The link between nutrition and mental health is a new frontier for study but already there some patterns emerging.
The paragraph below is lifted from the 2017 study Gut microbiota’s effect on mental health: The gut-brain axis. Linked here
Gut health and mental health
Increasing evidence has associated gut microbiota to both gastrointestinal and extragastrointestinal diseases. Dysbiosis and inflammation of the gut have been linked to causing several mental illnesses including anxiety and depression, which are prevalent in society today. Probiotics have the ability to restore normal microbial balance, and therefore have a potential role in the treatment and prevention of anxiety and depression.
The study looks at the effects of probiotics, antibiotics and prebiotics as well as referencing the importance of having as diverse a gut flora as possible with and undamaged gut lining with low inflammation, so how do we achieve this?
Modern vs heritage foods
Our modern foods are not packing the nutritional punch that they used to. Factory farming and industrial preparation mean that we're eating more and getting less. This is explained in an article published in 2011 in Scientific American called 'Dirt Poor: Have Fruits and Vegetables Become Less Nutritious?'
In the article the author states “Efforts to breed new varieties of crops that provide greater yield, pest resistance and climate adaptability have allowed crops to grow bigger and more rapidly,” reported Davis, “but their ability to manufacture or uptake nutrients has not kept pace with their rapid growth.” There have likely been declines in other nutrients, too, he said, such as magnesium, zinc and vitamins B-6 and E, but they were not studied in 1950 and more research is needed to find out how much less we are getting of these key vitamins and minerals.
What can be done? The key to healthier produce is healthier soil. Alternating fields between growing seasons to give land time to restore would be one important step. Also, foregoing pesticides and fertilizers in favor of organic growing methods is good for the soil, the produce and its consumers. Those who want to get the most nutritious fruits and vegetables should buy regularly from local organic farmers.
The same applies to meats. We need heritage breeds, living longer on the land, fed a natural diet and interacting with the ecosystem to add complexity and diversity.
Animal based foods and mental nutrition
We know we all need to source our foods with more care but what about the macro effect of meats, grains and vegetables on our mental health?
A large study from April 2020 looked into this with frightening results.
The study linked here called 'Meat and mental health: a systematic review of meat abstention and depression, anxiety, and related phenomena' The conclusion was this.
The majority of studies, and especially the higher quality studies, showed that those who avoided meat consumption had significantly higher rates or risk of depression, anxiety, and/or self-harm behaviors. There was mixed evidence for temporal relations, but study designs and a lack of rigor precluded inferences of causal relations. Our study does not support meat avoidance as a strategy to benefit psychological health.
So why could this be the case?
There are 2 possibilities here, one is that the diet is causing the mental health problems and the other is that the mental health problem caused the diet. Either is possible and the truth might be a combination.
Considering the first study we mentioned, gut health is linked to diet and get health is linked to mental health.
Its safe to say that there are many important nutrients to us that are simply missing in plant only diets, these may be present in precursor forms requiring conversion or could be taken as supplements but if they are missing they will affect our health.
DHA & EPA
A very likely candidate for vegans having mental health problems is the essential Omega-3 Fatty Acids: DHA and EPA. These are important for brain function and are missing in non-animal foods. The form of omega-3 (ALA) found in plant foods is very difficult for the body to convert into DHA. At best, women convert only about 9% of the ALA they consume into DHA, whereas men convert a dismal 0-4%. Source
DHA is critical in the formation of healthy synapses (connections between brain cells), therefore infant brains require lots of DHA to develop properly. In short, DHA plays a “unique and indispensable role” in the “cohesive, organized neural signaling essential for higher intelligence” [Dyall SC 2015 Frontiers in Aging Neuroscience 7(52)].
The brain requires zinc for serotonin synthesis, vitamin B6 activation, and cell signaling.
Plant foods are far lower in zinc than animal foods. Zinc deficiency is much more common among vegans than iron deficiency, and yet gets far less attention. A 2017 Swiss study found that 47% of vegans had inadequate zinc levels compared to only 10% of omnivores. Some clinical trials show that combining zinc supplements with antidepressants improves outcomes, and there’s even been one randomized controlled trial demonstrating that zinc supplements alone can reduce severity of depression symptoms.
The list goes on, B12, K2, Choline , Carnosine, D3 and other B vitamins missing from plant only diets are linked to brain function which in turn could affect mental health.
In her article referenced above Georgia Ede MD states
'Many of the students I treat who choose a vegan diet only supplement B12, and some don’t take any supplements at all. The science is clear on this point: unsupplemented vegan diets pose great danger to brain health.'
What about the other possibility, that people with issues of anxiety and depression are more likely to be attracted to a controlled diet?
The article we referenced above 'Meat and mental health: a systematic review of meat abstention and depression, anxiety, and related phenomena'
Suggested that turning to a vegetarian or vegan diet could be a ‘behavioural marker’, meaning that these individuals were already experiencing poor mental health. This is definitely a possible reason for the link and would suggest that people with existing mental health problems try to control parts of their life and the world but omitting animal products from their diet, stres about the state of the world and the environment could cause a person to cut out a food group which could lead to an exacerbation of their mental health problems.
What's the solution?
The solution would appear to be to consume as wide a variety of foods as possible that have been grown as naturally as possible. Eat heritage plants, foraged wild plants, native breed animals which have been slow grown to maximise nutrition. If you are on a vegan diet, supplement to the best of your ability with nature identical supplements such as algae sourced Omega 3, a simple B12 pill won't guarantee your optimal mental health, neither will artificially fortified grains.