Human Health

Meat and other animal-sourced foods protect mental health

Is there a link between dietary choices and mental well-being? Yes. Nutrient-dense foods such as meat, fish, eggs, and liver provide bioactive compounds that are critical for brain health, neurodevelopment, and cognitive function. With the growing prevalence of mental and neurological disorders in today's society, it is crucial to examine whether deficiencies in these compounds could contribute to such conditions. Studies do indeed suggest a potential link between vegetarian diets, restricting such foods, and higher rates of depression and anxiety. However, it needs to be understood whether this association stems from vegetarianism being a direct cause or if, instead, underlying mental health challenges influence dietary choices?

How do animal-sourced foods correlate with mental health?
Can these association be explained by nutrient deficiencies?
Can vegetarianism be a smokescreen for mental disorders?

List of key resources

How do animal-sourced foods correlate with mental health?

Even after adjusting for lifestyle and socioeconomic factors, vegetarians are more likely to experience depressive episodes. The more rigorous the study, the more consistent the association becomes. Additionally, vegetarian women frequently report higher rates of mental health challenges and menstrual issues, despite healthier physical profiles.

Omnivorous diets, by contrast, are linked to better mental health, and studies suggest that animal-based ketogenic diets may even help alleviate depression and anxiety. The consumption of meat is of particular interest but other animal-derived foods, such as eggs and fish, have also been linked to a lower likelihood of cognitive decline and dementia.

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Vegetarianism and mental health

Many studies have reported a link between vegetarianism and reduced mental health, which cannot readily be explained by conventional notions about healthy diets and lifestyles. For instance, in a cohort of 14,000+ Brazilians aged 35-75 years, a two-fold higher prevalence of depressive episodes was found for vegetarians, after correction of socioeconomic, lifestyle factors, and nutrient deficiencies [Kohl et al. 2023]. Similarly, and although the level of physical activity and body mass indices of (semi-)vegetarian women suggest a health bonus compared to non-vegetarians, an Australian study showed that the former may more often report menstrual problems and poor mental health [Baines et al. 2007]. For vegetarians, consumers of plant-based meat alternatives had a higher risk of depression than non-consumers [Navratilova et al. 2024].

In contrast, diets of the omnivore type are associated with reduced psychological disorders [Salehi-Abargouei et al. 2019]. Moreover, case reports suggest that the adoption of animal-based ketogenic diets can lead to complete remission of major depression and generalized anxiety disorder within 7-12 weeks [Calabrese et al. 2024], but more studies are needed.

The role of meat intake

A low intake or avoidance of meat in particular is inversely associated with mental health and depression [O’Connor et al. 1987; Neumark-Sztainer et al. 1997; Perry et al. 2001; Lindeman et al. 2002; Klopp et al. 2003; Bas et al. 2005; Bardone-Cone et al. 2012; Michalak et al. 2012; Burkert et al. 2014; Herranz Valera et al. 2014; Zuromski et al. 2015; Asanova 2017; Zhang et al. 2017; Kapoor et al. 2017 Barthels et al. 2018; Forestell & Nezlek 2018; Hibbeln et al. 2018; Matta et al. 2018; Nezlek et al. 2018; Li et al. 2019; Dobersek et al. 2020, 2021; Iguacel et al. 2020; Parra-Fernández et al. 2020; Paslakis et al. 2020; Sergentanis et al. 2020; Ocklenburg & Borawski 2021]. One systematic review suggested, however, that the evidence is contradictory, possibly due to the heterogeneity of the studies analysed [Jain et al. 2022]. Yet, the more rigorous the study, the more positive and consistent the association between meat consumption and better mental health [Dobersek et al. 2023]. However, the causal direction of these associations is not clear (if causality is to be assumed in the first place, which remains uncertain given the limitations of observational research) [Dobersek et al. 2023].

Moreover, low meat consumption by women during the prenatal period is associated with increased risk of substance abuse of their offspring in adolescence, possibly involving vitamin B12 malnutrition [Hibbeln et al. 2017]. In older adults, low meat consumption parallels an increased incidence of dementia and Alzheimer's disease [Ngabirano et al. 2019].

