Diet and Mental Health

Eat healthy to be happy, be happy to feel healthy

There is actually scientific evidence behind why a big bowl of tomato pasta (esp with greens!) can make you happy af. By the end of this, you’ll understand why.

This is a summary of the chapter “How Not to Die from Suicidal Depression” in the book “How Not to Die” by Dr. Greger, Physician and M.D. I include facts that I found most interesting and relevant. I always knew diet had a profound effect on the body, but it is truly remarkable the extent to which your diet can affect your happiness. And also, how your happiness can affect your health!

The chapter begins with a testimony by a women named Margaret. She was diagnosed with clinical depression at the age of 10, and since then heavily medicated her entire life. She eventually got married, but divorced some time after and was hospitalized numerous times. After hearing Dr. Greger speak in her church, she decided to stop taking her medication (under her doctors supervision) and adopt a whole plant based diet. Nine years passed on this diet, and she has never relapsed, been hospitalized, or had suicidal thoughts. “I owe you my life!” was her final words to Dr. Greger.1

In 1946, the World Health Organization defined health as “a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity”2, meaning mental health can be equally as significant as physical health.

Recently, “positive psychology” studies have emerged to show the relationship between positive mental and physical health. Prospective studies (follow individuals change over time) revealed that those who began happier ended up healthier later on in life. A collection of seventy prospective studies also showed that happier individuals tend to live longer.3

So is being happy an effect of good health, or does being happy lead to better health?

This idea was put to the test at Carnegie Mellon University. Hundreds of both happy and unhappy participants were paid to have the common cold virus dripped into their noses. If one’s immune system is strong enough to fight the virus off, exposure to it does not necessarily make one sick. The results revealed that roughly one third of the negative emotion individuals became sick, while one fifth of the happy individuals developed the cold.4

Researchers accounted for confounding factors (factors that could yield inaccurate data) including sleep schedules, exercise routines, and stress levels. In a proceeding study, paid participants were exposed to the influenza virus. Again, happier individuals became less sick compared to negative-emotion individuals. Remarkably, this shows that possessing a positive mentality can improve your health. Diet also plays a significant role in mental health.
Foods to avoid for mental and physical health: Animal products

Arachidonic acid is pro-inflammatory compound which likely impairs one’s mood by “adversely impacting mental health via a cascade of neuroinflammation”5. Eggs and chicken in particular have very high arachidonic acid content. Beef, pork, and fish are relatively high in this malignant compound as well. Painkillers like aspirin and ibuprofen actually work by preventing the metabolism of arachidonic acid, which naturally creates many inflammatory products.

In a randomized control study, omnivores who ate meat daily had eggs, chicken, and other meat products eliminated from their diet. After just two weeks, the subjects experienced elevated mood levels. It was concluded that less meat consumption may help protect mood in omnivores, especially those who are susceptible to mental disorders, i.e. depression.  

Foods to eat for a happy body and mind: 

To put it simply, Plant Foods!

The “Monoamine Theory” suggests that depression is caused by a chemical imbalance in the brain. Nerves use neurotransmitters, or chemical messengers, to communicate with each other. Monoamines is an important neurotransmitter (includes dopamine and serotonin) that is broken down by monoamine oxidase (MAO), an enzyme (proteins that increase reaction rates). This aligns with the fact that depressed people have more MAO in their brain compared to happier individuals.

Berries, apples, onions, grapes, green tea, contain many phytonutrients that block MAO. Spices including cloves, oregano, cinnamon, nutmeg also induce this effect. Results of studies have shown that daily consumption of fruits and vegetables leads to a happier, calmer, more energetic life. Eating 7 servings of fruit or 8 servings of vegetables per day is recommended for true effectiveness.6 
How Carbs make you happier: the science

Many are familiar with serotonin, the “happy hormone”. Despite some plant foods containing high amounts of serotonin, dietary serotonin cannot enter into our brains due to a “blood-brain barrier”1 , meaning it cannot travel from our blood to our brain. However, Tryptophan, an amino acid and building block of serotonin can be ingested, enter our blood, and enter our brains.

So does that mean we should consume protein-rich food sources to get more tryptophan? knowing amino acids are the building blocks of proteins.

In the 1980s, this idea was tested. A tryptophan supplement was distributed, and received fatal results. The failure was likely due to “amino acids in protein rich foods crowding out the tryptophan for access to the brain”.

BUT, carbohydrates do the opposite!

