I’ve made the analogy before of a neglected car to a poorly-maintained human body. Neither will function at their optimum if they do not receive the care they need. You need to give your car engine oil and coolant for it to run well. Likewise, you need to provide your body with the micronutrients and macronutrients it needs to be healthy. There are certain nutrients your brain requires in specific levels in order to manufacture neurotransmitters and complete other processes. If it does not get these, it may quite literally malfunction or glitch. A symptom of the brain glitching could present as depression. It may be strange to think of people in the West experiencing malnutrition, but it does happen. Let’s take a look at the nutrient deficiencies that can make you depressed.

Thiamine

Thiamine is used in the process of extracting energy from blood sugar (1). A lack of thiamine will throw a wrench into this process, and as the brain experiences a drop in energy, you may start seeing signs of depression, including lethargy, poor memory, and a lack of appetite. Aside from depression, a lack of thiamine can also result in irritability, insomnia, and anxiety (1).

Causes of low thiamine

• Alcohol abuse – one of the top causes of thiamine deficiency
• Diet high in white flour, white rice, and white sugar – another leading cause of thiamine deficiency
• Caffeine – if you have more than 2 cups of coffee a day, you could be at risk
• Needing a higher intake of thiamine than usual – such as when doing heavy exercise, experiencing a fever, or while pregnant or breast-feeding; also if hyperthyroid
• Liver disorder
• Absorption problems – including gastric bypass surgery, ongoing diarrhea; the body does not store thiamine, so stores can be depleted quickly
• Certain drugs – like antacids and metformin
• Magnesium deficiency – thiamine and magnesium work together to make energy from blood sugar
• Dialysis
• Eating too many foods high in thiaminase – this is an enzyme that breaks down thiamine. It is found in sprouts and some types of raw seafood; see here for a good list on seafood

(Data taken from 2 – 4 on reference list.)

Excellent sources of thiamine

(Daily value calculations are for a 2000 calorie diet.)

1. Nutritional yeast (non-fortified): 2 heaping tablespoons has 2.08 mg, which is 170% DV
2. Pork tenderloin: 6 oz of broiled pork tenderloin has 1.6 mg, 137% DV
3. Ham: 1 cup of cured ham has 1.1 mg, 96% DV
4. Sunflower seeds: 2 oz of hulled sunflower seeds has .83 mg, 69% DV
5. Tahini: ¼ cup of tahini has .73 mg, 61% DV

Vitamin B12

Your system uses vitamin B12 to make dopamine and serotonin, neurotransmitters associated with good mood (5). So, without sufficient B12, how can it keep up production of these neurotransmitters? Like thiamine, B12 is also involved in the metabolic process, meaning that a deficiency may cause fatigue (5). Interestingly, B12 is used to create the myelin sheath that coat nerves and insulates them (5). Myelin is involved in memory function, so it should be no surprise that insufficient B12 can result in poor memory. Anxiety and irritability are other mental health symptoms that can arise from lack of B12 (6).

Causes of low B12

• Weak stomach acid – the top cause of low B12 is poor absorption caused by weak stomach acid
• Intestinal damage – from gastric bypass surgery, celiac disease, inflammatory bowel disease, etc.
• Certain drugs – such as proton pump inhibitors and antacids
• Being vegan without supplementing B12
• Bad bacteria/parasites – these compete with their host for B12
• Liver disease
• Deficiency in the enzyme pepsin – necessary for absorption of B12
• Ongoing gastritis – the stomach makes a protein called intrinsic factor, needed for B12 absorption

(Data taken from 7 – 9 on reference list.)

Excellent sources of B12

1. Clams: 3 oz of cooked clams has 84.1 mcg – 3,502% DV!
2. Liver: one 81g slice of beef liver has 67.3 mcg, 2,806% DV
3. Oysters: 6 oz of canned Eastern oysters has 32.5 mcg, 1,355% DV
4. Mackerel: a 6oz fillet of Atlantic mackerel has 32.3 mcg, 1,346% DV
5. Octopus: 3 oz of cooked octopus has 30.6 mcg, 1,275% DV

Folate

Folate is used to make neurotransmitters – specifically, dopamine, norepinephrine, and serotonin (10). According to one study, folate decreases side effect issues of at least one psychiatric medication (fluoxetine) and apparently boosts its antidepressant effect (10). However, I’m left wondering: did folate actually “boost” fluoxetine’s effect or was folate by itself entirely responsible for the positive response? It’s hard to say because there was no control group that received only folate and no fluoxetine. However, two other studies compared a folate only-group with a group taking one of two other antidepressant medications. One of these studies that compared a folate group with an amitriptyline group showed close results between the two, and another that compared a folate-only group to a trazadone group concluded with the folate group doing better (10)!