The role of animal-sourced foods other than meat

In older adults, the eating of more than one egg a week is associated with a 50-% lower risk of Alzheimer's [Pan et al. 2024]. Fish consumption is also associated with a lower likelihood of cognitive impairment and decline and, potentially, of dementia and Alzheimer’s disease [Godos et al. 2024].

Can these association be explained by nutrient deficiencies?

It is likely: meat, fish, eggs, and liver are rich sources of iron, zinc, vitamin B12, DHA, and choline, which are vital for brain health, neurodevelopment, and cognitive function. Considering that meat has played a crucial role in the evolution of large human brains, it is understandable that deficiencies in its key nutrients are linked to conditions such as low IQ, depression, and dementia. A Kenyan intervention trial provided direct evidence of this connection, showing that supplementing the diets of undernourished children with meat led to notable improvements in their school performance.

To explain these relationships between animal-sourced foods and neural health, several potential mechanisms are known. For instance, vegetarians and vegans face higher risks of vitamin B12 and long-chain omega-3 deficiencies, which then cause depression, anxiety, and cognitive decline. For these reasons, psychiatrists recommend screening for such deficiencies in mentally ill patients, particularly those adhering to plant-based diets. During pregnancy, insufficient intake of animal-sourced foods can result in vitamin B12 deficiencies in offspring, increasing the likelihood of neurodevelopmental disorders. Early-life malnutrition exacerbates these risks, potentially impairing neurodevelopment with lasting consequences for mental health.

Creatine, abundant in meat, enhances short-term memory, while carnitine has neuroprotective properties. Zinc, crucial for neurotransmission and memory, can lead to depression-like symptoms when deficient. Iron is often lacking in vegetarian diets, causing fatigue, poor concentration, and mood disturbances. Choline, vital for producing the neurotransmitter acetylcholine, supports memory and brain development, particularly in early life. Long-chain omega-3 fatty acids such as EPA and DHA are essential for brain structure, neuroplasticity, and mood regulation, reducing age-related cognitive decline and mood disorders. Finally, lutein, found in egg yolks, is involved in the development and maturation of the brain in early life and facilitates cognitive performance, especially in older adults.

It needs to be stressed, however, that certain plants also offer brain-protective compounds such as magnesium, vitamins C and E, carotenoids, and polyphenols. Despite the fact that studies often focus on vegetarianism, the dietary root cause of the rise in mental disorders may as well be the increasing share of nutrient-poor ultra-processed foods in the diet.

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Poor mental health could be a matter of poor diet, especially as the result of nutrient deficiencies. For instance, closer adherence to meat restriction based on EAT-Lancet recommendations was associated with poorer mood, while leading to a risk of being deficient in certain nutrients [Young 2022].

Protective compounds

Although some of the protective components for brain health are more readily sourced from plant materials, including magnesium and vitamins C and E, as well as carotenoids and polyphenols, other are more bioavailable in animal-sourced foods [Gómez-Pinilla 2010; Puri et al. 2023]. Depression is sometimes also associated with low cholesterol levels [Fiedorowicz & Haynes 2014], but results are not always consistent [Zhang et al. 2022]. Components that affect brain health and are present in animal-source foods include:

Vitamin B12. Maintains the myelin sheaths that protect the nerves. It is one of the most critical nutrients involved in the neural development of infants and children, in particular when vegan diets are followed; see elsewhere on this website for a detailed analysis. Psychiatrists have advised investigating for vitamin B12 deficiency in psychiatrically ill patients, including acute psychosis, especially if they are vegetarian [Jayaram et al. 2013; Sahoo et al. 2024].

Vitamin B6. Together with vitamin B12 and vitamin B9 (leafy vegetables and liver are good sources), vitamin B6 is able to lower homocysteine, and as such involved in slowing the rate of accelerated brain atrophy in mild cognitive impairment in older adults who convert to Alzheimer's disease [Smith et al. 2010]. Supplementation with vitamins B6, B9, or B12 also has positive effects on memory performance in women of various age [Bryan et al. 2002].