Carbohydrates allow tryptophan to gain greater access to the brain by facilitating non-tryptophan amino acids out of the bloodstream, and into the muscles. Thus, ideal food sources including sesame, sunflower, and pumpkin seeds have a high tryptophan to protein ratio. Even a high carb meal such as waffles and orange juice contributed to higher tryptophan levels than a meal rich in protein including eggs, turkey, and cheese.7

In a placebo controlled, double-blind study, social anxiety disorder was treated with butternut squash seeds. Within only an hour of consumption, anxiety levels showed an objective and measurable improvement.8 The powerful effect of diet is more immediate than we may realize.

AMAZE AF - Antioxidants and Folate

Data suggests that free radicals (highly reactive molecules) damages our tissues, DNA, and accelerates aging to name a few harmful effects. More recently, it’s been shown that it also induces acceleration of mental disorders including depression; specially, some nerve cells in the brain responsible for certain emotions die from free radical damage.9

Fruits and vegetables are high in antioxidants, which prevent free radical damage, and thus are an effective protective measure against depression.

A nationwide American study determined the level of carotenoid phytonutrient within people’s blood. Foods rich in carotenoid include many orange, yellow, and red antioxidant pigmented foods like sweet potatoes and dark green leafy vegetables. Those with greater carotenoid content in their blood experienced less depression risk; there was also a dose-response relationship, meaning the higher the phytonutrient blood concentration, the better people felt.11 Lycopene, a red carotenoid found in tomatoes has the greatest antioxidant activity.

Folate is a B vitamin found mainly in greens and beans. Recent prospective studies show that the risk of depression may be increased three times by low dietary folate levels.12 Dark leafy greens, citrus fruits, and legumes all have high folate content. 

So why not just take a dietary supplement?

Studies show that only dietary antioxidants have protective effects against depression. This suggests that the “form and delivery of antioxidants we consume are crucial to ensure their best effects”1 .

I’ve long advocated “eating the rainbow to feel like one”, but after reading this chapter I feel much more confident in this statement. There are so many reasons to eat plant based (ethical, health, environment); I hope that this information pushes you to make a change today. Your choice is your power. Choose plant-based and become the best version of yourself, from the inside out!



  1. Greger, Michael . How Not To Die . 1st ed., Flatiron Books , 2015.

  2. Preamble to the Constitution of the World Health Organization as adopted by the International Health Conference, New York, 19-22 June 1946; signed on 22 July 1946 by the representatives of 61 states (Official Records of the World Health Organization, no. 2, p. 100) and entered into force on 7 April 1948.

  3. Chida Y, Steptoe A. Positive psychological well-being and mortality: a quantitative review of prospective observational studies. Psychosom Med. 2008;70(7):741-56.

  4. Cohen S, Doyle WJ, Turner RB, Alper CM, Skoner DP. Emotional style and susceptibility to the common cold. Psychosom Med. 2003;65(4):652-7.

  5. Beezhold BL, Johnston CS, Daigle DR. Vegetarian diets are associated with healthy mood states: a cross-sectional study in Seventh Day Adventist adults. Nutr J. 2010;9:26.

  6. White BA, Horwath CC, Conner TS. Many apples a day keep the blues awa- daily experiences of negative and positive affect and food consumption in young adults. Br J Health Psychol. 2013;18(4):782-98.

  7. Wurtman RJ, Wurtman JJ, Regan MM, McDermott JM, Tsay RH, Breu JJ. Effects of normal meals rich in carbohydrates or proteins on plasma tryptophan and tyrosine ratios. Am J Clin Nutr. 2003;77(1):128-32.

  8. Schweiger U, Laessle R, Kittl S, Dickhaut B, Schweiger M, Pirke KM. Macronutrient intake, plasma large neutral amino acids and mood during weight-reducing diets. J Neural Transm. 1986;67(1-2):77-86.

  9. Michel TM, Pulschen D, Thome J. The role of oxidative stress in depressive disorders. Curr Pharm Des. 2012;18(36):5890-9.

  10. McMartin SE, Jacka FN, Colman I. The association between fruit and vegetable consumption and mental health disorders: evidence from five waves of a national survey of Canadians. Prev Med. 2013;56(3-4):225-30.

  11. Beydoun MA, Beydoun HA, Boueiz A, Shroff MR, Zonderman AB. Antioxidant status and its association with elevated depressive symptoms among US adults: National Health and Nutrition Examination Surveys 2005-6. Br J Nutr. 2013;109(9):1714-29.

  12. Tolmunen T, Hintikka J, Ruusunen A, et al. Dietary folate and the risk of depression in Finnish middle-aged men. A prospective follow-up study. Psychother Psychosom. 2004;73(6):344-9.


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