Causes of low folate

• MTHFR gene mutation – may possibly affect production of a necessary enzyme to convert folic acid into a usable form; research is not entirely conclusive
• Chronic alcohol use
• Some drugs – such as metformin, phenobarbital, and anti-seizure drugs
• Needing a higher intake of folate than usual – such as when pregnant or breastfeeding
• Poor diet
• Malabsorption – such as due to celiac disease or enzyme deficiency
• Dialysis – removes folate

(Data taken from 11 – 12on reference list.)

Excellent sources of folate

1. Edamame: 1 cup frozen has 482.1 mcg, 121% DV
2. Cranberry beans: 1 cup cooked has 366.4 mcg, 92% DV
3. Lentils: 1 cup cooked has 358.4 mcg, 90% DV
4. Black eyed peas: 1 cup boiled has 355.7 mcg, 89% DV
5. Lamb liver: 3 oz has 340 mcg, 85% DV

Vitamin D

Research has shown that the lower level of vitamin D a person has, the higher the likelihood of depression (13). Notably, vitamin D plays a role in the production of serotonin, dopamine, and other neurotransmitters and helps maintain the levels thereof (13). Moreover, vitamin D helps the immune system work more effectively and has an anti-inflammatory effect, which could be protective for the brain (13, 14). Unfortunately, low vitamin D appears to be among the most common nutrient deficiencies in America (15).

Causes of low Vitamin D

• Lack of skin exposure to sun – the Merck Manual recommends 15 minutes of sun exposure 3 times per week, though it is unclear if this is sufficient for darker skin tones
• Habitual use of sunscreen – sunlight must touch areas of unprotected skin for vitamin D synthesis
• Conversion problems – such as from ongoing liver or kidney disease
• Deficiency in zinc, calcium, and magnesium – vitamin D can’t work without these
• Deficient diet
• Some drugs – orlistat, laxatives, phenobarbital, cholestyramine, etc.
• Obesity
• Weight loss surgery – like gastric bypass surgery
• Medical problems – such as celiac disease, cystic fibrosis, and Crohn’s disease

(Data taken from 14, 16-17 on reference list.)

Excellent sources of Vitamin D

1. Cod liver oil: 1 tbsp has 33.8 mcg, 169% DV
2. Sockeye salmon: 6 oz fillet has 28.4 mcg, 142% DV
3. Raw Cremini mushrooms placed under UV light or sunlight: 1 cup has 27.8 mcg, 139% DV
4. Raw Portobellos placed under UV light or sunlight: 1 cup chopped has 24.4 mcg, 122% DV
5. Raw white button mushrooms placed under UV light or sunlight: 1 cup has 18.3 mcg, 92% DV

Zinc

The human brain needs zinc to form new brain cells, which, despite the previous view in the medical field, it continues to do even in adulthood (19). As with vitamin D, research ties lower levels of zinc to increased depression (19). Anxiety, irritability, and brain fog are other mental health symptoms associated with low zinc (18, 19, 21).

Causes of low zinc

• Needing a higher intake – due to pregnancy or breastfeeding
• Low protein diet
• Malabsorption
• Diet high in phytates – legumes, whole grains, and nuts tend to be high in phytates
• Medical disorders – such as diabetes, ongoing kidney disease, liver or pancreas problems, sickle cell disease
• Alcohol use
• Coffee
• Medications – such as diuretics, steroids, antacids, hormones

(Data taken from 18 – 19 on reference list.)