Vitamin D. Regulates neurogenesis, inflammation, and calcium signaling; also stimulates the transcription of serotonin which can affect mood [Huiberts & Smolders 2021]. Low vitamin D levels are linked to cognitive impairments and neurodegenerative diseases, especially cognitive decline in older adults [Llewellyn et al. 2014].

Iron. Crucial for the growth and branching of neurons, myelination, and oxygen supply while in the womb [Gupta 2016]. Deficiency during infancy will negatively affect the developing brain, which may lead to long-term behavioral and developmental outcomes during later childhood, including school achievements [Lozoff et al. 2006]. Iron overload in the brain, on the other hand, will lead to a decline in motor and cognitive functions [Puri et al. 2023].

Zinc. Found in high concentrations in the hippocampus, a region involved in neurotransmission, learning, and memory [Gupta 2016]. Deficiency causes abnormal glucocorticoid secretion and synaptic activity, which can increase depression-like behavior [Takeda 2011].

Choline. A precursor for acetylcholine, a neurotransmitter essential for memory and attention. Moreover, increased choline supply during the first 1000 days of life facilitates normal brain development [Derbyshire & Obeid 2020].

EPA and DHA. These long-chain omega-3 fatty acids are integral to the structure of brain cell membranes and neuroplasticity, while also regulating inflammation levels. Moreover, DHA contributes to synaptic function and is vital for learning, memory, and brain health during age-related cognitive decline [Yurko-Mauro et al. 2010]. Besides ameliorating cognitive decline, long-chain omega-3 fatty acids also form the basis for treatment in patients with mood disorders [Gómez-Pinilla 2010].

Lutein and other carotenoids. Accumulate in the retina and brain, and are linked to improved cognitive performance [Demmig-Adams et al. 2020]. Although carotenoids are primarily sourced from plants, they can also be present in animal foods, as is the case for lutein in egg yolk. Lutein is preferentially accumulated in the eye and brain in early life and throughout the life span, and is involved in their development and maturation [Gazzolo et al. 2021]. In older adults, lutein was shown to be positively associated with brain structure and neural efficiency during cognitive tasks [Yagi et al. 2021].

Creatine. Improves short-term memory and intelligence/reasoning, even of healthy individuals [Avgerinos 2018]. The molecule is involved in cognitive processing, brain function, and recovery from trauma [Dolan et al. 2019, Roschel et al. 2021; Forbes et al. 2022].

Carnitine. A neuroprotective agent [Ueno et al. 2021; Morid et al. 2023]. Carnitine supplementation has demonstrated favorable therapeutic effects in the management of hepatic encephalopathy, Alzheimer's disease, carpal tunnel syndrome, migraine, and cognitive disorder, but not depression [Wang et al. 2024]. Its plasma levels show an inverse association with cognitive impairment after ischemic stroke [Che et al. 2022].

Protective foods

Simply supplementing these molecules often leads to inconsistent results, so that it may be more important to look at dietary strategies [Puri et al. 2023]. Although studies on the role of animal-sourced foods on cognitive functions are limited, benefits are compelling [Balehegn et al. 2019]:

Meat. Meat has played a key role in the evolutionary transition to large brains in humans [see elsewhere on this website]. It should not be surprising therefore that deficiencies in the micronutrients found in meat have been linked with brain-related disorders (i.e. low IQ, autism, depression, and dementia) [Gupta 2016]. These nutrients include iron, zinc, vitamin B12, and DHA, among others. Meat is also rich in creatine and carnitine. Administrating these nutrients through an intervention trial with meat in Kenyan school children has shown an improvement in cognitive and behavioral outcomes, including in maths and language subjects [Neumann et al. 2007].

Liver. Rich in many important nutrients, including choline, iron, and vitamins B6, B9, and B12.

Fish. Fatty fish contains the long-chain omega-3 fatty acids EPA and DHA, and is one of the only good dietary sources of vitamin D.

