in postmenopausal women (23% increase between highest GI diets and lowest GI) (3) This same study found a similar association with added sugar - the highest sugar diets had 23% higher rates of depression compared to the lowest sugar diets

Other studies have shown the same link in middle aged women, college students, and the elderly, so it's logical to assume this is likely to affect all ages (4,5)

Anecdotally, when I suggest patients reduce or cut out added sugars and refined carbohydrates, they almost all report an improvement in mood and reduction in mood swings /irritability Given how we know these foods affect blood sugar levels (they shoot up then crash down) and inflammation (depression and anxiety have a very strong link with inflammation) it's a logical step to reduce intake

Meat is a debated topic with some metanalysis showing higher rates of depression with red meat consumption (6) and others showing a protective effect of small amounts of meat (1-2 servings/week max of red meat and 1-2 servings of white meat /fish) (7) I tend to take the view that small amounts of meat may be fine, in context of a mostly plant based (ie Mediterranean) diet. The second study was in a Greek population where the diet is naturally high in veges /legumes /olive oil As its known that high intake of red meat is associated with poorer gut biome diversity, its all about moderation and eating mostly plants

Several interventional studies have shown improvements in mood when people changed to a vegetarian diet, although whether this is due purely to the increase in plant foods independent of cutting out animal products is unclear

Many people with depression have elevated levels of MAO (monoamine oxidase) in the brain, which suppresses the 'happy hormones' (serotonin, dopamine)

MAO levels are reduced by quercetin, a phytochemical found in plants, which may contribute to mood improvement when plant foods are increased (rich sources are apple, kale, berries, green tea, onions, and grapes) (

Saturated fat has also been linked with higher rates of anxiety, especially in combination with high sugar (5x increased risk of anxiety). As the main dietary source of saturated fat is animal products, limiting these in favour of plant based fats, and choosing animal fats higher in omega 3 (ie fish) if you choose to eat meat, is a good strategy. (9)

As previously, eating a whole food Mediterranean style diet rich in fibre, lots of colorful fruit and veges, and good levels of omega 3 is the way to go

Dr uma naidoo is a nutritional psychiatrist, I love her resource on a mood healthy diet here https://www.the-well.com/editorial/what-to-eat-for-anxiety

Next post will be on supplements and mental health, so watch this space!!

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