Excellent sources of zinc

1. Eastern oysters: 3 oz of canned oysters has 77.3 mg, 703% DV
2. Beef chuck: 6 oz steak has 18.6 mg, 169% DV
3. Lamb shoulder, roasted: 6 oz has 12.4 mg, 113% DV
4. Alaskan king crab: 1 leg has 10.2 mg, 93% DV
5. Oats: 1 cup uncooked has 6.2 mg, 56% DV

Iron

Iron is most well known as a component of red blood cells, which supply nutrition and oxygen around the body. Throughout the world, iron deficiency is the most common nutrient deficiency (23). Like most of the other nutrients on this list, iron is also used in the process of making the neurotransmitters serotonin and dopamine (23). Low iron levels is also associated with anxiety (23).

Causes of low iron

• Insufficient diet – vegans in particular need to be mindful to eat more iron-rich foods
• Blood loss – such as from menstruation
• Malabsorption – can be caused by celiac disease
• Needing a higher intake – due to pregnancy or extreme exercise
• Dialysis

(Data taken from 22 on reference list.)

Excellent sources of iron

1. Lamb liver: 6 oz has 17.3 mg, 96% DV
2. Tofu made with calcium sulfate: 1 cup has 13.3 mg, 74% DV
3. Beef skirt steak: 6 oz grilled has 9.3 mg, 52% DV
4. Eastern Oysters, canned: 3 oz 5.7 mg, 32% DV
5. Edamame: 1 cup boiled has 8.8 mg, 49% DV

Why a Person May Become Malnourished

A fairly recent study on the connection between diet and depression concluded, “The findings suggest that the healthy dietary pattern was significantly associated with a reduced odds of depression… whereas the unhealthy dietary pattern increased it…” (24).

So what may cause unhealthy dietary patterns in countries and regions where good food is available?

High costs. Good quality food tends to be more expensive than poor quality food.

Not realizing you’re not eating a good diet. Not being educated in nutrition and not being health conscious. It’s also true that many people are used to eating food depleted of nutritional value, focusing on taste over health. Perhaps you have been raised eating a certain way, and everybody else seems to be doing just fine. However, they are probably not doing as well as others may think because of the prevalence of health problems.

With a car, one can consult the owner’s manual to find out what it needs, when, and in what amounts. With the human body, one can carefully analyze symptoms to discover possible deficiencies or simply take blood tests.

Looks above all else. Excess focus on the external, specifically, fixating on weight only. Deficiencies from eating disorders and excess dieting.

Existing depression complicated by a poor diet. A lot of people with depression tend to neglect their bodies. This may even be a symptom of the condition. I think that for a number of people with depression, the depression itself may be triggered by another factor (such as a bad life event) and that the following self-neglect may lead them to adapt a problematic eating pattern, which then results in nutritional deficiencies. The problem is then exacerbated and prolonged.

Bottom line, if you have depression, it’s probably a good idea to check your diet to make sure your brain is getting all the nutrients it needs to function properly.

References:

1. What to Know About Vitamins and Mental Health. (2023). WebMD. https://www.webmd.com/vitamins-and-supplements/what-to-know-about-vitamins-and-mental-health

2. Johnson, L.E. (2022). Thiamin Deficiency. Merck Manual. https://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/thiamin-deficiency

3. Arthur, M. (2019). 12 signs you might have a thiamine deficiency. Baylor Scott & White Health. https://www.bswhealth.com/blog/12-signs-you-might-have-a-thiamine-deficiency#:~:text=Although%20thiamine%20deficiency%20is%20rare,Dialysis%20for%20chronic%20kidney%20disease

4. Dobberstein, L.J. (2015). Magnesium and Vitamin B1 – Team Players Needed for Brain, Muscles, Metabolism, and More. Wellness Resources. https://www.wellnessresources.com/news/magnesium-and-vitamin-b1-team-players-needed-for-brain-muscles-metabolism#:~:text=Magnesium%20is%20required%20for%20thiamin,hundreds%20of%20essential%20life%20functions.

5. The Benefits of Vitamin B12. (2020, July 27). Texas Neuro Spine. https://www.texasneurospine.com/blog/the-benefits-of-vitamin-b12/?bp=35453#:~:text=B12%20is%20a%20key%20nutrient,focus%20and%20memory%20as%20well.