Eggs. The consumption of eggs offers benefits for neurodevelopment and brain health, as they provide choline, long-chain omega-3 fatty acids, and lutein [Wallace 2018; Christifano et al. 2023; Pan et al. 2024].

Ultra-processed diets

The root cause of the surge in mental disorders is likely not vegetarianism, but rather the increasing share of ultra-processed foods in our diets, as these are usually nutrient-poor and lead to metabolic disturbance. Ultra-processed foods have been associated with poor mental health, but more research is needed to unravel mechanisms and prove causality [Gómez-Donoso et al. 2020; Lane et al. 2022, 2023, 2024; Contreras-Rodriguez et al. 2023; Narges Masloomi et al. 2023].

Can vegetarianism be a smokescreen for mental disorders?

Vegetarianism is sometimes used to conceal underlying mental health issues, trauma, and eating disorders, particularly among adolescents and young adults. Eating disorders affect at least 10% of this population in Europe, with vegetarianism being notably prevalent among female individuals with anorexia nervosa. Research suggests that the majority of anorexia patients adhere to vegetarian diets, often as a socially acceptable way to justify restrictive eating patterns or maintain control over food intake.

Interestingly, semi-vegetarians with orthorexic tendencies—marked by an obsessive fixation on ‘healthy’ eating—frequently display higher levels of depressive symptoms compared to both vegetarians and omnivores. Especially when vegetarianism is driven by psychological distress rather than ethical or health motivations, its restrictive nature can worsen mental health. This issue is further compounded by nutrient deficiencies common in vegetarian diets, such as insufficient intake of vitamin B12, iron, and omega-3 fatty acids, all of which are critical for mental and cognitive health.

Mental health professionals are encouraged to evaluate dietary habits in patients with eating disorders, especially those who follow (semi-)vegetarian diets. While well-formulated vegetarianism can be an adequate dietary choice, its potential use as a cover for disordered eating underscores the importance of thorough assessment and individualized care.

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Vegan and vegetarian diets could be used as a smokescreen for mental disorders and eating pathologies [Lindeman et al. 2000; Zickgraf et al. 2020; Albertelli et al. 2024]. Moreover, research has shown that people who had greater experiences of trauma, especially intimate partner violence, are more likely to choose a plant-based diet, which highlights the need to take trauma exposure into account when examining why some plant-based eaters have higher levels of mental disorders [Nomamiukor et al. 2024].

Eating disorders are affecting at least 10% of the European adolescents and young adults [Smink et al. 2012; Keski-Rahkonen & Mustelin, 2016]. In adolescents, vegetarianism is a fast-growing phenomenon observed in a majority of patients with anorexia nervosa [Albertelli et al. 2024]. Between 50-85% of the anorexic nervosa patients are known to adhere to vegetarian diets [Bardone-Cone et al. 2012; Albertelli et al. 2023]. Vegan and vegetarian diets are also commonly associated with orthorexic eating behaviours [Barthels et al. 2018; Brytek-Matera 2021]. For instance, in a survey of Polish teens, 60% of the vegetarians were at risk of orthorexia nervosa [Kozik & Całyniuk 2024]. In any case, the complex nature of the diet-depression requires further investigation, as semi-vegetarians with strong orthorexic tendencies tend to show more depressive symptoms than omnivores and vegetarians [Hessler-Kaufmann et al. 2020]. In another study, meat-reducers had higher depression scores than either meat-eaters or vegetarian/vegans, which could be linked to cognitive dissonance [Hopwood 2022].

Individuals that are prone to mental disorders and problematic eating behaviour may have to pay attention to the levels of animal-sourced foods in their diets.

List of key resources

Albertelli et al. (2024) Vegetarianism and eating disorders: The subjective experience of healthcare professionals. Appetite.
Dobersek et al. (2023) Meat and mental health: A meta-analysis of meat consumption, depression, and anxiety. Critical Reviews in Food Science and Nutrition.
Wallace (2018) A comprehensive review of eggs, choline, and lutein on cognition across the life-span. Journal of the American College of Nutrition.
Young (2022) Adherence to the EAT–Lancet diet: unintended consequences for the brain? Nutrients

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