6. Pedersen, T. (2023). Understanding the Relationship Between B12 Deficiency and Depression. PsychCentral. https://psychcentral.com/depression/b12-and-depression

7. Johnson, L.E. (2022). Vitamin B12 Deficiency. Merck Manual. https://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/vitamin-b12-deficiency?query=b12%20deficiency

8. Medications Known to Decrease Vitamin B12 Levels. (2015). Evidence-Based Medicine Consult. https://www.ebmconsult.com/articles/vitamin-b12-medication-interactions-lower-levels#:~:text=Summary%3A,proton pump inhibitors (PPI).

9. Vitamin B12 Deficiency. (n.d.). John Hopkins Medicine. https://www.hopkinsmedicine.org/health/conditions-and-diseases/vitamin-b12-deficiency-anemia

10. Fava, M. & Mischoulon, D. (2009). Folate in Depression: Efficacy, Safety, Differences in Formulations, and Clinical Issues. Psychiatrist.com. https://www.psychiatrist.com/jcp/folate-depression-efficacy-safety-differences-formulations/#:~:text=Supplementation%20with%20folate%20may%20help,norepinephrine%2C%20serotonin%2C%20and%20dopamine.

11. Johnson, L.E. (2022). Folate Deficiency. Merck Manual. https://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/folate-deficiency

12. Ruscio, M. (2021). What’s Really Causing Your ‘MTHFR Gene Mutation’ Symptoms. Dr. Ruscio DC. https://drruscio.com/mthfr-gene-mutation-symptoms/#:~:text=Symptoms%20Attributed%20To%20MTHFR%20Mutations,treat%20daily%20in%20our%20clinic.

13. Menon, V, Kar, S.K., Suthar, N., & Nebhinani, N. (2020). Vitamin D and Depression: A Critical Appraisal of the Evidence and Future Directions. NCBI. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6970300/

14. Vitamin D: Separating Fact from Fiction. (2016). Brain&Life. https://www.brainandlife.org/articles/long-known-for-promoting-bone-health-vitamin-d-has-also#:~:text=%22Vitamin%20D%20also%20may%20protect,Johns%20Hopkins%20Medicine%20in%20Baltimore.

15. Drake, V.J. (2017). Micronutrient Inadequacies in the US Population: an Overview. Oregon State University. https://lpi.oregonstate.edu/mic/micronutrient-inadequacies/overview#:~:text=Specifically%2C%2094.3%25%20of%20the%20US,and%2038.9%25%20for%20vitamin%20C.

16. Johnson, L.E. (2022). Vitamin D Deficiency. Merck Manual. https://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/vitamin-d-deficiency-and-dependency

17. Vitamin D Deficiency. (2022?). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/15050-vitamin-d-vitamin-d-deficiency

18. Johnson, L.E. (2023?). Zinc Deficiency. Merck Manual. https://www.merckmanuals.com/home/disorders-of-nutrition/minerals/zinc-deficiency?query=Zinc%20Deficiency

19. Gower-Winter, S.D. & Levenson, C.W. (2012). Zinc in the central nervous system: from molecules to behavior. NCBI. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3757551/

20. Petrilli, M.A., Kranz, T.M., Kleinhaus, K., Joe, P., Getz M., et al. (2017). The Emerging Role for Zinc in Depression and Psychosis. NCBI. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5492454/

21. 10 Signs and Symptoms of Zinc Deficiency. (n.d.). Center for Family Medicine. https://centerforfamilymedicine.com/nutritional-information/10-signs-and-symptoms-of-zinc-deficiency/

22. Johnson, L.E. (2023?). Iron Deficiency. Merck Manual. https://www.merckmanuals.com/home/disorders-of-nutrition/minerals/iron-deficiency

23. Kim, J. & Wessling-Resnick, M. (2014). Iron and Mechanisms of Emotional Behavior. NCBI. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4253901/

24. Khosravi, M., Sotoudeh, G., Amini, M., Raisi, F., et al. (2020). The relationship between dietary patterns and depression mediated by serum levels of Folate and vitamin B12. NCBI. https://pubmed.ncbi.nlm.nih.gov/32054533/#:~:text=The%20mediation%20analysis%20showed%20that,and%20vitamin%20B12%2C%20based%20on

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